Moses Ludel

Well, Bill, you did everything possible to save fuel at these speeds, which of course would not be optimal for mileage. 1600-1800 rpm with a light load would post better mileage, partly due to available torque and less rpm, mostly to do with less wind effect. As you note, the headwind was not helpful at all. These trucks are far from aerodynamic under optimal conditions. Your mileage is very respectable. The SB intake elbow, as you share, will produce only subtle gains when the truck is not pushed or driven hard. The quicker EGT cooldown is commendable. This reduces load on the engine, cooling system and turbocharger. Heat is always a negative, and any opportunity to cool down the system is advantageous. I have no experience with the SB intake elbow. There are Banks and other devices that do show dynamometer gains. In my experience, most aftermarket upgrades for a Cummins turbodiesel engine intended for reasonable engine speeds and throttle settings will show only incremental gains. Cummins is not incompetent nor lacking in engineering prowess. They design and build engines for performance, fuel efficiency and reliability at "normal" diesel engine speeds. Stock components generally work well or certainly adequately for "normal" driving conditions. This applies to software tunes as well. When I did the Hypertech MaxEnergy Stage III tune upgrade, I had no illusions that my mileage would improve (despite Hypertech's claim that it would). Performance improved substantially but not fuel efficiency. This is not unusual for aftermarket performance upgrades. Do I have regrets? None at all. The tune unleashed latent engine potential. It also left me responsible for backing out of the throttle at times to protect the engine and 48RE transmission. Suffice to say, once an owner experiences the performance gain, they seldom elect to roll back the performance to stock tune. Moses

Hi, LaurieW...Do post the photos. I'm a big fan of I-H trucks and the Scout II/Traveler. 1979 is a good model year, one year before the end of production. The only advantage in the 1980 models is use of the Dana 300 transfer case (one year only). The Model 20 Spicer transfer case is fine in the '79, it just lacks the 300's lower gear ratio in low range. Also, the 300 has helically cut gears, arguably quieter running and more durable, but the Model 20's straight-cut gears do work well. This is certainly not a deal breaker or any reason to avoid the right 1976-1979 Traveler model. The scourge and rabbit hole with the Scout II/Traveler models is rust. When I consider any pre-owned vehicle, my three biggest concerns are 1) known history and documentation, 2) any indication of serious body/frame damage and 3) rust. Scouts are notorious for rust, especially at the Midwest, Northeast or any other corrosive environment with salted roads. Unfortunately, salted roads are now common in previously rust-free states like Nevada. When you post pictures, I will be watching for "originality" and lack of modifications plus any signs of rust or damage. History is very important if available. Full documentation and a continuous paper trail, which includes the Line Ticket on an I-H truck, would be desirable. Moses

Interesting, Jordan89oak, always good to see your posts...The wild card is whether it's easier to swap an LS V-8 into this chassis than a late 4.0L? I have dealt with the 4.2L/4.0L block mount issue, it's not a deal breaker. A light modification to the 4.2L block mount enables the fit-up. Let us know how this turns out. I'm still concerned about your passing emissions with this arrangement. The year of your CJ chassis would enable a straightforward TBI 305 or 350 V-8 swap (light duty 2WD truck emissions tier, same as your CJ) or an LS if desired. (LSX? Well that's not exactly Rubicon Trail material, it's more like sand drags ready.) I know you're a fan of the LS engines, and for good reason. You have experience with that engine family, and an emission legal LS swap is not difficult with aftermarket wiring and other peripherals available. The kicker for emissions is the cat/exhaust system, which California insists requires all cats that came with the engine donor's chassis. Here is insight into a 50-State legal LS engine conversion using a later light truck engine and 4L60E transmission. Steve Roberts and I went into detail on what it takes to be emission legal for California: https://4wdmechanix.com/moses-ludels-4wd-mechanix-magazine-hd-video-advance-adapters-jeep-tj-wrangler-ls-v-8-conversion/ Howell makes this wiring harness to ease the LS swap process: https://4wdmechanix.com/howell-introduces-lt1-lt4-wiring-harnesses/ Advance Adapters has the adapters for transmission-to-Dana 300, no big hurdles there. You can fab motor mounts from a universal GM V-8 motor mount kit. I did this article on diesel conversions and went into considerable detail on emission legality for California. The material applies to gasoline engine conversions as well: https://4wdmechanix.com/cummins-4bt-and-4-isb-diesel-engine-conversions/ See what you think when the 4.0L is running... Moses

Full Service...If I'm understanding your question, you have either a splined drive flange or manual locking hub removed from the wheel hub. You want to know how much play there should be between the stub axle shaft and the spindle with the flange or manual locking hub removed? CJ Jeep vehicles have either a bushing or a needle bearing and seal at the inner end of the spindle. The needle bearing or bushing supports the stub shaft at the inner end of the spindle. Either a bushing or a needle bearing (left in illustration below) provides support and centers the inner end of the stub axle. The outer splined drive flange or free-wheeling/manual locking hub provides the outer support for the stub axle. On a CJ front axle, the play that should be of concern is at this inner spindle bushing or needle bearing. You can reach into the open steering knuckle with a pry bar or large screw driver and lift the axle shaft U-joint up and down. You're looking for play between the bushing or needle bearing and the inner end of the stub axle shaft. Moving the stub axle sideways or "radially" at the open steering knuckle end will indicate whether you need to replace the spindle inner bushing or needle bearing and seal with a readily available and inexpensive rebuild "kit". (The image below is "Crown" parts.) You will likely need to reinstall the drive flange or manual locking hub to support the outer end of the stub axle shaft while you check for inner bushing or needle bearing wear. Otherwise, the outer end of the stub axle shaft will wobble and the shaft will move inward and outward. This would throw off your test results. There should be very little if any stub axle shaft movement sideways/radially. You're checking for a worn bushing or needle bearing or wear at the stub axle shaft where the bushing or needle bearing makes contact with the shaft. If your spindles have needle bearings, you also need to be sure that the roller needles are not dry, rusted or seized up, which is common: Does that answer your question? Moses

CDNDownUnder...You might try reaching out to ian cj10 through our Member email system. He's at Australia and may have insight into where you can source these seals...Moses

