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Thread: Buick 3.8 MPFI conversion

  1. #1
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    Buick 3.8 MPFI conversion

    Need some help with a new DD project I'm considering. The heart is a 1978 Buick 3.8 V6, carb'd of course. It's got issues. I'd like to do an MPFI conversion, which should be doable with the 1227730 and some other junk I have lying around. My issue is, the hardware. What intake manifold can I fit on this engine? I read the 84-85 FWD cars had the MPFI with a distributor, well, good luck finding a FWD car that old around here. I also read Buick didn't change the top end until 1995, it'll be easier to find a late-80's to 94 car to pluck parts off, if they fit of course. It looks like this car has some space behind the engine so a transmission facing TB may not be a deal-breaker.

    I'm not opposed to SEFI either if the distributor gets in the way....tips on converting?

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    I believe 84/85 were the only years that used the distributer with the efi. But I also believe that engine had the reduced deck height from your 1978 version so I am not sure the intake will fit(reduced deck height started in 82 for fwd).

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    Fuel Injected! TINBENDER59's Avatar
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    I would look into a complete late model FWD, convert it to a RWD use the coil packs, and complete EFI system with a metric 4l60e???? all 3.8's had all provisions for FWD or RWD just depended what the game was. Some Camaros had RWD 3.8's and 4l60e's. Do some resarch at the local pull apart to see if the front cover/ballencer off of a late model would fit yours, then forget the dist?? not sure what to advise. I can throw ideas but with out one to actually look at I dont know exactly where to send you

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    Fuel Injected! TINBENDER59's Avatar
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    Quote Originally Posted by mecanicman View Post
    I believe 84/85 were the only years that used the distributer with the efi. But I also believe that engine had the reduced deck height from your 1978 version so I am not sure the intake will fit(reduced deck height started in 82 for fwd).
    I believe the only thing different in the long block was the intake????

  5. #5
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    It's tough to find conversion info, seems no one converts earlier engines to EFI. It shouldn't be a problem, 78 was the first year for even-fire engines. Other reason is I don't want to do an engine swap if the current one runs good. Also it's a four speed, which I'd like to keep.

    I do know they made some changes for FWD, well what about the RWD intake manifolds off the Turbo Regal? That should work?

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    Super Moderator dave w's Avatar
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    Quote Originally Posted by Accrdwgnguy View Post
    Need some help with a new DD project I'm considering. The heart is a 1978 Buick 3.8 V6, carb'd of course. It's got issues. I'd like to do an MPFI conversion, which should be doable with the 1227730 and some other junk I have lying around. My issue is, the hardware. What intake manifold can I fit on this engine? I read the 84-85 FWD cars had the MPFI with a distributor, well, good luck finding a FWD car that old around here. I also read Buick didn't change the top end until 1995, it'll be easier to find a late-80's to 94 car to pluck parts off, if they fit of course. It looks like this car has some space behind the engine so a transmission facing TB may not be a deal-breaker.

    I'm not opposed to SEFI either if the distributor gets in the way....tips on converting?
    I did this conversion a few years ago. I ended up using a Buick Grand National 3.8 MPFI intake manifold (not a low cost budget option). A similar conversion could be done using 1985 Buick Le Sabre Intake and engine management system, it's the same EFI system used to operate a Dodge Slant Six http://www.slantsix.org/articles/dib...conversion.htm



    dave w
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    Last edited by dave w; 11-25-2013 at 08:29 AM.

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    LC2 would be an option but good luck finding one under $1000
    '86 Grand National

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    Dave, thanks for the pictures, I now know it's doable which is a huge help!But like you said, the GN hardware is not going to be cheap. I'll also have to track down the ESC module and knock sensor. KS is only $20 but the module is 75 new! kinda takes the low buck outta this conversion.

    Also found this in some searching. Possible FWD alternative....Turbo1dr says you'd have to turn the FWD intake around to face backwards in order for the coolant flow to be correct, it'll look weird but if it means I can use a u-pull FWD intake for $20 vs GN intake for couple hundred dollars..so be it. As much as I would like to turbo it this will be a DD mileage build.

    http://www.turbobuicks.com/forums/be...rwd-4-1-a.html

  9. #9
    Super Moderator dave w's Avatar
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    Quote Originally Posted by Accrdwgnguy View Post
    The heart is a 1978 Buick 3.8 V6, carb'd of course.
    In it's 40+ years of production the Buick V6 saw many changes. I'm thinking 1978 would have used the 2G 2 barrel carburetor. Starting in 1979 the 231 was updated to metric 3.8 liter and many changes occured, namely the high port head design. Buick 3.8 liter intakes from 1979 and newer are not simple bolt on and go interchanges for 1978 and eariler Buick 231 heads. Starting in the 1979 the carburetor on the 3.8 liter was changed to the Dual Jet 2 barrel which looks like a quadrajet without the rear secondaries.
    Quote Originally Posted by Accrdwgnguy View Post
    I'd like to do an MPFI conversion, which should be doable with the 1227730 and some other junk I have lying around. My issue is, the hardware. What intake manifold can I fit on this engine? I read the 84-85 FWD cars had the MPFI with a distributor, well, good luck finding a FWD car that old around here. I also read Buick didn't change the top end until 1995, it'll be easier to find a late-80's to 94 car to pluck parts off, if they fit of course. It looks like this car has some space behind the engine so a transmission facing TB may not be a deal-breaker.
    The intake manifold design on both the Buick 231 and Buick 3.8 liter are mirror image, so the intake can be bolted on in either direction. So the Buick 3.8 liter FWD intake manifold can be bolted on 180 degrees or pointing forward like on a rear wheel drive vehicle.

