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  1. The owner of a 1998 Jeep Wrangler had several questions about the use of a CompCams 252H grind camshaft in a Jeep 4.6L stroker inline six engine build. His engine core is a 1998 Jeep TJ Wrangler 4.0L...Here is our exchange. My comments are in red: Keith M.: I’ve seen some posts, including on Comp Cams’ site, that say the head on the ’98 has different size valve stems than other years and that cams that will work on other years won’t work on this one. I’m pretty confused by what seems to be conflicting and unreliable information. Moses: I’m not clear why there is so much confusion. CompCams should know parts interchangeability and sizing. 4.0L valve stems are available in both standard size and oversize for a given engine, which may account for the confusion. Parts interchangeability spans many years. Exhaust or intake valve head diameters may change while stem diameters remain common. Federal-Mogul is a well-known reman engine industry parts supplier. We’ll use F-M as a reference source: https://www.fme-cat.com/overlays/part-detail.aspx?brand=SP&PartNumber=V-2527&pt=Intake%20Valve&lu=1998%20JEEP%20WRANGLER&vin= [Intake valves] https://www.fme-cat.com/overlays/part-detail.aspx?brand=SP&PartNumber=V-4554&pt=Exhaust%20Valve&lu=1998%20JEEP%20WRANGLER&vin= [Exhaust valves] https://www.fme-cat.com/Application.aspx?year=1998&make=JEEP&model=WRANGLER&cat=Engine&engbase=4.0L%20L6%20242cid&ga=Y&back=true [Overview of intake and exhaust valves] https://www.fme-cat.com/overlays/part-detail.aspx?brand=SP&PartNumber=VK-216&pt=Valve%20Spring%20Retainer%20Keeper&lu=1998%20JEEP%20WRANGLER&vin= [Valve retainer keepers] https://www.fme-cat.com/overlays/part-detail.aspx?brand=SP&PartNumber=HT-2011&pt=Valve%20Lifter&lu=1998%20JEEP%20WRANGLER&vin= [Lifters are the same over all inline Jeep/AMC sixes] A concern with camshaft installations would be the rocker arm ratio. See the rocker arm interchangeability in this listing. AMC/Jeep inline six rocker arms are essentially the same with the same ratio: https://www.fme-cat.com/overlays/part-detail.aspx?brand=SP&PartNumber=R-905A&pt=Rocker%20Arm&lu=1998%20JEEP%20WRANGLER&vin= Pushrods for 4.0L engines fit the full range of 4.0L years. They are available in different lengths because the rocker arms are non-adjustable. I have discussed this at length in the forums and magazine; see https://forums.4wdmechanix.com/topic/1155-42l-re-build-77-cj-7-project/ and my reply comments from December 25, 2018 and forward. Read the details on fitting the right length pushrods. Here is the F-M parts listing for 4.0L pushrods in a standard (OEM baseline) length. There is selective fit application coverage to compensate for engine block and cylinder head deck height changes, head gasket thickness and so forth: https://www.fme-cat.com/overlays/part-detail.aspx?brand=SP&PartNumber=RP-3275&pt=Push%20Rod&lu=1998%20JEEP%20WRANGLER&vin= Keith M.: I want to use the 252 cam you recommend in your video but I haven’t been able to find a video with specific part numbers. Some of the information I’ve seen indicates that I need to change the valve springs if I go to that cam, other places I don’t see that. I need a timing set but have new lifters so I’m trying to get a package if I can but don’t want un-needed parts. I’m also unsure of which cam works with fuel injection as I have been told this makes a difference. Moses: Sounds like you just need the 252H camshaft if your new lifter set is compatible. If the lifters are OEM replacement, ask CompCams tech if OEM lifters will work with the 252H camshaft. Typically, the camshaft kit includes the cam and lifters, but if CompCam simply uses an OEM replacement type lifter, you could save some here. The 1998 4.0L upper valve train (valves, retainers, keepers, rocker arms and such) should be readily compatible with your 252H camshaft choice. You do need to use the correct length pushrods to attain the right lifter preload as described at the forum exchange and magazine articles. If lifters are the same, you can see whether CompCams is willing to sell the camshaft by itself. They may not warrant the camshaft if you don’t use their lifters…Always use engine break-in lube additive (Lucas, CompCams, etc.) with ZDDP to assure proper seating of the lifters with the camshaft lobes. You still need a timing set from whatever source plus correct length pushrods if the OEM pushrods are not the correct length. As for the PCM compatibility, there is the issue of Coil-On-Plug engines requiring a different camshaft than the 252H. Your engine is not C-O-P, it has a distributor and earlier PCM programming. I’ve not heard of anyone getting an engine code from a 252H camshaft installed in a pre-C-O-P engine like yours. If I were to build my 4.0L 1999 XJ Cherokee distributor type engine into a stroker, I would use the 252H grind camshaft rather than use a stock OEM replacement. I have used the 252H grind with EFI truck engines as far back as a Ford 300 inline six MPI engine (1987). The 252H grind has also been tested repeatedly by Tony Hewes on pre-C-O-P EFI/MPI 4.6L stroker builds. Keith M.: This package would be fine, under specifications it says it works on years 1964-1998. But I can’t be sure that’s correct really, because of the fuel injection and possible valve stem issue: https://www.compcams.com/high-energy-206-206-hydraulic-flat-cam-sk-kit-for-amc-199-258-4-0l.html If I had to replace valve springs I’d use this kit: https://www.compcams.com/high-energy-206-206-hydraulic-flat-cam-k-kit-for-amc-199-258-4-0l.html In specifications it says 1964-1998, but under Installation Notes it states ‘K-Kits will only work in 1964-88 models due to different valve stem diameters” Moses: Valve springs and retainer sizes are governed by the valve stem diameter. This appears to be the reference here. Logically, you do need to match valve springs and retainers to the valve stems and cylinder head spring seats. For your purposes, you only need to use the right diameter 4.0L valves, matching springs and retainers for your cylinder head casting and model year choice. Approach the valvetrain like you’re rebuilding a stock 4.0L engine. Choose replacement parts for the cylinder head casting and block casting involved. Keith M.: And somewhere in here there’s a review for a kit where the reviewer states the kit won’t work specifically on the 1998 engine. That’s strange to me and seems incorrect- I have two