Bill W...Sounds like an interesting opportunity to test the SB intake elbow. You're good at matching before-and-after driving simulations. It should be an accurate test. Still in a holding pattern with SpynTec. I'm willing to install their kit, it looks well conceived and built. They may have all the publicity they need, though my approach would be a detailed how-to installation that could help their consumers. I'll keep you posted. Bearing end-play adjustment would be in the conversation with SpynTec, I'd like to know the rationale for a bearing preload instead of the conventional end play adjustment. Rear axle bearings on full-floating axles are preloaded. That may be their motive. I've got shelves full of OEM shop manuals with full-floating front axle bearing adjustments. None call for a final preload. Some settings are as close as 0.000"-0.004", typically 0.001"-0.006" or 0.001"-0.010". The procedures leading to any of these final settings involve a preload adjustment (to a specific torque) then backing off the adjuster nut enough to establish endplay. (0.000" is intended as the least amount of end play and can be easily misconstrued by some to mean a "preload". This is why most manufacturers go no closer than 0.001" end play.) In every case, this is a final end play figure after the outer lock nut has been torqued to factory specification. Following the OEM adjustment procedures, I like to see 0.002"-0.004" end play after final torque of the outer lock nut. Not more. 0.000" end play or, worse yet, a preload on the front wheel bearings will heat up the grease and bearings. A rear full-floating axle is different. The bearings carry considerable weight, the wheel hubs are non-steerable, and the hub bearings are lubricated by axle lubricant. Waiting for your findings on the SB intake... Moses

SomeBuckaroo…If the high idle is intermittent and not continuous, the intake gasket is an unlikely culprit. Depending on the leak’s position, however, this could be a source of extra oxygen in the O2 area. That would throw off the fuel trim. Follow up on the exhaust leak, regardless of whether it cures the idle speed issue. CO is not a gas to have in the cabin. I looked at the Remflex gasket, it’s similar to the gasket Borla furnished with the header on my 4.0L. The thick flanged Borla header has pluses and minuses. It’s very heavy and stiff. I’ve retorqued the manifold nuts and bolts at least a half dozen times since installing the header seventeen years ago. As for actual causes of the idle flare-up, a vacuum leak is a possibility. I had a vacuum leak on the XJ Cherokee that may be worthy of your attention. The vacuum hose to the bulb reservoir ran past the battery. Over time, the hose corroded and began leaking. The engine management system compensated under most driving conditions. My only clue was that the cruise control would kick out on a grade. The manifold vacuum signal was inadequate. I replaced the hose, end of problem. Yes, a smoke machine would be helpful for both the vacuum leak(s) and exhaust system check. Engine turned off and coil wire removed at the distributor cap, you could rotate the crankshaft slowly while the smoke machine feeds the intake and cylinders. When the exhaust valve opens at the leaking header tube(s), the header or exhaust leak would show up. In your case, there may be something else going on. If the idle kick-up speed is precise, especially after all of the parts you’ve replaced, I would check the HVAC controls and air conditioner wiring circuit. If the speed kicks up to 1000-plus rpm without the A/C compressor operating, this could be a false signal from the A/C circuit. The HVAC controls could cause the idle to kick up whether or not the A/C clutch engages. Worth checking, anyway. If the idle flares up to random speeds, the issue would likely be a vacuum leak or something else. On the 4-cylinder models, Mopar uses a power steering pump pressure sensor to kick up the idle when steering pressure goes up. Primitive and mechanical, the system senses the steering effort when the vehicle is stopped and the steering wheel gets turned. This boosts the pressure requirement and signals the PCM to raise the idle speed and compensate for the added load on the engine. Your issue could be similar if the A/C wiring circuit is bumping the idle speed to a somewhat consistent rpm. The A/C circuit may be activating without a compressor load, which would raise the idle rpm. It’s worth considering the HVAC controls, A/C pressure sensors or a wiring/ground issue. The PCM is looking for an “Air conditioning select signal” and an “Air conditioning request signal”…These would be related to the HVAC controls and dependent on A/C system high/low side pressures reading normal. So, when you’re trying to isolate the PCM signal, keep in mind what the PCM is watching for. Make sure your HVAC controls and pressure switch wiring function properly. Also note whether or not the A/C clutch/compressor is kicking on simultaneously with your idle speed step-up. For the rpm to stay at 1000 or so, the compressor would not be running and creating a normal load. Moses

SomeBuckaroo…If the high idle is intermittent and not continuous, the intake gasket is an unlikely culprit. Depending on the leak’s position, however, this could be a source of extra oxygen in the O2 area. That would throw off the fuel trim. Follow up on the exhaust leak, regardless of whether it cures the idle speed issue. CO is not a gas to have in the cabin. I looked at the Remflex gasket, it’s similar to the gasket Borla furnished with the header on my 4.0L. The thick flanged Borla header has pluses and minuses. It’s very heavy and stiff. I’ve retorqued the manifold nuts and bolts at least a half dozen times since installing the header seventeen years ago. SomeBuckaroo...As for actual causes of the idle flare-up, a vacuum leak is a possibility. I had a vacuum leak on the XJ Cherokee that may be worthy of your attention. The vacuum hose to the bulb reservoir ran past the battery. Over time, the hose corroded and began leaking. The engine management system compensated under most driving conditions. My only clue was that the cruise control would kick out on a grade. The manifold vacuum signal was inadequate. I replaced the hose, end of problem. Yes, a smoke machine would be helpful for both the vacuum leak(s) and exhaust system check. Engine turned off and coil wire removed at the distributor cap, you could rotate the crankshaft slowly while the smoke machine feeds the intake and cylinders. When the exhaust valve opens at the leaking header tube(s), the header or exhaust leak would show up. In your case, there may be something else going on. If the idle kick-up speed is precise, especially after all of the parts you’ve replaced, I would check the air conditioner clutch wiring circuit. If the speed kicks up to 1000-plus rpm without the A/C compressor operating, this could be a false signal from the A/C circuit. The HVAC controls could cause the idle to kick up whether or not the A/C clutch engages. Worth checking, anyway. If the idle flares up to random speeds, the issue would likely be a vacuum leak or something else. On the 4-cylinder models, Mopar uses a power steering pump pressure sensor to kick up the idle when steering pressure goes up. Primitive and mechanical, the system senses the steering effort when the vehicle is stopped and the steering wheel gets turned. This boosts the pressure requirement and signals the PCM to raise the idle speed and compensate for the added load on the engine. Your issue could be similar if the A/C wiring circuit is bumping the idle speed to a somewhat consistent rpm. The A/C circuit may be activating without a compressor load, which would raise the idle rpm. It’s worth considering an HVAC wiring or controls issue. Moses

