1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Gm 4.3 V6 In ‘72 Cj5?

Discussion in 'Intermediate CJ-5/6/7/8' started by Jon B., May 17, 2022.

  1. May 17, 2022
    Jon B.

    Jon B. New Member

    SW Minnesota
    Joined:
    Apr 6, 2022
    Messages:
    27
    I tried the search function; no joy.

    In the interest of saving room, I’m considering swapping the busted AMC 304 for a Chevy 4.3L V6.

    A GM swap needs either an adapter between the bell housing and transmission or between the transmission and t-case, so a shorter engine may help free up some driveline length. The bell housings and such are the same - flywheel excluded - as the SBC or ‘LS’ engines, which makes it simple.

    With ~200hp and 260 ft. lbs. of torque, the 4.3 is certainly strong enough…

    I’ll likely replace the T15 three speed with an SM465, so keeping engine & transmission in the same family makes for less grief, I think. I’m not interested in reinventing the wheel.

    Jon
     
  2. May 17, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,532
    Room? Why do you need more room? The engine compartment has been stretched by 5" already, to accommodate the 232/258. You can put a V8 in an early Jeep, with a 5" shorter engine compartment. Not a problem for the truck 4-speeds ... done a lot.
     
  3. May 19, 2022
    sterlclan

    sterlclan Member 2022 Sponsor 2021 Sponsor

    exploring the...
    Joined:
    Feb 21, 2009
    Messages:
    3,719
    just put a 4.3 in the wifes 76 cj7 used an sm465 with a dana 300 . plenty o power. still ended up making new driveshafts. not shorter that way.
     
  4. May 19, 2022
    Jw60

    Jw60 WRPD855 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Sedalia MO.
    Joined:
    Apr 8, 2008
    Messages:
    2,751
    I luv me 4.3 you should have plenty of room for the serpentine belt, but for the work you could also do a 350 v8 with a short water pump.

    The ls line of v8 also has advantages and disadvantages.

    The 4.3 is great for the short hood but is not cheaper than a 350.
     
  5. May 19, 2022
    Jon B.

    Jon B. New Member

    SW Minnesota
    Joined:
    Apr 6, 2022
    Messages:
    27
    It may be decided as of today.

    I scored an SM465 from an ‘88 one-ton Chevy, with bell housing, flywheel, clutch plate & disc and the hydraulic clutch master, slave and plumbing. The clutch fork is there, as well.

    The tranny has an aluminum top cover, so is correct for that model year. Two wheel drive but the Novak adapter works for that, too.

    The guy that had it wanted just the 350 in front of it but had to buy the whole works. I cheerfully gave him his asking price: $200. I did have to drive nearly three hours to get it but am ok with that.

    He has another one from a ‘76 Blazer but will only sell it with the t-case.

    Jon
     
    Buildflycrash and Fireball like this.
  6. Jun 20, 2022
    Jon B.

    Jon B. New Member

    SW Minnesota
    Joined:
    Apr 6, 2022
    Messages:
    27
    Responding to my own post…

    I’m going to look at a ‘91 Chevy pickup tomorrow. It has a ‘92 4.3 with fuel injection and a five-speed.

    The seller wants $250 for the whole thing! I want just the engine & accessories and the flywheel. The 465 will go behind it.

    Vroom!

    Jon
    ‘72 CJ5 (with a bad 304 & T15 transmission)
     
    Buildflycrash and Fireball like this.
  7. Jun 20, 2022
    Twin2

    Twin2 not him 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Virginia Beach, VA
    Joined:
    Apr 28, 2011
    Messages:
    5,172
    no bone in this fight but 72 and later a V8 hands down
    now I would do a ford , distributor up front
     
    wheelie, timgr and Ol Fogie like this.
  8. Jun 20, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,532
    Isn't there something that makes a SBF fit in the Intermediate engine compartment? Like 2 left side frame towers and it drops in? My only issue with a SBF might be the native fuel injection. Plenty of hot 302s out there with multiport, but supposedly it's not as portable as the GM efi.

    Used to be you'd want the Bronco oil pan, with a rear sump.
     