heads, one is a 7120 of an earlier (1991-1995 I think) and then there’s the 0630 casting that came off my 1998. Both have 5/16 valve stem diameters by my measurement so I don’t believe there’s a difference. I’m assuming the whole problem with valve stem diameter is the earlier years are a different size so the later heads won’t work with the keepers and other valve spring parts that come in the kit. Moses: My assumption, too. We’re in accord here… Keith M.: I’m just trying to avoid getting the wrong cam and having it fitted to the bearings and then having to get another one. I don’t want to reuse the stock cam really, but I don’t know enough to say a different cam is worth it. This Jeep needs to idle and drive well on the street, I can’t have it be stumbly or rough idling as I will be selling it at some point soon. I do want to learn how to do these builds well as I restore IH Scouts- the 4.2 was an available engine that I think is much better in many ways than the IH engines and if I could find a way to build an excellent and reliable stroker with a 4.0 block and the 4.2 crank I’d do these regularly. Moses: Understood, Keith…I’m a Scout buff, too. If fuel efficiency is an aim and vehicle weight not excessive, a 4.6L build from a 1991-99 (pre-C-O-P) 4.0L block and head could make sense as an alternative to the 304 or 345 I-H V-8. I-H was wise to outsource AMC 4.2L/258 engines, they offered a high-torque design that tolerated emission controls better than competitors. Keith M: Thanks for your help Moses, I’ve done my best to sift through all the info out there and I just can’t come to the right conclusion without your advice...Respectfully, Keith M. Moses: No problem…You want to build a safe and reliable engine. My recommendation for the 252H grind has always been simple: This grind offers increased lift with moderate duration. More lift without increased duration means a “bottom-end” camshaft that actually enhances the idle, tip-in response and mid-range power. This cam is much different than the 260H grind. Since the 1980s, I have recommended the CompCams 252H for fuel efficiency, quicker torque rise (more diesel-like), superior idle and rock crawling tip-in stability. This camshaft raises idle vacuum and maintains higher manifold vacuum from idle to mid-range rpm. This is simply a trailer pulling, rock crawling, high manifold vacuum camshaft for optimal power at low speeds, midrange and to a realistic 4500-5000 rpm maximum shift point. It will make power to 5,500 rpm in a pinch. In your 1998-based pre-C-O-P PCM engine, you should experience no problems. The lift is not extreme and will not create valve spring “coil bind” with stock ratio rocker arms. (Valve springs must be new or in good condition and provide the proper spring rates at specified valve spring heights.) With a stroker crankshaft, the 252H makes even more “stump-pulling” sense. The gearing of your Jeep should target a 4500-5000 rpm maximum engine speed. Your single rail EFI/MPI, the 1998 PCM, MAP sensor and camshaft sensor will find this camshaft compatible. The 302 Ford V-8 injectors described in my articles will make sense. C-O-P engine builders should consider the newer grind from CompCams to avoid engine check light issues. The C-O-P PCM and camshaft position sensor monitors the OEM camshaft valve opening/closing events (lobe valve timing). The CompCams 252H valve opening/closing events can trigger an engine check light on a C-O-P engine with its PCM programming. A roller chain (Cloyes or similar) timing set is always an improvement, though the 252H camshaft will work with a stock/OEM replacement set as well. Your focus should be selecting the correct length pushrods and setting the valve timing to factory marks. This is optimal valve timing for the performance gains I have described…Make sure you install the distributor correctly, which will properly index the camshaft position sensor and ignition rotor in the process. There is nothing exotic about the 252H grind. I have installed this camshaft as an OEM replacement. The valve/lobe timing creates an issue with the C-O-P engines because the later PCM is looking for specific valve opening and closing events in relationship to the crankshaft. Let us know how your 4.6L build turns out and your impressions of the 252H camshaft performance... Regards, Moses
  2. I recently ordered you book Jeep cj rebuilder's manual. It is due to arrive June 21. I am putting a 1994 yj 4.0 engine into my 1982 cj8. I did this about 20 yrs ago and used hesco harness. They don’t offer this any more but it looks like I can order one from mopar performance with the same part number p5007148 as the old hesco number. Would you have any idea if they are the same. Any help would be appreciated. Thanks, Bill Himelright
  3. So I picked up a 2004 XJ 4.0 engine and didn't realize the many differences in the block casting from the older 4.0. It wasn't until I started doing more research on the engine that I realized this, but I did get the engine for a really good price that was too good to pass up. Being that I've already put in some time into this engine, I HAVE to make it work. The first issue that I ran into was with the driver's side motor mount pads on the block. on the older 4.2 and 4.0 engine, the top bolt pad is pushed back about half an inch, and on the XJ 4.0 they are flush with each other. So, I went ahead and cut the top one off about 1/2" and that left enough thread for the bolt. There is some space between the mounting plate and the block, but not much, that I am going to use washers. I'm hoping that will work. For the passenger side, I had to do some cutting on the CJ7 motor mount brackets and a bit on the block due to block webbing interference. Now, the next issue that I am facing is with serpentine accessory drive. I wish that I could just use the 4.0 accessories, but being that I did not get the harness and computer with the replacement 4.0, I am going with the carb setup. So I will be using the 4.2 intake. Unfortunately, the water pumps are different. The older 4.0 engines have the built-in power steering bracket on the pump, so it's not like I could go this route to solve my power steering issues. This is starting to be somewhat of a headache because it is turning out to be a much more involved swap than I thought. I wish that I could just go the fuel injection route and be done with these issues. This would allow me to use all 4.0 accessories without an issue.