FLCj8...You're welcome...If the fuel tank fits, that would solve the fuel pump issue. You could follow the GC factory wiring schematic and wiring color codes to bring a power feed to the fuel pump module. (Power is provided via a PCM signal.) Was there a hint that the module/fuel gauge sender could also provide the right fuel gauge reading in a CJ? Since you have both manuals, compare the fuel gauge ohms resistance for "Empty---1/2 Full---Full" at the CJ gauge and the GC gauge. If they happen to be close or the same, you may have that resolved as well. Be sure you have fuel tank skid plate protection if this all works out. In the end, see whether you can save and use the OBD (not OBD-II) port plugs. This would provide a diagnostics access for your 4.0L engine. It would be pre-OBD-II and require an older scan tool software and hook-up like DRB, older Snap-On or equivalent, but either way, that would be better than nothing. Otherwise, I would run diagnostics with an oscilloscope and/or a VOM. I have enjoyed the detail that my Autel MP408 with OAK accessories provides. You would be testing sensors and devices, not scanning, so the VOM tests would cover a lot of diagnostics. The FSM has those tests. Please let us know how "smoothly" (or not) the conversion goes. Share photos of your progress and solutions...You have some motor mount bolt-up differences between the 4.2L and 4.0L engine blocks. The block brackets from the 4.2L need slight modification to fit. (You will be using the 4.2L engine brackets to work with the OEM CJ motor mounts. The fit is otherwise stock.) The CJ-style engine driven fan is the usual approach unless you want to adapt the 4.0L GC fan plus its electric auxiliary fan system. (This is thermostatically PCM driven and requires correct wiring.) I've always used a CJ water pump, fan and radiator with shroud, but it's worth taking measurements and considering. The radiator shape and mounting system would dictate your choice. If you use the CJ radiator, make sure its A/C capacity for the added 4.0L horsepower. (Horsepower equals BTUs.) Keep in mind that the water pump on the 4.2L and 4.0L have opposite rotation direction. You will need to pick the right water pump for the fan and belt system. Whether or not you want/need to run the CJ drive belt system will be a question. (Do you currently have V-belt(s) or a serpentine belt on the '83 engine?) You can easily work your way through most of this. The timing cover bolts may need swapping to accommodate belt and power steering pump bracketry. Your manual transmission (presumably not an automatic) will require a crankshaft pilot bearing. The bigger focus will be wiring and emulating the GC's chassis/engine wiring needs. The PCM is hypersensitive to voltage measurements and needs clear voltage signals. Solid grounds are crucial. I strongly recommend that you rosin core solder and double heat shrink shield any wire splices between the EFI engine harness and the CJ wiring—no crimp connectors. The starter motor solenoid wiring is easy to adapt if you keep the 4.0L starter (better design than the older Motorcraft/CJ style). You have options in any case. You'll want to use the GC MAP sensor and other engine related peripherals. There will be the upstream O2 sensor for GC/4.0L, which you must use in conjunction with the GC's tubular header/exhaust manifold. Study the engine bay vacuum circuits for the Grand Cherokee (basic, nothing difficult here), the EVAP system, the O2 sensor, crankshaft position sensor wiring and so forth. You need to mate the 4.0L/4.2L EVAP systems to meet the CJ's fuel tank/filler neck EVAP requirements. This is not difficult but needs to be done safely and correctly. You have the advantage of holding onto the GC until the engine swap is completed. This provides access to donor parts. There won't be any surprises or need to buy missing parts. It's all there. Even in stock form, the 4.0L performance will be substantially better than the 4.2L. You may miss the 4.2L bottom end torque until you do the 4.6L stroker build. You'll be holding onto your 4.2L crankshaft and rods for that update. Pistons must be right for the rods that you decide to use (4.0L or 4.2L) when you build the stroker. You need the piston and rod combination that will provide the right piston crown height for the block's deck height. Crankshaft snout length is a concern when using an "early" (V-belt style) 4.2L crankshaft that has a longer snout length than the short snout (serpentine belt) 4.2L or 4.0L crankshafts. This can be remedied with a special spacer from HESCO...It's all part of a 4.6L stroker build, which has been done myriad times now. Moses

FLCj8...Good question on the MMO soak time. The advantage of an inline six (other than the vintage Mopar slant six) is that the pistons all stand vertically. With a teaspoonful of MMO per cylinder, a few minutes would be plenty. The engine isn't "seized", you simply want MMO to slip into the rings and coat the walls as you rotate the crankshaft (by hand with a socket and ratchet). The crankshaft rotation should be slow and easy. This will have the added effect of allowing the MMO to seep further into the rings. The spark plugs are removed, so there won't be cylinder pressure to push MMO out the exhaust ports. Some MMO will find its way there, so expect blue smoke on start-up. The goal is to protect the cylinder walls and lube the rings for initial engine start-up. There will be oil throughout the engine from priming. As for the cooling system, if the engine ran synthetic motor oil, I would guess the antifreeze/coolant got changed regularly. Confirm this and look for any residue in the cooling system. Freeze plugs are zinc-coated steel or brass, so I wouldn't expect bad plugs if the coolant looks clean. Your call here. Freeze plugs usually last between engine rebuilds. On crank and first start, watch the oil pressure. It should pop up immediately with the oil primed. Note the pressure, I want to see at least 50 psi on a cold Jeep inline six at start-up. It can be as high as 65-70 psi at a fast idle. OEM gauges are not perfect and can be off some. The '93 Grand Cherokee has full instrumentation and not an oil light. The rear main seal is elective but prudent. AMC/Jeep inline sixes with two-piece seals are notorious for rear main seal seepage/leaks. At mileage, they either seep now or will seep soon. When you have the engine drained and on a stand, it's not difficult to remove the oil pan and change the rear main seal. Turn the engine upside down for this work. Fel-Pro makes a terrific one-piece oil pan gasket kit for the Jeep inline six. (It's actually not a chore to change the main seal in the chassis with this pan gasket.) Read the Fel-Pro steps for installing the main seal. Follow Mopar guidelines for use of RTV and any other kind of sealant. It must applied at the main cap and block points according to the Mopar and Fel-Pro guidelines. If so, you will have a non-leaking, properly sealing rear main—for at least some time. I did my '99 4.0L rear main seal at 175K or so miles. At the same time, I installed a Sealed Power oil pump and new Melling screen. There is limited risk of an oil pump failure, but if you decide to change the oil pump for PM, use a Melling tool to install the screen. Make sure the new screen is installed correctly and riding at the correct angle. I did this in the chassis. It's much easier on the engine stand with the engine upside down. If you don't have the '93 GC FSM, get a CD or download FSM for the two-rail MPI 4.0L engine (1991-94). You'll need the FSM for the engine and chassis wiring harness diagrams, tuning and troubleshooting. Make sure you preserve the donor engine's wiring harnesses. On the '93 Grand Cherokee, this includes the full engine bay harness and wiring hook-up to the 60-Way PCM. Of course, you will be using the 60-way PCM from the GC. Good thing you have the entire vehicle. When using the '93 factory EFI/MPI system, you will want all wiring and connectors intact. You will also need the right inline fuel pump and a PCM power signal for the fuel pump. You can follow the Mopar wiring guidelines. In my Jeep CJ Rebuilder's Manual: 1972-86 (Bentley Publishers), I cover a 1991-94 Mopar two-rail EFI engine conversion using the Mopar EFI Conversion Kit. The kit's cost and parts availability (HESCO remains the source) have most owner/installers using the recycled donor engine's EFI components and wiring. You pore over the FSM wiring diagrams at the kitchen table and sort out how to mate the donor engine's EFI and wiring to your CJ chassis. HESCO can be helpful here, they understand that many owners use 4.0L donor parts. HESCO can provide some direction and parts like the correct inline fuel pump and filter. With the two-rail MPI/EFI system, you will be using an unrestricted fuel return line to the fuel tank. Moses