  9. Jun 20, 2022
    CJ5Jeeper

    CJ5Jeeper Teacher Jeeper

    Apple Valley, CA
    Joined:
    Jan 28, 2015
    Messages:
    89
    I can't imagine getting rid of a V8 for V6. I get it's more modern (and may even have comparable power), but do you know how many Wrangler guys wish they had a V8, and yours came from the factory that way? Thank you AMC! Just my opinion, which isn't worth much these days. Good luck either way.
     
    johneyboy03 likes this.
  10. Jun 20, 2022
    Jon B.

    Jon B. New Member

    SW Minnesota
    Joined:
    Apr 6, 2022
    Messages:
    27
    The 304 is junk, in this case. A rod came through the oil pan on the left side. To me, it’s not worth repairing.

    I’m no fan of the AMC V8, except maybe the 401 high performance version. Even that doesn’t have anything on a GM 400, whether small- or big-block.

    As was mentioned, the Fords have a front distributor, which makes the fit somewhat easier. I have no love at all for Ford parts, though. None. In fact, I’d keep the 304 rather than use a SBF engine.

    I’ll be using a GM 465 four-speed, mated to the D20 t-case. The transmission and adapter add a few inches to the driveline; using a v6 takes ~4 inches back out. That’s all I hope to accomplish. The 4.3 has enough power to move a CJ5 - probably more than a stock 304!

    Jon
     
  11. Jun 20, 2022
    Jw60

    Jw60 WRPD855 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Sedalia MO.
    Joined:
    Apr 8, 2008
    Messages:
    2,751
    The 4.3 is in no way more modern than a 350. It's fine for this goal but it does have some weaknesses since it was the cheap engine of the day.
    2 oil galleys instead of 3, crank journals are split for even fire.
    92 should be a decent year especially from a full size truck but it's not 200hp it's only in the 160s due to poor heads and being built for higher load per cubic inch.

    Look at the front of the motor there should be 4 tapped holes and no fuel pump boss. Water jacket should be square and oil pan should be steel. Non balance shaft motors are easier to work with as they accept v8 accessories. Rear should have a one PC rear main. It should have a small body distributor and two barrel throttle body. Make sure you get all the tin for the intake and exhaust manifolds. All the accessories. The pilot bushing will likely be special as the flywheel is different than the two PC rear main motor the sm465 fits.
     
  12. Jun 21, 2022
    47v6

    47v6 junk wrecker! 2022 Sponsor 2021 Sponsor 2020 Sponsor

    USA
    Joined:
    Oct 25, 2006
    Messages:
    5,424
    1992 could have 160 or up to 200 depending on what model
    https://en.wikipedia.org/wiki/Chevrolet_90°_V6_engine
    My 2000 GMC safari van doner has something like 190. The flywheel is special on these and I had to buy one to swap to my SM420 from the 4L60E. My engine requires 58lbs of fuel pressure or it wont run. I used the vans fuel pump. I also ditched the wiring harness and bought a Howell one and had them flash a GM computer to get rid of VATS and disable the auto transmission stuff. It was worth the money.

    I had a 304 in my 77 CJ5. It was an ok engine that I did nothing to and just drove it. It is however inferior to the Buick 225 and I feel the 4.3 is a better more modern engine than the 225. They are everywhere and if you blow one up, 3 more appear. Parts are readily available as well. I think its a great choice and I really like mine in my flat fender.
     
  13. Jun 21, 2022
    Jw60

    Jw60 WRPD855 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Sedalia MO.
    Joined:
    Apr 8, 2008
    Messages:
    2,751
    If it is a 92 CPI in a 91 TBI truck I would be very reserved in bringing it home.
     
  14. Jun 21, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,532
    I would think, if you are getting rid of the 304, it's an opportunity to install a much more modern engine, with native MPI. If you can handle the swap generally, I'd think you could handle the MPI transplant, especially if it's a Chevy.

    I'd also think - why put a V6 in this Jeep when there's plenty of room for a V8? The V6 is just another small block Chevy, and a V8 Chevy seems like the obvious choice, if you must use a Chevy. The V6s are nice for the early Jeeps that came with the 134, since they have a fairly short engine compartment. '72 and later came with inline 6s, and the engine compartment was lengthened to accommodate them. Plenty of room for a V8. Are there fewer Chevy V8 donors out there than V6s? The MPI SBC V8 is popular for early Wagoneers, and they seem to have no trouble finding donors.