    In my humble opinion, updating to a GM TBI system is the budget route to go with a 1978 Buick 231. It's a bummer your engine is not one model year newer, when all the good things happened to the Buick V6!

    dave w

  10. #10
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    Thats a bummer! I do have a TBI on the shelf I could rebuild and would have to get a harness and ECM. easy. I just like the look of MPFI better. Of course if the heads need to be re-done a headswap could fix this issue.

    I wonder if I could change out the bell housing for a 2.8 bell from an S10 and bolt in an L67. I'd have to fab mounts, since Buick removed the RWD mounting bosses from the later engines. Better to keep it simple......

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    Super Moderator dave w's Avatar
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    Quote Originally Posted by Accrdwgnguy View Post
    Thats a bummer! I do have a TBI on the shelf I could rebuild and would have to get a harness and ECM. easy. I just like the look of MPFI better. Of course if the heads need to be re-done a headswap could fix this issue.

    I wonder if I could change out the bell housing for a 2.8 bell from an S10 and bolt in an L67. I'd have to fab mounts, since Buick removed the RWD mounting bosses from the later engines. Better to keep it simple......
    I have ventured down this Buick V6 interchangeable path, and it provides many headaches and costly detours! To the best of my memory, the High Port Buick 3.8 liter heads will not work on the 1978 Buick 231. For me the answer was to get a complete 1980 - 1984 RWD engine from a RWD Regal or Camaro. I ended up getting a complete Buick 3.8 liter engine from a 1980 Camaro. I was able to get a complete fuel injection system (wiring harness, ECM, MAF, distributor, intake manifold with fuel rails & injectors) from a 1985 Buick Electra. I had planned on using the Electra FWD intake, but did not like the idea of the intake pointing at the firewall. There is no way to install the Large Cap HEI distributor from the Electra with the intake pointing at the radiator. With some AWESOME luck, I found decent prices on some Grand National intake parts. I needed to modify the Grand National intake to make clearance for the large cap HEI from the Buick Electra.

    The dirt cheap EFI option for the 1978 Buick 231 is TBI. The 1985 Buick Electra distributor will play nice with a TBI computer (1227747). The 1985 Buick Electra distributor is an ultra simple bolt on to the 1978 Buick 231. If your set on MPFI for a RWD Buick 3.8 liter, the budget will get HUGE! If you decide to go with a FWD MPFI Buick 3.8, the budget will need to be even bigger!!!

    dave w

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    Have some big ideas on conversions with bigger motors Im thinking about and possibly a nice little fairly simple conversion has dropped into my lap to get my feet wet with. I just purchased a 1978 Pontiac Sunbird/Astre wagon that someone had put a 215 Buick V8 in. I bought it minus the engine from the transmission back. I have 2 Buick 231 V-6 motors, one in an 80 Firebird and one in an 84 rwd Cutlass. Cutlass is a low mile motor I took care of. Has an auto trans. Sunbird has the original 4speed manual trans. I would like to tbi the 84 3.8 once I have gotten it in and debugged with carb setup. Currently has a 2jet on it I believe. Not sure what parts would make the conversion easiest and simplest .. would like to find out and get them. Its not a racecar, hoping the tbi would improve fuel economy and not lose performance. Cutlass was a gas-hog with the carb v-6 to the point I wondered if something was wrong but never blew out black smoke and seemed to run ok.

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    Super Moderator dave w's Avatar
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    The basic nuts and bolts to install TBI on the 84 3.8 V6.

    Start with getting EVERYTHING from a 4.3 TBI engine that was using the 1227747 computer.
    Custom fabricate a TBI to Dualjet adapter plate.
    Use a HEI distributor from a 1985 Buick Electra 3.8 liter.
    Simplify the 4.3 TBI harness for stand alone.
    Install an O2 sensor bung into the exhaust.
    Install a fuel injection fuel delivery system. Maybe find a 1985 Monte Carlo 4.3 TBI gas tank?

    Rewire the 4.3 V6 distributor wiring to work with the 1985 Buick Electra distributor. The 4.3 distributor is an 8 pin ignition module, the 3.8 is a 7 pin ignition module. The 4.3 uses a remote mounted ignition coil, the 3.8 has the ignition coil in the distributor cap.

    Burn a custom chip.

    dave w

  14. #14
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    Ok this becomes my recipe.

    1. EVERYTHING includes items available when I pop the hood in a junkyard or do I have to get underneath the car? I do not need the intake manifold? How do I identify the 4.3 if radiator support sticker is not intact? Do I have to tear apart dash to get to computer?

    2. If I am fabricating an adaptor plate this means I can choose intake manifolds to adapt to, I have a Kenne Bell single plane that fits. Is there a manifold characteristic that I should be looking for? maybe just take the 4.3?


    3. Will look for that distributor ... what is the reason the remote coil distributor is necessary? Just curious.


    4. Harness simplification ... what is standing alone? Computer not adjusting spark advance?


    5. Understand o2 sensor ... car will need exhaust anyway ... is there a reason sensors are not placed in exhaust manifolds rather than downstream? Normally 2 ahead of and beyond cat to verify its working as well as adjust fuel delivery .. right?. This one will just be adjusting fuel delivery only. Was hoping the exhaust would be a Walker bolt on affair but they have possibly trashed the H-body info if they ever had it, I cant find. Not done looking. Having trouble getting the smaller ext balanced flywheel and clutch as well.

    6. The reason an electric fuel pump is required ? The fuel must be delivered to the tbi at higher pressure than mechanical devices?? Finding a tank to fit Sunbird wagon may not be cake.

    7. Can you recommend chip burn resources? What would happen or not using the original 122747 or a HP shelf counterpart?

  15. #15
    Electronic Ignition!
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    PS Thank you for sharing that with me! .... really like this forum ...

    I tried to edit the computer number I boobed but edit didn't take when I pressed save, not sure why, happened before

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