  4. Hello I am new to the forum. I have a question for Moses Ludel. Moses my uncle and I have rebuilt a 505 performance 4.6L stroker due to the main, rod and cam bearings worn out prematurely. The motor had roughly 12,000 miles on it before I loss oil pressure and upon tear down noticed the bearings were worn out. We have since rebuilt this motor, utilizing a new scat crank with all new bearings and rings. The block was vatted and did not require the cylinders to be oversized but instead a light hone was done. We chose a complete Comp cam kit (68-232-4) we were not able to use the valve springs from this kit due to the retainers not fitting the valve stems correctly. So we used the existing springs that were used with the 505 Performance cam which was the (266/272-14H). We just fired this motor up yesterday for the break in process and the lifters will not prime up and the top end rattles. In addition we seem to have a timing issue (popping at the exhaust above 1800 rpm). I am kind of at a loss on what our issue is. Any help would be appreciated, Mike
  5. Many Jeep owners need how-to information on checking valve clearances and adjusting the hydraulic valve lifters on the inline 232, 258 and 4.0L six-cylinder engines and the 2.5L Jeep pushrod engine. Between the model years 1971 and 2006, Jeep used these AMC-design 232, 258 and 4.0L sixes and the 2.5L straight four-cylinder engine (1983.5-2002). The hydraulic lifter and valvetrain design has particular needs, especially the valve clearances. When these engines develop valvetrain noise, owners often think a valve adjustment will cure the problem. In each of these AMC/Jeep engines, valve clearances are set during assembly of the engine, and adjustment is not necessary between engine rebuilds. If your engine has developed valvetrain noise, or if you are in the process of rebuilding the engine and need to know more about setting valve clearances, my HD video from 4WD Mechanix Video Network at Vimeo will assist. This video was originally a Q&A Vlog at the magazine, now available for a broader viewing audience through Vimeo. Moses
  6. Valvetrain noise and rocker arm interference after cylinder head work can be issues on the AMC design engines. Causes can include sluggish oil flow through the hydraulic lifters, the lifters bleeding down, or possibly excess valve/lifter clearance from valvetrain wear. At 200K miles, that's a very real possibility. Another possibility, since you're certain it's not a lower end bearing noise, is a carbon buildup knock (not likely with an MPI engine) or a piston-to-wall clearance issue. Piston skirt wear is likely, too. It works like this: Pistons naturally expand from heat. There is the normal piston-to-wall clearance to accommodate expansion when new. Over time, the cylinder bore wear creates cylinder "taper" toward the top of the cylinder. The piston skirts also wear. Over time, the cylinders and pistons wear. Cold, the engine was noisy, the pistons expanded, and for a while, anyway, the engine quieted down when warm. Now, the lifters are clacking, the cylinders are worn, the pistons have worn, and you get the sound effects! Another noise can be piston pin wear, which causes a double-knock rap...You would notice this clearly as a dominant sound when the engine is unloaded and you tip the throttle in and out. Use of an automotive stethoscope, a copper tube or a piece of PVC tubing can help isolate engine noise. Be aware that these noises will be transmitted widely and very exaggerated while using these sounding probes! At 200K miles, these engines have done a heroic job tugging a Jeep around. 2.5L models with 4.10:1 axle gears, which make the piston travel extreme over this many miles, wear an engine out sooner. An engine with this kind of mileage needs a suitable burial or rebuild it completely, restoring the short block and cylinder head to OEM specifications with pushrod lengths checked (changed if necessary) for proper valve clearance/lifter preload. Some want to swap an inline 4.0L six in place of the AMC 2.5L four, and that's not easy. I'd consider a smaller V-8 swap (GM LS 5.3L makes sense) as a practical alternative. The Jeep YJ and TJ Wrangler frames are, for unfathomable reasons, designed specifically for either an inline four or a six-cylinder inline engine. (You can see photos of the motor mounts I fabricated during a 4.0L swap into a 2.5L YJ Wrangler, and frankly, it would have been just as easy to install a hybrid V-8.) Granted, the 4.0L radiator, shroud and transmission locations were straightforward, although a four-cylinder YJ/TJ model uses an AX5 transmission, which would be replaced by a 4.0L's AX15 transmission. Aside from fabricating motor mounts, there would be wiring, cooling, exhaust, the AX15 transmission, 4.0L PCM setup and other changes. Moses