    Seems to me these Chevy V6s exist because the public views them as "modern" and economy engines, not because they are necessarily less powerful or more economical than a V8 of similar displacement. They are compact, which makes them appealing to design a car around, but I don't see the clear functional improvement over the inline 6, or a small V8.
     
    Last edited: Jun 21, 2022
  15. Jun 21, 2022
    johneyboy03

    johneyboy03 The green beast

    Quebec, Canada
    Joined:
    Jan 15, 2011
    Messages:
    2,049
    I would not swap anything else than a chevy LS base engine. Like other said, going from a v8 to v6 you will regret. 4.3 tbi style engine or LS engine is the same job, the LS with the right part will be even easier. The 4.3 tb are a pain to work out the ecm (tune)

    A 4.8 or 5.3 is cheap to get. Those v8 are 5 inch shorter than the amc v8. From there you can swap out the sm465 and a adapter for the d20. Put a good painless wiring kit and get the ecm program and it will be an easy swap.
     
    FinoCJ likes this.
  16. Jun 21, 2022
    Jon B.

    Jon B. New Member

    SW Minnesota
    Joined:
    Apr 6, 2022
    Messages:
    27
    I called off my drive to see the donor truck this morning.

    I am having second (third?) thoughts about the 4.3 transplant. Son 2, a diehard 5.3/6.0/6.2 fan has been ragging on me to go with an “LS” engine. ( I quoted it since they’re not all in the LS classification).

    If 200 horsepower are enough, why not have 300? If I keep the 3.73 axles, the extra power may come in handy depending upon wheel size.

    Jon
    ‘72 CJ5
     
  17. Jun 21, 2022
    Ohiowrangler

    Ohiowrangler Member 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Newark
    Joined:
    May 29, 2019
    Messages:
    184
    Depending on what type of riding you plan on doing, at 3 MPH, 300 HP is unusable. Especially if it"s not reliable. Just my opinion. I building a cj5 with a 4.3/T18/20. Ron
     
  18. Jun 21, 2022
    Jw60

    Jw60 WRPD855 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Sedalia MO.
    Joined:
    Apr 8, 2008
    Messages:
    2,751
    The tune on a TBI 4.3 or 350 is not a huge ordeal if you have the original pcm and all. The company that did my tbi kit will do a "tune" on it's own.
    Biggest issue is that they stopped making those pcm's a long time ago and it's 30yr old electronics that may or may not survive the transplant.

    A 4.8 is a viable option but there is a lot of stuff to make it work. If you're son is able to handle making an ls or lq run i'ld go that direction but if you are doing the work, do what you are comfortable working with.

    And (again) the 4.3 is not any less expensive than a 350 swap.
     
  19. Jun 21, 2022
    duffer

    duffer Rodent Power

    Bozeman, MT
    Joined:
    Sep 17, 2009
    Messages:
    3,609
    No, you miss the point entirely. Maybe just me, but I firmly believe you need a big gob of low end torque to have a vehicle that works well both on and off road. It isn't that peak 300 hp. It's all about what torque is available from about 500 to 1500 rpm. And here, that LS advantage over Gen I really doesn't exist. At least doesn't exist if the Gen I engine is properly set up for this. If one already has the bell housing/clutch for a Gen I, the most expedient path here is the ubiquitous 350. Or if you really want some low end torque, put together a 383. Very cost effective and doesn't have the pitfalls of the 400. There isn't any real difference in the economy between a 350 and a 383 in my experience. Absolutely go with EFI and roller cams with their steep ramp options make for the best low end.
     
    SFaulken and FinoCJ like this.
  20. Jun 21, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member 2021 Sponsor 2020 Sponsor

    Bozeman, MT
    Joined:
    Jul 18, 2013
    Messages:
    4,503
    The OP has gotta do what works for him, but my next engine swap/build will be a stroked SBC 383 with roller, hi lift short duration cam, EFI, vortec style heads rtc..I am already loving the basic sbc350 I put in the 58...kind of makes the 225v6 in the CJ seem a bit less fun for cruising. V8 power is addicting....
     
    Buildflycrash and Jw60 like this.
New Posts