FLCj8...I'm sure your CJ-8 is a keeper! The 4.0L will be a major improvement, even more so when you stroke it. Good to consider how long the engine has set. If it's in the chassis still, I would vacuum all debris from around the spark plugs and remove the plugs. Fill a clean oil squirt can with Marvel Mystery Oil, and squirt a teaspoon or so into each cylinder. Remove the valve cover and squirt Marvel Mystery Oil over the valve rocker arms and into the valve spring areas. Not a lot, just a few squirts each. Remove the distributor cap. Bring the crankshaft to TDC on its compression stroke (timing mark aligned, #1 intake and exhaust valves closed). Mark the position of the distributor rotor, and remove the distributor so you can prime the lubrication system. You can prime the engine's lubrication system with an expensive pre-lube tank or a simple priming tool. With the priming tool, remove the ignition distributor. (You can make this tool if necessary from an old Jeep distributor shaft.) Be sure the crankcase is full of oil. If it looks oxidized, drain and refill the crankcase. Otherwise, if the engine oil looks okay, leave it for the priming and initial start-up of the primed engine. A 1/2-inch, variable speed drill motor works best here. Carefully and slowly rotate the oil pump drive, keeping the priming tool engaged with the oil pump. (Do not damage the oil pump tang.) You should feel resistance—that's oil pressure. Continue rotating the pump and watch the valve train for oil. After oil appears at the valve rockers, pause the priming and rotate the crankshaft 180 degrees. Prime again until more oil appears. Stop. Rotate the crankshaft 180 degrees further. Prime again until more oil appears. Stop. Rotate the engine 180 degrees further. Prime again until more oil appears. Stop. Rotate the crankshaft slowly back to TDC on its compression stroke (180 more degrees). By now, there should be oil at each rocker arm. All parts should have oil. If you can reuse the valve cover gasket do so. Otherwise, replace it. With the crankshaft at TDC on the compression stroke, reinstall the distributor with the rotor pointing exactly where it did when you removed the distributor. You may need to align the oil pump tang with a large screwdriver to get the distributor to drop into the correct position. Install the spark plugs and wires. That's as good as it gets for initial start-up, you have oil everywhere and no resistance at the rings and pistons. The engine will smoke at start-up as the Marvel Mystery Oil passes through...If you're starting the engine in the Grand Cherokee chassis, get rid of the fuel in the tank. The fuel will be stale and potentially damaging. Siphon it all out if possible to avoid the need to drop the tank. Put five gallons of fresh fuel in the tank with a can of Sea Foam. The fuel filter should be changed. That's it. Start the engine and see what you have. After running the engine long enough to warm up completely and sound good, shut it off and check the oil. If it's still clean and looks good, being synthetic, I would leave it in the crankcase until after you get the engine running in the CJ-8. Moses

You're welcome, SomeBuckaroo...The fuel rail pressure test would be an interesting angle. Be aware that your single-rail system uses a damper on the rail. Many mistake this for the pressure regulator on pre-OBDII engines with the two-rail injection system. Your pressure regulator is at the fuel tank module. The wild cards would be whether the damper compensates for the pulses you describe and if the fuel pressure regulator is sensitive enough to offset these pulses. It's not likely that subtle variances in injector pulses would be picked up by either the damper or pressure regulator. So, it's worth experimenting. Give it a whirl and let us know if this is a valid way to detect fuel flow issues per injector! Moses

