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not truck related but small block chevy question

Discussion in 'Chevy Trucks' started by 83shorty, Apr 12, 2003.

  1. 83shorty

    83shorty Junior Member
    from Ohio
    Messages: 2

    I have a chance to get a 92 Caprice Classic in very good condition for free but with a bad motor. It has TBI and a 700r4. I want to take the motor out of my Firedbird and swap it in. The Firebird is an 86 TPI with and 700r4. The only problem I can think of is the change to center bolt heads and i am not sure if the intake will interchange since I will have to use the 92 intake on the 86 motor. That is the only problem that I can think of. I dont know if I will have to get a TBI intake for a earlier motor. If anybody has any comments or suggestions please let me know, I would really like to make this happen since the body on the Firebird is pretty wasted the the drive train is great. I know that this is not directly related to trucks but someone may have had experience swapping truck motors. Thanks for all of your help
     
  2. johngus

    johngus Senior Member
    Messages: 117

    Why change over to throttle body injection?Use the complete TPI motor as is,you just need toswap the ECM and harnessses.it will make the caprice much better.now its like an impala SS.just an idea,I don't know how far you want to go on the swap.LOL
     
  3. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    83 shorty. The centerbolt engines have different bolt angles on the center intake bolts,(the 4 that go around the exhaust crossover).I have swapped then before,you can make the centerbolt intake fit the 86 motor with a lot of grinding.I did it. Your 86 should be a one piece rear main seal engine,so that should be fine.Just double check both should be pass side dipsticks. I put an 85 IROC TPI 305 engine in an 88 K2500 LD 4x4 that had a 305 TBI.I would not use the 86TPI setup,it is a lot more work than Johngus would have you believe,it is doable,just not worth the effort.If you decide to do it,you need to drop the tank and change the low pressure EFI pump to a high pressure one out of the firebird or the 94-96 caprice L99 or lt1 motor.I am guessing both cars are 305's?.
     
  4. johngus

    johngus Senior Member
    Messages: 117

    i wasn't saying it's a simple conversion,sorry if it seemed that way.I was just pointing out the benefits of the TPI over the throttle body.If your just looking for a simple engine swap,sell the camaro and buy a GM crate engine.they're only probably about 1200-1400.do you think the other car is worth that?at least then you're getting a rebuilt motor with warranty.then the caprice will be around for a long time.
     
  5. johngus

    johngus Senior Member
    Messages: 117

    i meant sell the firebird.sorry.
     
  6. wyldman

    wyldman Member
    Messages: 3,265

    It is a fair bit of work to drop the TPI setup into the caprice,but it can be done.

    I wouldn't recommend putting the throttle body setup on the TPI motor,as it won't run well.The bigger cam,etc,will throw off the speed density computer and it will run poorly.
     
  7. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    83 Shorty,I did this swap,I put the TBI on the 85 5.0TPI motor,it ran fine,no problems whatso ever.The cam while it is slightly larger,the change is so small it isnt enough to throw the ECM out of wack.I did the swap on my Dad;s truck we drove it 2 yrs after with zero problems,and no check engine light either.The truck towed much better,and got better mpg than the original truck 305 also. I put in on an 85TPI which had 215HP,the 86'TPI 305's only had 195hp,they put a smaller cam,and lowered the compression on the TPI 305 in 86,along with a smaller exhaust,y pipe,and catylitc convertor.The 5 speed 305TPI's remained at 215hp until they went to the LT1 in the 93 F bodys.So the 86 motor is even closer to the stock cam/compression than the 85 motor,so the changes should be minimal if any.There is ony a 20hp difference between the 86 TPI and the 92 TBI 305,most of that is in the exhaust and intake system.
     
  8. wyldman

    wyldman Member
    Messages: 3,265

    That's interesting John.I did the same swap,but it was on an 88 pickup,305 TBI.We took an 86 TPI motor from a Firebird,and dropped on the truck throttle body setup.It ran horribly.Loping,rough,rich idle,if it would idle at all,and major hesitation and surging while driving.I even tried a few different PROM's from a larger 350,but no luck.I had some success by adding an external adjustable fuel pressure regulator,to bump the pressure up,which cured most of the drivability problems,but could never get it to idle right.We ended up replacing the cam,with a stock 305 TBI cam,and it cured the problem.

    I'm not trying to discourage anyone here,but unless your prepared to possibly run into some problems,and have the diagnostic ability,and mechanical expertise to know how to correct them,I wouldn't recommend a swap of this nature.
     
  9. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    Chris,wierd how you have trouble with the 86 cam,which is smaller than the 85's. Anyone attempting any non stock swap has to expect to run into things of this nature.Anytime you mix and match you run the risk of trouble. The truck was my Dad's so we had it 2 yrs after the swap.The truck ran perfectly the entire time we had it. I would do another one without reservation.
     
  10. wyldman

    wyldman Member
    Messages: 3,265

    Yeah,it was a weird one.I have also not had a lot of luck putting cams into the TPI motors either.We built a show quality 86 vette,with a 350 TPI.Pretty much a stock internals,and installed a computer compatable cam upgrade.The stock ECM did not like it.Same problems as above.Ended up going back to the stocker.Looking at the cam card,the specs were not very far off,I really suprised it didn't work.
     
  11. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    Chris that is strange. I had an 89 Iroc 5.7 TPI,i bought it bone stock. I put a Lingenfelter ram on it,along with SLP header,and cat back,air flow research heads,and a TPIS ZZ9 hydraulic roller cam. Thsi cam was 212 intake duration at .050,224 exhaust. It was .483 intake lift,and .534 exhaust. The car ran great with the stock prom. It had a very slight lump to the idle.I ran thsi car for abotu a yr like that.It flat out hauled a--. I considered a custom prom(500),but the car ran so good, i spent the $$ on a stall tc and gears. Cars with mass air flow sensors should run fine with moderate mods,since they measure air flow and can compensate for it. Speed density(map sensor) cars measure intake vaccum,and they usually have a harder time making big adjustments.