  7. Many Jeep owners need how-to information on checking valve clearances and adjusting the hydraulic valve lifters on the inline 232, 258 and 4.0L six-cylinder engines and the 2.5L Jeep pushrod engine. Between the model years 1971 and 2006, Jeep used these AMC-design 232, 258 and 4.0L sixes and the 2.5L straight four-cylinder engine (1983.5-2002). The hydraulic lifter and valvetrain design has particular needs, especially the valve clearances. When these engines develop valvetrain noise, owners often think a valve adjustment will cure the problem. In each of these AMC/Jeep engines, valve clearances are set during assembly of the engine, and adjustment is not necessary between engine rebuilds. If your engine has developed valvetrain noise, or if you are in the process of rebuilding the engine and need to know more about setting valve clearances, my HD video from 4WD Mechanix Video Network at Vimeo will assist. This video was originally a Q&A Vlog at the magazine, now available for a broader viewing audience through Vimeo. Moses
  8. Thanks for the detailed and quick reply Moses, very interesting tech. I think you're right it is probably multiple worn parts making clattering together. I am looking forward to tearing down this engine one day and seeing how it looks/checking the wear. This is Mike at MCE Fenders (MCE Mike on Facebook) and this is the lime green Jeep in our photos. (Also emerald green before it was painted) I've owned this Jeep since I was 16 in 2000. You are absolutely right, this is a testimonial for this engine. I am absolutely amazed at how problem free and durable this engine is. Since it doesn't have much power, and had larger than stock tires on it since ~60,000 miles, this engine spent a lot of time at full throttle and/or high RPM. It has had 31s and 4.10s for a few years, 33s and 4.10s for about 6 months, 33s and 4.88s for a few years, and has been on 35s with 4.88s since 2008. I could also go on about all the times it spent revving high in the snow, breathing dust in the Moab and PNW silt, and it has overheated a few times due to a water pump and electric fan issue. I always just kept the oil changed. I am probably not going to do an engine swap for a while - just not enough time right now and focusing on other Jeeps and the company, but am collecting ideas on what to do. I am definitely leaning towards a small V8. I don't want a huge powerhouse, I rather have reliability of the entire Jeep rather than a HP number on paper. So was thinking a Vortec 4.8 or possibly a 5.3. From the research I have done, the Magnum 5.2 and 5.9 are the "easiest" swaps for my TJ electrically, so those are also on the drawing board. One other idea is to try 505 Performance's new 2.5L stroker kit and head. (2.7 and 2.9 options) But I am still researching this. While the sound and power of a V8 is fun, keeping the light 4 banger but adding power might also be fun. In '08 I swapped the AX-5 for an NV3550 with junkyard parts, and bolted on a NV241-J to that. So I am thinking they will be fine with either option. The front axle is a high pinion 30 out of a Cherokee. This would probably be fine for the stroker 4 cyl. option, but probably need replacing for the V8. This Jeep doesn't have a rear axle at the moment, but it will probably get a D44 when I have time to get to this project. Too many options, haha! Mike
  9. I am trying to find the cause of a rich running engine, and I'm running out of ideas of what to do next. History: Wife bought me and my son this Jeep sight unseen a few months back for us to fix up. 213,000 miles Initial engine problems identified: Heavy exhaust smell, cracked exhaust manifold, Clogged CCV valves with oil bypass in air filter. Overall the jeep runs great other than the strong exhaust smell and bluish smoke from exhaust pipe. No noticeable power difference from other wrangler 4.0s i've driven. Haven't driven it enough to report on gas mileage. Smell is too harsh to drive for long periods of time, especially with top off. Items I have tested or replaced: 1. New CCV valves, gaskets, vacuum lines, air filter - not getting any blow by since 2. New exhaust manifold 3. New NGK O2 Sensor 4. New spark plugs, oil change, oil filter 5. New vacuum line from fuel pressure regulator to intake manifold 6. Compression Test 1:150 2:155 3:160 4:155 5:160 6:160 7. MAP sensor - tested ok 8. Fuel Pressure - 31 psi 9. Fuel pressure regulator - I believe tested ok, disconnected vacuum line and fuel pressure increase 10psi 10. IAT - tested ok, but had blow by residue so ordered new one to replace (not installed) 11. Thermostat - Engine gets up to around 205 per inside gauge and then drops 10deg or so, so thermostat is opening. Heat is working too good for Florida 12. Injectors - Tested resistance in Ohms and they are within range (13.8-14.4), also disconnected each one individually and there was a noticeable reaction from the engine 13. Vacuum Leaks - Have checked and replaced what was cracked. I don't feel there are any leaks. At this point I'm looking for advice on what to do next: My plan: 1. Replace IAT just because I ordered a new one (arrives tomorrow) 2. New Cap and Wires 3. Check/ replace coolant temp sensors (both) 4. Probably needs a new CAT, but wanted to get the rich running under control before replacement. Maybe the old cat is non functioning and is the cause of this? I don't feel that this is the cause, but not enough experience to know for sure. 5. Replace injectors?? Maybe a bad spray pattern...clog??? Thank you in advance for any guidance!