Julio...First, regarding the fuel gauge level, check your ground at the fuel pump module and fuel tank. Then check the gauge sender signal to your gauge for ohms resistance. If you have power to your gauges, the fuel gauge needs to receive an ohms-resistance signal from the fuel gauge sender. The ohms-resistance should be 0 ohms when the fuel tank is empty (gauge float in lowest position); 44 ohms when the tank is half full (float raised halfway); and 88 ohms when the tank is full (float in full up position). Here is a rough PDF of the troubleshooting for the gauge. I scanned it from my 1989 Jeep FSM. This is as far as I can scan without breaking the book binding. For more details, pick up a CD or print copy of the FSM for your YJ Wrangler: 1989 YJ Fuel Gauge and Sender Troubleshooting.pdf Since the gauge worked before, either the sender's float is not rising (stuck, binding, an open in the wiring or the float is defective) or the electrical connection from the fuel module to the gauge harness has an "open" (not making proper contact in the connector). If troubleshooting from the PDF does not solve the issue, this new gauge sender is likely defective. As for your consistent idle speed rise to 1,000 rpm after start-up, the PDF below is coverage of the idle switch and the ISA motor. The step up in idle speed could be an idle switch issue or ISA motor related. Again, the FSM for your Jeep will outline these steps clearly and walk you through how to troubleshoot and stage the ISA motor, the idle stop and the idle step-up switch if so equipped: 1989 YJ 2.5L ISA Motor and Idle Switch.pdf If you have A/C or power steering, or both, the FSM clarifies how the A/C and power steering idle step-up speed works. On that note, make certain that the Power Steering idle step-up speed is working properly. The 2.5L models are designed to have the engine speed step up when you apply the power steering at an idle. The reason is that these engines don't have the idle torque to handle the load created by turning the steering wheel and placing a power steering pump load on the idling engine. Without the idle speed step up, the engine would stall. This circuit works through the A/C circuit, which also steps up engine idle speed when the A/C clutch engages. In simple terms, when the power steering signals a high enough pressure (pressure range listed in the PDF below) with the engine idling, the ECU will kick up the idle speed (at the ISA motor) to keep the engine from stalling. If the pressure switch signal or P/S pump output pressure is too high, this would bump up the idle speed when the P/S pump starts putting out pressure (which could be the 5-second lag). The A/C compressor clutch engaging would also be a signal to raise the engine idle speed. A problem with the engine idle speed stepping up could be too much pressure at the P/S switch or a defective power steering pressure switch. Even without turning the steering wheel, the idle speed might kick up. Turning the steering wheel with the vehicle stationary will raise the P/S pressure. A steering gear internal pressure issue could also do this. So could a power steering pump that puts out too much pressure at an idle. I would put a hydraulic pressure gauge on the port where the power steering switch threads into the system. See what the actual P/S pressure is at an idle with and without turning the steering wheel. If pressure is above normal with the steering wheel stationary, that would cause the idle speed to kick up. If pressure is not above normal, I would suspect that the pressure switch is defective or there is a wiring issue in either the A/C circuit or the P/S pressure switch circuit. A quick test would be to simply disconnect the wiring connector at the P/S pressure switch and see whether that stops the idle from stepping up 5-seconds into running. That 5-seconds might be how long it takes the P/S fluid to boost pressure at the pressure switch. Causes of high pressure at this port could be a steering gear issue or even a P/S pump that puts out too much pressure at low engine speeds. Here are the FSM comments about the P/S switch function and the pressures. The switch is inline near the power steering pump: Your Jeep is now older technology, as you know. I depend on my 1989 Jeep FSM set (Engine, Chassis & Body volume plus the Electrical volume) for troubleshooting the 1987-90 2.5L Jeep TBI systems. I would not attempt to work on any of the 1984-90 AMC/Jeep vehicles with the 2.5L TBI engine without an FSM. Do you have copies or CDs that cover your Jeep? Any 1987-90 Jeep FSM set would work for your Wrangler. 1984-90 XJ Cherokees use this same TBI system. There were minor changes over the years, so 1987-90 would be better coverage. I just found this at eBay for any 1987-90 YJ Wrangler owner wanting to work on his or her vehicle. This is essentially the same as my '89 Jeep print FSM. Bishko apparently combines both volumes into one CD-ROM or download. If so, for $30, this would be easier navigation than a print manual and have all the answers an owner needs: https://www.ebay.com/itm/132408471190. Moses

SomeBuckaroo...Sounds like a good strategy for ruling out uneven or restricted exhaust pulses. As for pulse width, yes. The injectors all receive the same PCM pulse width signal. The duration of the pulse width is controlled by sensors and fuel trim. Rail fuel pressure is (should be) constant at each injector. As for the actual fuel volume flowing through each injector, that would have to do with the individual injectors and affected by nozzle clogging/restriction or a restricted injector filter/screen. If there is a restriction, the PCM adjusts the pulse width to compensate. The PCM does this based on receiving the O2 and input from several other sensors. This system is not intuitive. It is strictly mechanical. There are software PIDs and algorithms that control air/fuel ratios and injector pulse width. Moses

SomeBuckaroo...I watched the six videos through with keen interest. Wave patterns for each channel need to be viewed individually when comparing cylinders. From what I can see, the valve opening events and related changes in pressure look normal as does the compression. There is no loss of compression toward the top of the in-cylinder readings, even when you accelerate or snap the throttle. In these tests, what is the actual compression peak in psi at an idle and at snap throttle? I have no concerns about the spark firing lines. When you accelerate, the cylinder pressures rise, and the voltage requirement to combust air/fuel is affected by increased resistance. The firing lines rise accordingly. This indicates that the ignition is meeting the firing demand. The rise is uniform, as expected, since the same coil is firing all six cylinder on a distributor ignition. (Compression psi and firing resistance are nearly equal per cylinder, too.) If this were a coil-on-plug engine, there would be some variation (likely minor) in the spark firing line heights for the cylinders. Deceleration causes the erratic spark lines as the ignition firing voltage varies here. The firing load and voltage demand are rapidly dropping, and there is a fluctuation in cylinder pressures with the decreased load, closed throttle plus the arbitrary cutting off of the air/fuel supply with an MPI/EFI engine. (There's no "venturi effect" like with a carburetor. With EFI, the fuel flow is electronically cut off during deceleration to reduce emissions and wasted fuel.) This doesn't look unusual. It would appear differently with my MP408 scope and software. Your "pure" lab oscilloscope can't leave anything alone...and you get to do more math. Regarding your hooking up a spare injector to simulate the firing of the injector during in-cylinder transducer testing, two things are going on. First, the PCM sees a completed injector ground activation signal and reads it as normal, regardless of whether fuel is flowing through the injector or not. (The system is not sophisticated enough to sense fuel pressure changes at individual injectors; it only monitors fuel pressure for the entire common rail.) Your extra injector is not hooked up to the rail fuel supply. If it were, there would be fuel spewing from the injector's nozzle with the engine running! You're running the spare injector dry, which raises the question of whether an injector needs fuel flow to lubricate the pintle, a topic for another thread. Secondly, the crankshaft position sensor (CKP) is oblivious to any "pulsing" of the crankshaft or injector firing. As long as the PCM gets a TDC signal from the CKP, all's good. Your spark timing varies as it should under different engine loads and throttle positions. I see nothing unusual here. Intake pressure pulses are stable at idle and vary as expected with the throttle snap and deceleration. Your scope is detailed here. As for injector pulse width and fuel flow, even though you remotely hooked up an injector to represent the dead hole/cylinder, that circuit is functioning. The spare injector simply did not receive fuel from the rail. You also did not have fuel flowing through the intake port at the tested cylinder since you disconnected that injector at the harness. That's a good thing, since you do not want fuel inside the cylinder while you're using the in-cylinder transducer! Always disconnect the injector for the cylinder being tested with an in-cylinder pressure transducer. As for no codes and no PCM sense that the false injector was in place: If you had left the cylinder's injector hooked up during the in-cylinder transducer test, the steady stream of unburnt fuel passing through the cylinder would have thrown off the O2 readings. Raw fuel passing out the exhaust would likely throw a code for a cylinder misfire. (Also, the system would try to compensate with a fuel trim adjustment, making the operating cylinders run lean.) Injector pulsing and fuel flow work independently of the ignition system. You grounded either the spark lead or spark plug for the test cylinder. That cylinder could not fire without fuel or spark...but the PCM did not "see" a problem since both the injector pulses and spark took place. The spark firing line for that cylinder would reflect the grounded lead or grounded spark plug "firing"—without a load. You would not get a "normal" spark firing height from that cylinder because there was no cylinder pressure or load affecting the spark plug. Summing it up, your compression and power stroke (expansion) patterns look good and uniform, no sign of compression loss. The valve opening and closing events and patterns are good. There is a consistent, slight "spike" near the exhaust/intake valve overlap point during deceleration after the throttle snap. This could be a function of the exhaust pulse change, maybe pressure changes in the exhaust system. There's no indication of a "clogged exhaust". Each cylinder shows this bump. Is the exhaust system (header/pre-cat, muffler, catalytic converter and pipes) "original"? Using your pulse sensor in the tailpipe, run the engine at an idle then a steady 2500 rpm for a moment. (Stay away from the engine driven cooling fan!) Compare the exhaust expulsion pressure waves and see whether the exhaust pulses look normal. Compare the pulse sensor readings at an idle, 2500 rpm and also a snap throttle test. You're looking for a significant restriction. A restriction affecting idle stability is unlikely. Restriction causes poor fuel mileage and a power decrease. In-cylinder transducer testing is for mechanical trouble. Spark firing lines, base and advanced spark timing (which are normal in this case) and injector flow are tune related. Your main concerns here were the in-cylinder wave form for pressure peaks and uniform rise and drop in pressures, the valve opening and closing events (reflecting cam lobe profiles, valve sealing and valve timing), the shift from pressure to vacuum and vacuum to pressure, and your intake and exhaust pulses. The intake pulse readings look normal, indicating that you whipped the air leak at the throttle body. I would run the simpler exhaust pulse test with a snap throttle. This will rule out any exhaust restriction. Then move on. If the MAP and O2 sensors are functioning correctly, any remaining idle instability (beyond what's "normal" for a Jeep 4.0L MPI engine) would have me looking for an upstream exhaust leak at the header/exhaust manifold. (The 4.0L exhaust manifolds are notorious for cracking between tubes.) Next I would flow test and compare the fuel injector flow rates. Given your mileage, and despite the new engine, either of these possibilities are worth checking. I invested in my Autool C200 6-cylinder fuel injector tester for this troubleshooting scenario. At high mileage, the OEM Siemens injectors needed ultrasonic cleaning and new filters but were otherwise fine. Even at nearly 200K miles, I trust these OE injectors for flow and reliability. They're more predictable than Brand-X offshore injectors that many owners buy on the cheap at Amazon or eBay. At the time, the C200 machine cost about the same as a full set of Bosch replacement injectors. The machine should last forever with the volume of gasoline injectors I will clean. Still very much worth the investment. Moses

