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My Jeepster has the 225/3 spd and everything works quite well. However, to modernize it a bit and make it easier to drive for my wife, I scrounged up a 1984 Cutlass with a 3.8, and a 700R4/208. I also have (still on the truck) a 1991 Chevy 350 with TBI. My plan is to rebuild the 3.8 with buick 3.0 pistons and the Melling MTB1 cam. Add the TBI for easy starts and efficiency. The 700R4 is for my wifes bad knees. Any suggestions?

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This is not a bad path.  The 700R4 would need to be from a 4x4 truck or adapted with an Advance Adapters kit to the Jeepster's Dana/Spicer 20 transfer case.  You mention the NP208.  Be aware of the drop side (right or left) to the front axle.  The Jeepster uses a Dana/Spicer 20 transfer case that drops to the right side at the front axle.  An NP208 drops to the left side.  The transfer case's front drop side must match the front axle's differential location.

I'm not clear whether you're rebuilding the Buick 3.8L V-6 from the '84 Cutlass?  You describe the pistons as "3.0".  Do you mean 0.030" oversized for a 231 Buick V-6?  

The TBI could work if you have the ECM and all of the sensors.  Many swap the entire 350 V-8 into a Jeepster.  Does the Jeepster have manual steering?  A GM/Saginaw rotary valve integral power steering gear is a popular conversion for these vehicles.  I have used the slower ratio GM "big car" (4-turns lock-to-lock) steering gears for this kind of application.

Advance Adapters makes adapters for mating the 700R4 to the Jeepster transfer case.  Most use the 700R4 overdrive (4-speed) transmission or a 3-speed THM350 or 400.  The Jeepsters of that era actually used a THM400 3-speed automatic behind the 225 (Buick) Dauntless V-6.  This was exceptionally strong for the vehicle's size, weight and engine output.  GM 4x4 pickups of that period got the lighter duty THM350.  The 700R4 would have the advantage of overdrive.

Anyway, I would like to know more about the parts you're considering:  the engine, transmission, transfer case and induction system.  If you do run a 231/3.8L Buick V-6, I would use a TBI system from a 4.3L Chevy V-6.  Howell (https://howellefi.com/) makes a wiring harness and other parts for GM TBI conversions.  You would need an ECM and all related sensors.  The Chevy 350 TBI V-8 with all of its sensors and ECM might be an easier swap if you want TBI.  Advance Adapters has motor mount brackets and other swap parts.  You would need exhaust system, cooling system, wiring harness and fuel supply system pieces suited for EFI/TBI and a larger output engine.

 

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  • Moses Ludel changed the title to 1971 Jeepster Commando 231 V-6 and 700R4 Swap

The 700r4 is from a 86 chevy pickup, and the 208 is passenger drop. There were a couple of years when they did this on solid front axle trucks. I thought about adapting the Model 20, but thats another adapter to buy. Good case, I know, but the 208 has a lower low, and the weight of the Jeepster is quite a bit lighter than the truck it came out of, so I'm not worried. SO it'd just be a BOP to GM adapter ring and the flex plate thats native on the 3.8 (I think, havent found out yet if it will work, but its a 3 spd 200r in the cutlass.) Jeepsters are really rare in SE Wyoming, so I'll probably have to fab the crossmember.

I had also considered using the 350 that is in the other parts truck, but that opens up a lot more fab stuff that I don't want to do anymore. (three spine surgeries makes it rough sometimes) It is a running truck, so all of the sensors and whatnot are there. But I think you're right on the TB, it might be too large for the 3.8. I thought it was just the injectors that changed between the 350 and the 4.3? Not sure.

The 3.8 needs a rebuild, hence the idea of bumping the compression to 10:1 with buick 3.0 pistons. They're flat tops like with the 225, and the same bore and pins. I haven't run the Melling cam, but heard it was a good one for the most low end TQ. I noticed that you're fond of the 252 cam. I'll have to look at the specs on that. And if I can ever find a reasonably priced 4bbl manifold for the 3.8, I'll go with that too. Stock exhaust manifolds and a single 2 3/4" pipe. Now if I can figure out if the Electronic Spark Control of the Cutlass will integrate with the later TBI...hope that puts it together better! 