  10. There has been a long thread of exchanges at Timmy960's topic on harsh shifting after rebuilding an AX15 transmission. The problem around 3rd/4th gear shift issues has a basis in the redesign of the synchronizer sleeve, bronze blocking rings and the third gear cog teeth for the sleeve engagement. Jason Logan and I had an exchange about this issue when he rebuilt his '99 TJ Wrangler unit. That exchange was just prior to the launch of the forums. For the benefit of all AX15 rebuilders, I am starting a new topic around this issue, beginning with the in-depth Q&A exchange that Jason Logan and I had...Since this exchange, Jason, Gary, Tim and I have been using the new forums to disseminate AX15 transmission rebuilding details...Here is the original exchange with Jason. I have highlighted important facts: Jason: Hello Moses! I have recently taken advantage of your detailed instruction on how to rebuild an AX15 manual transmission. I am currently working on an AX15 manual transmission from a 1999 jeep tj 4.0L that has never been rebuilt. I have a question regarding the stock 3rd and 4th synchro ring and the corresponding slider [sleeve]! The stock slider has an angle cut on one side and a straight cut on the other side. Also, the stock 3rd gear synchronizer is angle cut and the 4th synchronizer is straight cut. (I may have these backwards). Why is it that the dealer and aftermarket only show that both 3rd and 4th synchronizers are identical (either both are an angle cut or both are a straight cut). I ordered a 3rd and 4th synchronizer from Chrysler and they are identical (straight cut), and when I ordered a set from the aftermarket, the 3rd and 4th were also identical but with an angle cut! Should I use the Chrysler synchronizers (both straight cut), the aftermarket (both angle cut) or should I use one of each to replicate the stock setup as described above? I have put this rebuild on hold for weeks now trying to get some answers from many sources but nothing has been rock solid. I was hoping you could help me and give me some clarification on what is the best set up and why? Why does the slider [sleeve] have different cuts? Why do the replacement synchros have different cuts, different part numbers and configuration of teeth? Thanks for any information you can give me. Jason Logan These photos courtesy of Jason Logan ("JayDLogan"), forum member...Note the 3rd/4th gear sleeve and cog design for his 1999 TJ Wrangler AX15 transmission. Click on each photo to enlarge image. Moses: Jason, I would match synchronizers precisely to the originals and in their original locations. Measure the diameters of the rings, their angles and, most importantly, their fit against the synchronizer hubs in their correct positions. Make sure you face the synchronizer sleeve in the correct direction. Start with the original rings in correct relationship to the synchro hubs and sleeves. Note the overall “width” of the synchronizer assemblies, and then compare this with the aftermarket (new) synchros from both generic and Chrysler sources. The goal is to have synchro rings that will behave and fit just like the originals. Wear on the OEM rings is typically slight, perhaps a few thousandths, so you will know immediately if the parts are either wrong or in the wrong locations. AX15 synchro rings are not the same diameter, and the difference is slight, often confusing the assembly. My article provides details on the kind of “fit” and end plays you should achieve during assembly. Take your time, Jason, you’re already ahead of the game by questioning the parts to make sure of their fit and placement. The OEM layout and fit is your template. Match this and you will “restore” that AX15! Trust this helps…I’ll be at Moab through Thursday and out of communication. Let me know your findings in an Email. I will answer next Friday…Best of luck, I know you will do the right thing here… Moses Jason: Thank you very much for all of your information and help - my dilemma is - when I have ordered the synchro rings from Chrysler (they sent me 2 identical 'straight cut' synchro rings) and when i ordered from the aftermarket (they have sent me 2 identical 'angle cut' rings) but my original synchro rings have 'one of each' cut (one ring is a straight cut and the other ring is an angle cut). Although all synchro rings ordered are the same diameter, angles and fitment as my originals, I'm not sure if I should be using what Chrysler sent me (the 2 straight cut rings) or what the Aftermarket sent me (2 angle cut rings) - or should I be using one of each cut to match identically up to the original set up? I would have thought Chrysler would have sent me one of each (angle and straight cut synchro ring) based on the fact that my original rings are 'one of each' cut. And my second dilemma is - the number of teeth and location of the teeth on each ring ordered are not set up identically to my original configuration of teeth on my original rings - does that matter? I'm extremely grateful for your reply and value your expertise. Jason Logan Jason added these parts details: I found some other information, Moses! If you look at earlier years of the Jeep Wrangler 1997-1998 they have used part number 4897051AA (for both 3 & 4 synchro) or 4897052AA (for both 3&4) depending on the month the jeep was made. Part number 4897051AA is a synchro ring that has teeth that are angle cut and part number 4897052AA has teeth that are straight cut (shaped like a house). The jeep I am working on is a 1999 that calls for part number 4897052AA for both 3 and 4. It looks like at the factory, they have put part number 4897052AA for synchro 4 (near the input shaft) and 4897051AA for synchro 3 (near third gear). Very confusing! I also found, like I noted before in my second email, that the teeth of part number 4897052AA and 4897051AA are in a different configuration around the ring slightly than the originals as you can see in the pictures. I have purchased many 3 and 4 synchro rings but none of the teeth patterns match up! I had no problems matching up 1,2 and 5 synchros. I hope this helps you understand what I am up against! Thanks