Footnote for our scope tests: From experimenting and reviewing scope results and other users' experiences, it is clear that the in-cylinder pressure transducer cranking tests (engine not running) should be done with the throttle closed. This is unlike traditional cranking compression tests where we hold the throttle open for maximum available air. The pressure transducer readings are far more stable with the throttle valve closed. SomeBuckaroo...For those following this testing and your original concern about a high and erratic idle, the throttle shaft air leak is a concern with any higher mileage EFI engine. For those wanting a quick test for throttle shaft leaks, try this: With the engine idling, a light mist of WD-40 at the throttle shaft ends will change the idle speed momentarily if a leak is present. (Keep WD-40 spray away from engine heat!) Good work here. As for the scope patterns, the CKP (your lower reading) looks like the pulse/phases from the flywheel's Hall effect. There is not a single TDC spike but rather multiple spikes for the same cylinder. As for this CKP reference, you really don't need it. True TDC with an in-cylinder pressure transducer is at the peak of the compression rise. The highest pressure point in a cylinder, the peak of your pressure waves, is the piston at TDC on the compression stroke. Instead of a channel devoted to the CKP sensor, I would do spark firing lines on that channel. See how your spark timing aligns with the pressure peak TDC. At an unloaded idle, I would expect 12-14 degrees of spark advance. At least 10. If your distributor is indexed properly with the crankshaft timing mark, ignition timing (advance degrees) is also a clue to whether the valve timing is correct. In-cylinder pressure testing can identify the valve opening and closing points. To do this, bring your scope pattern to view two of the highest compression points. These TDC points are at the top of the compression stroke, so between these two peaks is a distance of 720 crankshaft degrees. (This is a 4-stroke engine, two crank rotations per four stroke cycles.) If you have cursors, stage the curses at the two TDC pressure peaks and also the two BDC (bottom dead center) points between these pressure peaks. Start at the left with the first downslope from peak pressure. This is the Power Stroke. Near BDC, the exhaust valve begins to open for the Exhaust Stroke. The piston rises with the exhaust valve open, so pressure is slightly wavy and on a horizontal plane or plateau as the piston pushes exhaust from within the cylinder into the exhaust system. (This area of the pattern will reveal an exhaust restriction.) Hot gases are being pushed out of the cylinder. Then comes the valve overlap opening between the exhaust valve closing and the intake valve opening. The pressure goes negative (waveform drops) as the intake valve opens, beginning the intake stroke down near BDC. (The cylinder is filling with the intake air/fuel mixture.) Finally, you see the Compression Stroke as the waveform sweeps upward to the second pressure peak at TDC on the compression stroke. You have the cursors set at 180 crankshaft degrees apart. If you know the valve timing events (degrees) of your camshaft's profile, you can identify where the valve opening and closing events should take place. You can check the valve timing by plotting the intake and exhaust valve opening and closing degrees. Match up the crankshaft/camshaft degrees with cylinder pressure changes. Keep in mind that the camshaft rotates at 1/2 the speed of the crankshaft and 1/2 the number of degrees as well. The waveform will approximate the valve opening and closing points or degrees. (Flat tappet lifter ramp-up and other variables prevent a pinpoint reading of the camshaft timing and valve opening and closing points. A roller camshaft would be more accurate.) This will be close enough to indicate whether the valve timing marks are aligned on the sprockets or if there is slack in the timing chain (retarded valve timing). Your parts are new, and you were careful installing the valve timing set. There should be no issue here but verify for practice. If valve timing checks out, so far I don't see any abnormalities. Yes, it would be helpful to see full pressure spikes under snap throttle. The cylinder pressure rises considerably, and if telltale piston ring or valve leakage exists, it should show here. Compare the peaks of the snap throttle waveform. Cylinders should be uniform. When cylinders seal well, the waveforms will be equal if the ignition timing and fuel mixtures are correct. As for your cranking pressures versus these running engine pressures, they can be compared. You did the relative (cranking) compression check. That was without firing the engine. Running cylinder pressure is with fuel mixture in the cylinder on its compression stroke and firing for the power stroke. Cylinder pressure will spike with the snap throttle. See what pressure values the transducer reveals. There is nothing apparent yet that would contribute to a rough idle. The intake pulses seem to match per cylinder. To rule out a mechanical issue like valve leakage, weak valve springs or piston ring seepage under load, we'll need to see the entire snap throttle waveform. Then check and compare all six cylinders. When you get the next round of waveform patterns, I will help break down the cylinder patterns and pinpoint any signs of compression loss from either the rings, leaking valves (weak or broken valve springs, poorly seating valves, etc.) or even the head gasket. This will show up distinctly at either an unloaded idle or snap throttle loads and deceleration. Your in-cylinder pressure transducer can pay for itself here! We've been ruling out mechanical issues. The ignition has been spot on in other tests. Did you check the intake manifold-to-head gasket for a leak? (The WD-40 test works well here. Avoid heat with the spray mist.) Complete the cylinder pressure tests, keep using the intake pulse sensor. After that, among the few concerns left would be an exhaust manifold leak affecting the O2 readings or the fuel injectors. Have you checked the fuel rail pressure? Moses