Awesome sight Moses! Thank you for your time! (and knowledge)

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Oh, the steering...picked up an open knuckle Dana 30 with 3.73's (matches my Jeepster), and a power steering gear from the Jeepster Guru (Russell Wiktop). I have a disc brake conversion ready to go on it and a brake booster and master. Just need a proportioning valve at this point and new U joints. (winter preps on everything got in the way of finishing that part). I actually picked up the entire Cutlass just for the power steering pump and brackets. The guy was very generous and wanted me to haul it off. Its actually in excellent shape body wise and would make a great hotrod if somebody wanted it for a LS swap. But I'm not that guy.

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Mike M...Well thought out and researched approach.  Yes, the Model 20 is noted for its taller low range ratio (2:1), though there are aftermarket gear reduction kits available for a lower geared low range.  If the passenger drop 208 will work, it's much less expensive, and the 208 chain drive TC is plenty strong for this application...You've thought out the solution of a BOP to Chevrolet adapter ring, be sure that the stack height (crankshaft/flexplate location, transmission input shaft depth and converter fit) is correct. 

Yes, the Cutlass has a TH-200-4R.  Fab'ing the crossmember for the 700R-4 should not be difficult, I usually build-in a better skid plate at the same time.  If you need wiring for 700R-4 kickdown, etc., Painless has a popular kit with harness for these swaps.  Also, if the '86 700R-4 has never been rebuilt, there are some recommended upgrades.  Before the late eighties (1988-89), the 700R-4 underwent several changes, including a front pump seal fix to prevent the seal from popping loose.  Your unit may have these upgrades already.  Others impact the longevity of the unit.

Howell would be a good resource for confirming injector size compatibility between the 350/5.7L and the 4.3L V-6.  If the 4.3L injector is the only difference, and if it's a direct fit to the 350 throttle body, that would be simple enough.  (You could source a 4.3L replacement injector.)  Your will need a V-6 ECM and wiring harness, and the 4.3L could be a source.  Unlike multi-port/sequential fuel injection, throttle body injection would not create a problem as far as the cylinder firing order goes.  It simply needs to know the #1 cylinder TDC reference.  Regardless, both the Buick 3.8L and Chevy 4.3L use a 1-6-5-4-3-2 firing order.  (Confirm cylinder bank numbering.)...You will need to sort out the distributor/ECM interface, and this could be an issue.  If the ESC distributor won't work as a trigger, there are crankshaft trigger/sensors available from Edelbrock, Holley, MSD and others, though that's another cost.  You do need a crankshaft reference signal for TDC on #1 cylinder.

Confirm that the 350 V-8 sensors and wiring are compatible with a 4.3L wiring harness and ECM.  Howell does make a standalone 4.3L wiring harness, you'll need to confirm cost and such.  Harnesses can get spendy.

Ah, you did mean 3.0L pistons with this purpose in mind.  I like the later 231 for its even fire crankshaft and reliability.  The Cutlass 3.8L is the right source, it's rear wheel drive configuration.  10:1 may require higher octane fuel unless the knock sensor can offset the compression boost.  I build these engines at 8.7:1 to 9:1 maximum, which enables use of lower octane unleaded fuel.  Any camshaft choice should target low end torque and mid-range power.  4,500-5,000 rpm would be the maximum rpm you'll ever need, especially with overdrive.  Yes, my traditional choice was CompCams' 252H grind, which is now obsolete for many applications.  CompCams has re-profiled niche camshafts for bottom end power.  My goal in any case is more valve lift than stock with mild duration, a camshaft that produces high manifold vacuum at idle and lower rpm.

The 252 V-6 version of the Buick V-6 was available with a four-barrel (spread bore) manifold.  That's an OEM solution.  Otherwise, you'll be seeking an aftermarket performance alternative.  Be sure to use a dual-plane manifold.  The ESC distributor and ECM compatibility should be explored.  GM TBI functions from a combined fuel-and-spark management ECM.  Again, Howell may have insight into this ESC distributor.  (You'll keep the Howell tech line busy.)  Let us know how this sorts out.

I like your approach with the power steering and disc brake conversion.  Open knuckle is the only way to go from both a service standpoint and turning radius.  You'll have improved steering geometry, too, a smart approach. 