again! Jason Logan P.S I purchased part number 4897051AA today from Chrysler to clarify if it was angle cut and indeed it was! Moses: Hi, Jason, I’m just back from Moab, UT Jeep Safari…You sent great photos, this is all very interesting! Since the gear/ring in question is really 3rd gear, my belief is that Chrysler/Aisin discovered downshifting to 3rd problems and implemented a remedy. The angle cut would engage the shift sleeve differently, apparently allowing easier engagement on the downshift from 4th to 3rd. It would seem like either ring would work, as they each engage the sleeve troughs accurately (taking a straight-on view). The difference is that the angled ring would engage the sleeve with a different pressure and slight rotation of the ring. Just a guess, but this seems the only identifiable issue. Think about the third gear engagement: Shifting up, there is the lag in the shifter’s neutral gate and a “slower” engagement of 3rd gear. Shifting down, however, would be a direct, quick movement of the shift level and fork. Consequently, the sleeve would want to quickly rush over the brass ring teeth—without providing smooth or effective braking action at the gear hub. This would cause harsher gear engagement. Apparently, the slight angle makes the downshift to 3rd gear smoother, with better braking action and less risk of gear clash. Probably, either design would work if all drivers shifted up and down smoothly and without taxing the synchros. However, American drivers (and others with Jeep vehicles) want to affect a quick downshift to 3rd gear. The concern here, though, is to match the bronze rings with the updated synchronizer sleeve design. Does this make sense, considering the parts layout? The tooth spacing and offset on the rings has more to do with keeping the ring as close to square as it moves onto the gear hub. If nothing else, this is a testimonial to the precision design of Aisin transmissions, more like Euro types than U.S. gear products. The aim with a wedge ramp instead of arrow teeth is the shift “timing”, and that’s a precise consideration. This reflects the rest of the AX15 design quality and fitment. These are more complex units for a reason. I’m sure your build will be stellar, Jason! Let me know how this turns out. Regards, Moses Jason: Makes perfect sense Moses! Would it make sense to you to use the angle cut synchros for both sides of the slider even though the slider on one side is straight cut and the other is angle cut? I am still unsure if I should use both angle cut synchros, both straight cut synchros, or use one of each. The rebuild kit I purchased had two angle cut synchros, I am wondering if this is the upgrade? To me it is like rolling the dice on this decision! Thanks for all your input. Very much appreciated. Regards, Jason Photos courtesy of forum member Jason Logan...Note the OEM synchronizer design for this late version of the AX15—Mopar parts. Moses: I would follow the OEM approach if you’re sure the transmission is original, never before apart (which you believed from the start). The model year is late enough in the game for the synchro "solutions" to be in place…I would match the bronze rings and synchro sleeve carefully to the OEM layout. If this transmission shifted well for all of those miles, I would take this approach! As a final check, place the new synchro rings against the gear hubs to be sure the fit is aligned. You can put a light film of grease on the ring contact surface to read the fit. Wipe the grease away before assembly and coat the ring with a thin film of gear lube. Let me know how this all turns out, Jason… Best, Moses Jason: Thanks again Moses! I hope you had a successful trip to Moab, UT Jeep Safari. I have wanted to go for many years. Wish me luck on the AX15! Regards Jason Moses: Hi, Jason…Moab is breathtaking scenery, with contrast ranging from sandstone/slick rock to alpine peaks capped with snow this time of year, the Colorado River, arches and formations, all of it! I trust you’ll make it at some point, and if so, let me know. I do make the Moab Jeep Safari each year…Like Canada, we live at a “winter zone”, 4400 feet elevation near Reno. We look forward to winter’s end, and Moab Jeep Safari has become our annual end of winter/early spring gathering! You’re going to do a great job on this AX15! Follow the assembly steps faithfully, there are no shortcuts. When completed, you’ll have a smooth-shifting unit, as new, and that will be very gratifying! Let me know the outcome… I launched a message board today with a large number of forums at www.4WDmechanix.com/forums. It would be great to see your involvement if you have the time. Tech forums need detail-oriented members! It’s new, and I’d value your feedback about the forums you find interesting, the sign-up procedure, member validation and use. Best, Moses Note...Jason and I moved this conversation to the new forums at this point...When rebuilding an AX15 that has never been rebuilt before, lay out the parts as you take the unit apart, identify the synchronizer design for 3rd/4th gear, and match parts to the original design. There is a distinct difference between "earlier" AX15 and "late" AX15. The rebuild core in my magazine article and the A150 (Toyota version of the AX15) depicted at the Weber State University YouTube video (click for post topic threads containing the embedded video) are 1990-92 "early" AX15 design. Later model Jeep vehicles with the AX15 use a redesigned 3rd/4th synchronizer assembly...Rebuild accordingly, matching and using the right parts! Jason has added charts from an Aisin direct dealer that show the synchronizer applications for 1998-99 AX15 transmissions. Make sure you check your synchronizer rings and the synchro sleeve design for 3rd/4th gear. Install matching rings for your transmission. Be certain to install the synchro sleeve in the correct direction! ("House" or arrow shaped points match the 4th gear ring with house or arrow point teeth.) Here is an approximate application list with Aisin part numbers (not Jeep/Mopar): Click on image to enlarge...Thanks to Jason Logan for the chart!