Chris S...See my comments below...Welcome to the forums!...Moses

Vac7349...You have an AMC 258 inline six. The ignition is conventional. The carburetor, too. Is there an issue cranking the engine over? What symptoms are you trying to address? Won't crank? Won't start? With more information, I'd be glad to make suggestions. Let us know where you have taken the process. Moses

I like it, Mr Rex! The WC was an eighties era bump that the Mustang GT and H.O. models got. This should work well for your application. Jeep CJs used the standard T-5. Advance Adapters would upgrade that transmission with a new T-5 World Class. The C-10 pickup will be greatly enhanced by the overdrive. You can expect a gain in fuel efficiency with the correct axle gearing. Moses

MrRex...I'm looking forward to hearing more about the Tremec 5-speed. What's the torque rating? Is this the T-5 rated 300 lb-ft torque? Or heavier duty? As for the SM420, it is a classic (1947 to early 1968 GM trucks). The market would be restorers of vintage 1955 Second Series through mid-sixties 2WD GM light trucks. It does not have the E-brake for a medium duty truck. It won't work with a torque tube rear axle (1/2-ton 1947 through 1st Series 1955). If it needs gears, that's a cost issue. The SM420 transmission was once the go-to for vintage Jeep V8 swaps using a Chevrolet or other GM engines. (The SM465 has become the updated choice due to availability.) The more common SM420 has a 7.05:1 compound 1st gear ratio for exceptional reduction. 2nd through 4th gears are synchromesh with a relatively low 2nd gear ratio for normal startups...The mate-up would be easy to a Chevy V8, V6 (4.3L) or a Buick engine with a stock Buick/GM bellhousing. Advance Adapters has the mate-up to the Spicer Model 18 or 20 and the Dana 300 transfer cases. Any Members or Guests interested in a "rebuildable core"? Using the information I provided regarding applications, consider running an ad at Craigslist. Shipping is costly, so a local Craigslist buyer would be practical. Moses

masonmoa...Very pleased that the Z-117 does work for your 225 Dauntless. All of my research and data pointed to this flexplate/flywheel crankshaft pattern. Does the 700R-4 torque converter fit up properly? Is the converter hub and crankshaft flange a match-up? The Jeepster/GM THM400 and 700R-4 should share common features. Are you using a conventional or lock-up converter? The original Jeep/GM THM400 converters were non-lockup style. (700R-4 was the lock-up emissions era.) Buick did have an exotic twin-pitch stator for its Turbo 400, but that converter was not used in Chevrolet, truck or Jeep applications. Kaiser, I'm sure, wanted things simpler. The Buick 350 V8 with THM400 and a conventional torque converter was available in the Jeep Wagoneer and J-trucks (1968-71). You'll need kickdown function. A simpler route for this is the Painless or similar setup for the 700R-4. These wiring kits with a kickdown switch simplify installations like yours. You'll like the 700R-4 overdrive when you get this all sorted out. With the CJ axle gearing, the overdrive is valuable. Regardless of your converter choice, my suggestion is a stock or lower stall speed converter for both compression braking and immediate hookup. High stall converters do not work well in a 4x4, and they burn unnecessary fuel. Let us know how your 700R-4 conversion turns out and the parts involved. This would be of interest to other Jeep owners wanting to convert a Buick V6 225 or odd-fire 231 to a 700R-4. Advance Adapters has mated 700R-4 and 4L60E (electronic version) transmissions to a variety of transfer cases. Moses

SomeBuckaroo...Thanks much for all the details on this product line. Rotkee is trying! Your workaround with the compression gauge adapter is what I envisioned. Thanks for testing and validating. Rotkee may want to add a similar (common) adapter to its product line. Yes, the 3/4" thread lengths on Jeep and many other spark plug applications do need consideration. Rotkee and others try to "universalize" the tool. In the process, they use a shorter reach to fit cylinder heads/spark plug holes with shorter thread depth. If they made the threads 3/4" length, the adapter or transducer would interfere with the piston crowns! I would use Rotkee's adapter hose all of the time to get the transducer away from the warm-to-hot cylinder head. I am looking forward to supporting this vendor! They build quality products. Moses

SomeBuckaroo...Looks "industrial strength". Interesting that the transducer threads into the cylinder head/spark plug hole. Some questions: 1) Any instructions or comments about engine (cylinder head) temperature when testing with the transducer? Does the transducer look rugged enough to handle some cylinder head casting heat? Most transducers have a temperature operating range. Of course, there's no combustion in the cylinder being tested, so the concern would be the cylinder head temperature. 2) The transducer looks stout. The barrel's diameter should fit most spark plug reaches with a 14mm spark plug thread size. Is the "brake hose" with fittings an adapter for threading into the spark plug hole and remotely mounting the transducer? That would make sense for applications with narrow spark plug access like a "hemi" cylinder head. 3) Does the company offer adapters for other spark plug thread sizes? Many motorcycles and older Ford engines have odd thread sizes. This would not be a deal breaker. There are adapters available to mate 14mm thread size compression gauges to these odd size spark plug threads. The adapters could be used with these tools. 4) The test connectors do include standard BNC for hookup to common scopes? Electrical connectors look sturdy. They didn't skimp on product. You got a box full! Good to support companies trying to build affordable, quality tools and equipment. Moses