An OEM proportioning valve would be my approach, I've used aftermarket manual valves, they essentially damp down the rear brake apply pressure and lack the ability to apply front brakes slightly ahead of the rear.  An OEM combination valve could also signal a front or rear hydraulic system failure with a light installed at the dash.  Use an OEM combination valve for a vehicle with similar weight, wheelbase length and disc front/drum rear or a four-wheel disc brake system—whichever you decide to run.  Disc front/drum rear is easier on your budget and works fine.  Water fording does require warming up/drying the rear brakes after a stream crossing.  This can be done by dragging your E-brake briefly at a slow speed.

Again, you've done your homework and will do a thorough job.  Please share photos, this sounds like a clean swap and build of a classic and popular Jeep 4x4!

Moses 

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Just going over all of this...not sure which swap would be easier to do. Just spoke to the mechanic that worked the heads and installed an RV cam in the 225 thats currently in the rig. He states that he thinks that the valve seats were replaced at some point. Which of course means that I could run unleaded fuel without worrying about seat issues. Dangit, I thought I had a plan. I would love to run FI of some sort, and an OD trans. Looks like I could use the 225 (48k miles) and not worry about the rest of it. Maybe pull the 3.8 and save it in the corner for future use. Heck, maybe pull both engines. Ive got 3 acres, why not?

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Mike M...It's a 3-5% drop in horsepower per 1000 feet of elevation.  We live at 4,400 feet elevation, so I know your concern.  The good news is that lower octane fuel works just fine for us. 

I found what seems a reliable table for compression correction by altitude.  This is actually addressing cylinder pressure (PSI) rather than actual compression ratio.  (There is static and dynamic compression to consider as well.)  At 5,000 feet elevation, according to the table, you use a 0.862 factor to determine equivalent cylinder pressure.  If this approximates a compression ratio change, 10:1 x .862 equals 8.62:1. 

So, if you drive solely in your altitude zone, you could use 10:1 pistons on the 231 V-6.  I have traditionally used United Engine's Keith Black or Silv-O-Lite hypereutectic pistons.  Silv-O-Lite replacement pistons work just fine, Keith Black for high performance use.  At 10:1, you may need to fiddle with octane, though many GM TBI systems use a knock sensor that compensates sufficiently.  (The 1991 Chevy 350 engine may or may not use an ESC equivalent with knock sensor, you need to check whether it has the knock sensor.)  Here's the table, courtesy of www.TW200forum.com:

Altitude
(ft)
Correction
Factor
 
Altitude
(ft)
Correction
Factor
500
.987
 
3500
.907
1000
.971
 
4000
.888
1500
.960
 
4500
.880
2000
.943
 
5000
.862
2500
.933
 
5500
.853
3000
.915
 
6000
.836

 

Sounds like you're in a holding pattern with a 225 odd-fire V-6 that should last quite a while—especially with hard steel replacement exhaust valve seats.  Will you just keep the 3-speed manual transmission to ease the process?  The Jeepster was optioned with the THM400 behind the 225 V6.  Or you could adapt a 700R-4 (your BOP adapter or the OEM Jeep approach) to the Spicer 20 transfer case.  Length of the transmission would determine whether driveline resizing is necessary.  The torque converter and flexplate would need to match up and fit.  Your Jeepster parts source may have the goods for this automatic conversion.  THM400 to Spicer 20 was common with late Kaiser and earlier AMC/Jeep era vehicles.

Moses

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What about this thought...say I find an 86-88 FWD 3.8  and grab all of the SFI stuff and use that on my 84 engine? That way, its all OEM and designed specifically for that engine. No real conversion work at all, and I end up with a nice, reliable and somewhat economical rig. I havent seen this done anywhere on the net. Have you seen it done this way?

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You'd need to break down the difference between the FWD and RWD versions of the 3.8L.  The SFI idea is sensible, a donor vehicle could even include the wiring harness if you like to sort through schematics and mate harnesses.  Many do this.  I recommend rosin core solder splices with double heat shrink tubing.  Butt crimp connectors are wholly unacceptable for electronic circuit wiring.

For openers, the FWD 3.8L intake faces the wrong way and cannot be "turned around".  An alleged workaround is a '96-2002 Camaro/Firebird 3.8L ("3800) intake.  You'd need to verify the fit.  There are block mount concerns.  I would research the block castings to see if that's an issue.  You would be fabricating engine mounts, but they still need to be at reasonable points on the block casting.  Verify the crankshaft configuration at the front/drive accessories end and the rear flange for the flexplate.  How will drive accessories fit?  Water pump?  Is the bellhousing pattern the same?  Would the Camaro/Firebird 3800 version be a more sensible engine for a swap?  Confirm this.

