So, my '86 GT V6 4-speed has a crankshaft with the #4 rod journal worn to the point that the biggest/smallest oversize/undersize bearing I've been able to locate doesn't take up the slack. Crankshaft Rebuilders used to sell the replacement shaft in 0.010"/0.010" and 0.010"/0.020" options, and I was sure I was going g to order one before they didn't have any more. But I didn't. Yesterday, while perusing my local fb marketplace, I found a 2.8 v6 with automatic transmission out of a 1986... S10. Which brings to the big questions - are the crankshafts interchangeable? Will the whole block fit/work in the GT? Will my heads fit the S10 block, or my intake fit the S10 heads? The price for the S10 combo makes it worth the gamble, if it's a do-able thing. Any knowledge on this is greatly appreciated. Thanks in advance - Chris
[This message has been edited by CSM842M4 (edited 03-29-2025).]
The 2.8L engine came in two versions, internal balance 88 and external balance 85-87. Its hard to tell what crankshaft went with any engine on the S-10 but you should be able to tell by the flywheel balance work or lack of it. For the amount of work needed for a 2.8L rebuild at this point you may wish to consider an engine swap . .
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Thanks, Dennis. I've actually been considering the 2.8-3.1 conversion I've seen mentioned here and offered by a vendor mentioned in the thread. The price with the options I chose was about 11x the asking price for the engine/trans combo. Not shy about the work involved, but if I can get the car on the road for less $, THEN start work on the eventual, inevitable replacement engine/transmission,...
You could have the journals turned down to 2" and use lighter and longer rods. Newer crankshafts come with smaller and lighter (and stronger) rotating assembly. It's the main reason the 3.5 LZ5 makes more power that the 3.5 LX9. A LZ5 is a destroked LZ9 which helps it rev better as well...but I digress...
In my case I also used lighter pistons. I did this to the crank from a 3100/3400 and now make more power at the wheels than a stock 3900 and 3800SC while retaining the Fiero heads and lower intake. It's amazing what newer and better internals can do!
When I had the crank rebalanced for the lighter weight of the rods and pistons, the crank lost 6-6.5lbs in counter-weights.
I guess what I'm saying is, you're trying to band-aid a problem. If you're invested in your car, you should develop a real solution. Some people fix it with swaps. Some people fix it with rebuilds. I've done both several times. Pick one and just do it.
If you replace the bearings on 1 journal, just remember the others aren't far behind. Stuff like this is why even in the case of a swap, I prefer to rebuild the incoming motor. Perhaps I just like spending money...or perhaps I like things that last.
Olejoedad - would that be just the engine, or with transmission? Where in Michigan is the engine, and/or Clarendon? What condition is the engine, or why was it pulled (I'm assuming)? Short answer, yes, if the price makes the drive worthwhile... Lou - I'm with you on the "pick one and send it", but I've had this car apart I'm my driveway for long enough that I just want to drive it and enjoy for now, while I build the "perfect" replacement and build it to last. Thanks for weighing in, fellas. Keep it coming.
Olejoedad - would that be just the engine, or with transmission? Where in Michigan is the engine, and/or Clarendon? What condition is the engine, or why was it pulled (I'm assuming)? Short answer, yes, if the price makes the drive worthwhile...
This thread has been out there for a bit, but I just stumbled across it. Late to the party as usual.
FYI... the 2.8 got a different rear main seal around 1985 - or thereabouts. Changed from a rope seal to a one piece rubber/metal seal. Not that it's applicable to the 86, but stranger things have happened. Also, be careful about S10 heads. The castings are essentially identical to the Fiero heads, but if it has (or had) a carb, it likely has small valve heads. Any EFI - TBI or MPFI - 2.8 got the large valve heads. The S10 likely has a milder cam, too. Also, the starter is on the wrong (right) side, same as the 3.4 Camarobird motor.