  11. Hey I was looking to upgrade my 1998 Jeep Cherokee SE’s ignition system. My intent is to drop the distributor and replace it with a camshaft synchronizer (https://www.morris4x4center.com/dorman-camshaft-synchronizer-oil-pump-drive-includes-sensor-dor-689200.html?gclid=Cj0KCQjwn7j2BRDrARIsAHJkxmw1PJPPvcy8YpgleZmsRNOW_q9zw78_4IXXuvfIbh7uufSEW3rMaaEaAtSzEALw_wcB) , and a RIPP 3.8 High Performance Coil Pack (https://rippmods.com/collections/jeep-wrangler/products/ripp-3-8-high-performance-coil-pack). “Viper Coil Kit” Will this work with my current wiring harness and PCM? or will I have to grab a 99-01 wiring harness and PCM to make this work?
  12. Moses, I have watched your videos regarding how to approach a stroker motor. I have read tons of info on the internet, and I've seen many calculators for quench height, combustion cylinder volume, etc. It really is baffling to me, and I've begun to realize I could invest a lot of money and end up with an engine that doesn't work. Is there any identifying info on the block that would allow you (or someone) to write me a "recipe" for what parts I need to build up a stroker? I'm realizing that the added weight of the full size truck axles and 38" tires are going to necessitate more power. I've been thinking about Ford 302 power, as I have secured a 1993 EEC IV harness and computer, but that swap has its own challenges. I always thought a stroker was the best way to spice up my powertrain, and I still like the idea if I can be relatively certain if what parts I need to buy to get it right the first time. Please let me know what you think.
  13. New here and tried searching but came up with nothing similar. My 06 LJ 4.0 (155000 miles) recently developed a habit of going to a fast idle/high rev of around 1500 RPM's or so. If I blip the throttle it settles down until you take of again and it repeats. I installed a Genright 31.5 gallon fuel tank and replaced the fuel pump assembly at the same time because it was a whole lot easier and I didn't want to drop the new tank anytime soon. I had a code for EVAP system small leak which I attributed to the vent hose from the tank to the filler neck as the hose that came with the tank was rather short and had no clamps. I installed it and put some zip ties on it until I could get a new section of line and clamp, which I did a week or so later. I also had a code for O2 sensor which I forgot to write down but it was present long before these symptoms began. I have searched for vacuum leaks but it's possible I might have missed one. Anyone have thoughts on this?
  14. Hello, I have some trouble with mpgs, idling and acceleration on my Wrangler YJ 1995. 4.0. Recently went to a mechanic, he connected my PCM to a DRBIII scantool, and he told me that the adaptive factor is -80%. He did reset all adaptive memory, and I can feel improvement in mpg and acceleration. Is there any way to reset adaptive memory other than connecting it to a scantool? I've read on internet about touching positive and negative cables (or grounding postitve), that it empties the capacitors in PCM adaptive memory. The reason I'm asking this is because I don't have scantool available all the time, and that this error is due to a bad LPG map (I have converted this JEEP to propane).. So I would like to once again reset memory, and after PCM relearns to copy that map to a LPG controller so there would not be any differences.
  15. I am working on a 2002 Wrangler 4.0 automatic. I found this connected grounded to the left side of the block. I have no idea what it is or what it does. Any help would be greatly appreciated. Thanks so much, Jake
  16. I have a 1997 Jeep TJ Wrangler 4.0 with 171K miles on the clock. This mechanic at work is making me very nervous telling me that the oil pump on the 4.0L takes a dump between 150 and 200 thou miles and I should be aware of this..Im a worrier and he's got me going now. Anybody have any input on this and what I should do? the engine runs great. When I start it cold it has 50 lbs oil pressure. when its warmed up its 40 while driving and 20 sitting at a light. Sounds normal to me but have any of you had issues with the oil pump? He says when it goes its too late..New motor time..
  17. Going to swap my old 258 w/ 4.0 head for a 99 model 4.0 in my 84 CJ-8. Already have the mpfi setup, just going to use it along with the TF999 trans. Question is will the flexplate and starter both work on the 99 4.0 engine? I've been told that I need the flexplate that fits the engine and to drill it to fit the trans. torque converter. Just need to know which is correct. Thanks
  18. I have attached a few pictures of this transmission I have but I don't know where its from I need help identifying this transmission the only thing I can identify here is the transfer case because it has the sticker in the back its an NP "new process" 249 J This is a manual 4wd transmission I believe its an ax15 transmission but please give me your input as i'm not sure any help is appreciated one more thing from the shape of the bell housing I don't think this came of a Jeep possibly AMC or other but thanks again
  19. random, intermittent #1 cylinder misfire. I have replaced the coil-pac, #1 injector, spark plugs, and both upstream O2 sensors. engine leakdown and compression normal though #1 slightly lower in compression. emissions always meet I/M standards (no certificate of waiver needed). have all heat shields including #3 injector so vapor lock not issue. engine runs good when not misfiring though does have a slight roughness noticeable when at idle. Is there any way to check the current of an injector wire or plug while engine is running and showing symptoms to see if all is well in the wiring harness? engine bay is quite clean for 235k mi. and no noticeable damage to wiring harness, but there could be a partial open in a circuit I suppose. Any ideas? don't know where to go from here with repairs/diagnosis etc. Oh, misfire occurs mostly after engine has been under normal-use-load for a couple hours or so, but not always. sometimes it is misfiring at cold-start.