A good place to research is the long block offerings from engine rebuilders.  See whether a RWD 3.8L and a FWD 3.8L core is the same as a long block part number.  If the basic engine can be used in a RWD vehicle, the notion is sensible.  Otherwise, I'd look into the Camaro/Firebird V-6 3.8L.

Footnote:  I did a further search, and the GM 3.8L "3800" engine may be popular and relatively common.  There are numerous RWD later 3.8L V-6 applications that would have EFI or SFI.  Verify the bellhousing patterns and their fit to a 700R-4.  For a 4x4 application, the 700R-4's output shaft and tailhousing could be borrowed from your truck application of the 700R-4...You may have started a new swap engine trend.  According to one source, interchange is as follows on these RWD applications, and the common part number is supposed to be GM 89017861.  These donor cars should be abundant:

89017861 - 3.8L (L36-K) 1995-1996 Olds Ninety-Eight, 1995-1999 Buick Park Ave, 1995-2002 Chevy Camaro & Pontiac Firebird, 1995-1997 Buick Riviera, 1995-1999 Pontiac Bonneville, Olds Eighty-Eight, 1996-1999 Buick Lesabre, 1996-2004 Buick Regal & Century, 1997-2004 Pontiac Grand Prix, 1998-1999 Olds Cutlass Supreme, 1998-2005 Chevy Monte Carlo & Impala

Drill down on this prospect and see whether there is potential here.  The challenge would be the electronic interface and powertrain electrical wiring.  You need the donor car's engine and transmission wiring harness(s) and a detailed schematic for this one.  Let us know your findings and plans!

Moses

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OK, after having found a donor rig and thoroughly researched this SFI swap....it looks like it won't be a "cheap" junkyard swap. The biggest problem is the intake manifold. the TB is on one end, (the back side when turned longitudinally) and the water neck is on the other. No easy way to use it unless there is a lot of custom aluminum fabrication on the manifold. So that leaves the only other SFI platforms which were Grand National turbo setups. And as you may know are rare and expensive. So, unless you're willing to cut a hole in your firewall and run the air filter in your dash, this won't work. Haven't looked at drilling a standard carb manifold for injectors yet, but that might be an option. So, when it all comes down to the bottom of the pro/con list, the Holley sniper looks like the best option. The Dauntless I have currently runs well, a bit of valve train noise, but still tight and stout. Looks like the Holley Sniper is the proper route, considering I can rebuild the 84 core with the cam/pistons I want and the Sniper will convert over seamlessly. I've turned over every rock I could find, so unless someone has some secret knowledge, this is it.

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I found an 86 Buick Century as a donor (has RWD mount bosses as well as FWD mounts. You'd need the entire engine as there is a requirement for a cam and crank sensor)....the 89 up series 1 3800's have the 60 degree bellhousing. I have the 700r4 from an 86 chevy pickup. Yes, the tailhousing would convert to a 60 deg trans body, but I want to use the trans I have, and not spend more cash on the rare 60 deg variant. The newer 3800 variants would be an awesome swap if a fella hadnt already spent the coin on a 90deg trans. Does all of that make sense?

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Mike M...I had mentioned the FWD engine design issues (intake position, etc.) in my last reply...According to the third link below, the late Buick engines do use a 60-degree (2.8L to 3.4L Chevrolet design) bellhousing pattern.  This would necessitate a different 700R-4 or a 200R-4.  A 2.8L/3.1L GM S-truck might be a source for a transmission.  Here are details on each engine, the 60-degree V-6 and the 231/3.8L V-6—plus the late series 3800:

https://en.wikipedia.org/wiki/General_Motors_60°_V6_engine

https://en.wikipedia.org/wiki/Buick_V6_engine

https://en.wikipedia.org/wiki/List_of_GM_bellhousing_patterns

If the 700R-4 is a deal breaker and "must keep", you'd be back to the older RWD 3.8L cars with SFI.  Rear wheel drive applications with the Buick (BOP) bellhousing pattern would work.  The 1986 Buick Century sounds like a possibility with your adapter ring to mate the Chevrolet 700R-4 to a Buick 3.8L V-6 block (BOP pattern).  Again, verify stack height if you use the adapter ring and 700R-4 transmission.

Moses

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