SomeBuckaroo...This is an exciting example of your oscilloscope being used to test the engine's mechanical condition. You did a stellar job and got useful results for diagnostics. The amp clamp starter current wave form is not abnormal or exceptionally noisy. This is a higher amperage draw and may have to do with our clamps. While a low pass filter could help, this is not critical. Peak voltage heights are more important, which you clearly captured. Below is a screen shot of the Autel MP408 displaying the 4.0L Jeep starter draw with my Autel (Hantek) 650A clamp. The pattern, especially if I were to stretch it out, looks much like yours: Your initial test of relative compression is revealing. Though relative, this is true cranking compression. Your earlier standard compression gauge and leakdown tests provided a baseline for using #1 cylinder as a reference. (You can do simple math to approximate the compression on the other cylinders.) The in-cylinder pressure transducer that you use later is also real cranking psi...You went from using a conventional compression tool to making the same observations with the transducer. This has made your oscilloscope that much more versatile. Note: It is possible to get a "normal" compression gauge reading with a cylinder that has weak or broken valve springs. The Schrader valve in the typical compression gauge allows the gauge to "pump up" to peak compression and hold it—even when several crankshaft rotations may have much lower compression. By contrast, your new in-cylinder pressure transducer should not have a Schrader valve. The transducer will show pressure changes with each rotation of the crankshaft. The in-cylinder transducer should only be used with a hollow hose or adapter tool that does not have a Schrader valve! The repeat pattern is similar, which rules out a fluke chance that the starter motor's condition is not up to par (bad sector, field coils, bushing drag or other issues). As for drooping compression, what stands out for me is #1 cylinder and #4 cylinder in the 1-5-3-6-2-4 firing order. There's nothing earthshaking yet a clear drop at #1 cylinder. #4 is slight; #2 is negligible. Compression variance does not account for a "rough idle" condition. Yes, you are correct that the intake vacuum reading should be different (higher negative pressure or vacuum) with the throttle closed. Let's look at the intake negative pressure with the throttle closed through a cranking test. Again, I purposely suggest the cranking test because the engine is not running. Intake pulses will be strictly a reflection of the engine's mechanical functions. What I do see is fluctuation in the intake pulsing, which also makes it worth testing with the throttle closed. Without any interference from ignition/combustion and a power stroke, the intake pulses do not show equal vacuum per cylinder. Look approximately 3/4ths time interval between cylinder compression peaks. This is the intake cycle when air/fuel is drawn into the cylinder, followed by the intake valve closing and the compression stroke. By cylinder firing order, the vacuum is not equal per cylinder. If this persists with the throttle closed, I'll share possible causes for vacuum loss per cylinder. Let's compare the closed throttle cranking results first. The in-cylinder transducer results look really good! Again, your in-cylinder transducer test does show #1 and #4 cylinders with a slight drop in compression. Let's see what this looks like with the engine running, testing one cylinder at a time front to rear. Cranking tests are different than readings with the engine running. Presumably, you ran the cranking in-cylinder transducer tests with all spark plugs removed. Since this is just isolating and testing individual cylinder pressures at a slower cranking rpm, you eliminate factors like reciprocating mass imbalance. (Mechanical imbalance would have to be extreme and obvious to affect cylinder pressure readings.) Unless the crankshaft, damper or flywheel/clutch are way out of balance, engine reciprocating parts imbalance is not likely with an inline six-cylinder engine. Footnote: An inline six is an optimal design for harmonic balance. Imbalance phasing issues would not be a factor unless the crankshaft, flywheel/clutch, crankshaft pilot bearing, damper, flexplate or torque converter are defective. In general, harmonic vibration (with the engine running) would raise questions like whether the engine has its original damper and flywheel/flexplate, clutch cover and disk imbalance or whether the flywheel has been resurfaced. Overall, the crankshaft and its reciprocating mass must be in balance. For the in-cylinder pressure transducer test with the engine running, the Jeep 4.0L engine will run on five cylinders as you move through the test at each cylinder. At each cylinder, test the engine running at idle speed and a snap throttle. This will show both idle operating pressures and the pressure changes under a brief compression load. Recall the snap throttle impact on your spark plug firing lines earlier? Watch for the corollary here. You must be excited about the diagnostics capability these tools provide... Moses

Masonmoa...Your question is well reasoned...Some manufacturers will not drill a pilot bearing/bushing bore for their crankshafts intended for use with an automatic transmission. Their manual transmission crankshafts have a drilled bore to accept a pilot bearing. This gets discovered while trying to install a manual transmission in place of an automatic. However, this is not typical for GM. The only crankshaft that shows up for the 225 Jeep applications is the 1357898 casting. And we know your crankshaft has the pilot bore for the CJ's manual transmission pilot bearing/bushing). GM and others generally make a standard diameter indexing hub for the flywheel and flexplate. This matches the hole diameter at the center of the flywheel or flexplate. Are you finding that the bolt circle/pattern is correct but these flexplates are not fitting onto the crankshaft's indexing hub? I just went to the Clegg Engines website. (Clegg is a large engine reman facility.) Their crankshaft catalog lists odd-fire Buick 225/231 V6s this way: 64-67 BUICK 225/3.7L V6 Crankshaft Kit (BU-10220-225) 75-77 BUICK 231/3.8L V6 Crankshaft Kit (BU-10220-231) For the odd-fire 225 engines, here are the core casting numbers Clegg associates with their kit. These numbers are also 1975-77 (early '77) odd-fire 231 crankshaft castings: 1255645, 1357898, 1378351, 1378354, ODD FIRE ENGINES [Note the 1357898, which shows up for both the odd-fire 225 and the 1975-77 odd-fire 231 V6s.] 1967 was the last year Buick used the 225 V6. Kaiser bought the tooling and continued building these engines. This is likely why the 1357898 crankshaft is shown for all Dauntless applications. This might have been the 1967 prototype casting. Both crankshaft kits spec as Clegg's part #10220. The 225 and 231 odd-fire distinction may simply be for catalog purposes due 1) to Buick's V6 hiatus from 1968-74 and 2) the bump in cubic inch displacement when Buick bought back the tooling from AMC and transformed the 225 into the odd-fire 231. Clegg will accept a 1357898 core for either engine application. There is no distinction for "Manual" versus "Automatic" transmission on any of the Buick listings. All odd-fire crankshaft cores either have the pilot bearing bore or, in the worst case scenario, can be drilled for one. Your current concern is the crankshaft flange's indexing hub diameter and the bolt circle diameter. Since Kaiser/Jeep was using the THM400 behind the 225, as well as with manual transmissions, it's highly unlikely they would have the crankshaft flanges machined differently for each application. (The first Dauntless 225 V6s were assembled Buick crate engines.) The usual protocol for GM was one crankshaft that fits all applications. Moses