  20. Greetings from Northern Michigan, I am in the process of building a stroker for a 2002 TJ. I need to check the pushrod length. The engine is still on the stand. Do I need to prime the lifters to get the proper pre-load? Thanks so much, Jake
  21. The weather has warmed, and we're not using the block heaters. (They provide approximately 140-degrees F coolant temperature at start-up.) When starting the Jeep XJ Cherokee's 4.0L engine on a relatively cold morning this week, I could hear a subtle misfire. This was during the warm-up/enrichment cycle, and by the time the engine came off the warm-up cycle (around 140-degrees F), the idle stabilized. At highway speeds, the engine seemed to run smoothly in terms of cylinder firing, though there had developed an unusual downshifting habit on grades and strong headwinds. Concerns came up about the TPS or oxygen sensor, maybe even a fuel supply issue. Miles earlier, however, the TPS had been replaced, and the O2 sensor as well. Giving this some thought, I pulled the air filter out. Holding it to sunlight, there was little light showing! The filter was neatly and uniformly clogged. This was the burbling at idle and sluggish on-highway at cruise trouble spot. So why didn't I replace the filter earlier? I change oil and the oil filter on cue, watching the oil color constantly. The air filter, however, gets dismissed when our mileage is mostly highway without dust conditions. In looking at the clogged filter, it was clear that winter "road film" was the culprit, and this can be just as impacting as dust and dirt particles. How did the engine continue to run in this state? Because the marvel of modern EFI has the O2 sensor compensating for air/fuel ratio constantly. Unlike a carbureted engine, which would show symptoms of an over-rich running condition much like running with the choke on, the A/F remains normal with EFI. At highway cruise, especially with an engine that chugs along at only 2,000-2,100 rpm most of the time, there is limited CFM (cubic feet per minute) air flow needed to maintain the A/F at that throttle setting. However, when load demands raise the throttle opening and drop the manifold vacuum at the same time, notably with the cruise control operating, the engine requires a transmission (AW4 in this case) downshift to maintain the A/F ratio constant. This creates the needed power at the expense of fuel efficiency. The dirty filter explained the downshifting on hills and subtle misfire at cold idle during the enrichment cycle. The moral: Check your air filter regardless of the season and whether or not you're driving off-pavement. Of course, when driving off pavement, one trip down a desert alkaline road can clog a brand new air filter. On highway, this does take longer, but with winter road debris and salted roads, the dirt accumulation is equally impacting. It just takes a bit longer to produce symptoms. A good rule-of-thumb for replacing the filter is the factory service interval. In our Jeep 4.0L engine's case, I'm targeting every 3rd or 4th oil change when driving strictly on-highway. For dusty off-pavement conditions, inspect the filter regularly and replace it as soon as necessary. Moses
  22. Im looking at building a motor for my 83 Cj7 I have options, I have a 96 4.0 parts motor with 0630 head plus a spare 7180 head. I have two 258s one is a 1990 (006CL25 / EF3235444) the other an 80 (009C09 / 3235444). The 1990 258 i could just re-ring and drop a 4.0 head on, i wouldn't even have to plug the water jacket holes in the head as the 90 block is squared of on that side like a 4.0 block, re cam with a RV unit and i'm hauling like never before. Pretty strait forward. Or; Take the crank and rods from the 1980 block and put them in the 4.0 block. With this one i would keep the 4.0 pistons, install new rings and because the 1980 crank is the last of the 8 counter weight heavy cranks i would assemble it and assume im pretty close on balance and see what it runs like. Im thinking the second one is a bit of a gamble on the balancing but i've put lighter pistons in small block chevs before and never had to rebalance, so ive been there done that. Anybody out there done a heavy crank to 4.0 swap with all stock stuff? think it could work?
  23. Ok, here is my situation. i am new to the the jeep owners world. I have wanted a cj since I was 13 yrs old and I finally got one about 2 months ago. I bought an 85 cj7, it has a 2.5 l 4 cyl with a t4 transmission. I bought it with the expectation of putting in a different motor and trans, however, what I did not count on was how much body work I would end up having to do. The body work has taken a huge chunk out of my budget for the motor. A buddy of mine gave me a 4.0 out of his 88 comanche. the engine ran but had been sitting for 7 yrs and all of the seals leaked, including the main seal. My original plan was to use this motor and carburate it since I don't have all of the parts for the fuel injection and I want to keep it as simple under the hood as possible. My question is, would this be possible and could i use the existing motor mounts. Also, what else would I have to do to make this work? Any help on this would be greatly appreciated. Thanks
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