ejscarfo

I have a line on a short block from a 1981 C3. It's an L81 350, Code ZDD 190HP / MT, casting 14010207, which I believe is the same casting number as the block in my 85. I'm being told it's a 4 bolt main. Can I use this block to build a mostly stock L98? I plan to just use the block and the crank, provided the crank is still good.

Raidmagic

Yes you can. Confirm on your current motor and the new motor the rear main seal is 2 pieces. I think it changed in late 86 or 87 to a one piece other than that you should be good to go

Ray Quayle

Damn Steve! Don't see you here much any more. If the short block is truly from an '81, you're fine. One piece rear main seal started in '86 so the '81 short block will be fine with your '85's flexplate.

ejscarfo

That's what I thought, I just wanted to be sure. I plan on starting a little engine build project to teach my son and I wanted a block that will drop into my 85 once its done. I think we might make this motor a stroker motor

mtwoolford

for the few things that have to be changed over, mainly oil pan and flywheel / flexplate, and shorter push rods, why put money into rebuilding a two piece rear seal block that is limited to running flat tappet cams with all their issues of premature failure since all the zinc (and probably other additives) were removed from motor oils ? especially if you're contemplating a stroker motor ?

consider that an 86 up block has better sealing (one piece rear seal and one piece pan gasket); runs stock hydraulic roller cams with, everything else being equal, more area under the cam lobe than an equivalent flat tappet cam lobe, and has a factory cam thrust plate.

in any case enjoy the build with your son. there should be more dads like you.

Ray Quayle

Be careful here. The '86 block is a one piece rear main seal block, but has no provisions for the factory roller cam. If you decide to go the roller route, look for an '87 up block.

ejscarfo

Thank you for the compliment and the advice.

I know about the later motors being "roller motors" and while I'd love to do one of those, I'm not too sure how it will work with the 85's stock ECM should I decide to drop this motor into my 85 once its done (I'm still toying with idea of just buying a rebuilt unit from Jasper and keeping my core for my rebuilding lesson). If there will be no issues, then I will look for a newer block to rebuild.

John A. Marker

I am not 100% sure on this statement....but if you go to a strocker (like a 383) you just might have to have a new chip burned for it. If this is the case then go for a roller block.

Usually you have to change the chip if you change the cam from stock. The 85 chip will compensate for most changes like heads, intake and exhaust. Going to a 383 just might require adjustments to the chip.

Raidmagic

Hey Ray, how have things been with you?

coupeguy2001

A couple things......
1. You might want to sonic check the block in the pan rail area before going to a 383/400 crank.
Sometimes the water jacket is thin in that area where you have to relieve the block for the rod clearance.
2. The piston/head quench area needs to be thought out for the 85 computer.
The 383 ups the compression ratio even with 14cc dished pistons.
Not sure that yoou can find pistons with a 16cc relief.
That relief is for the 58cc aluminum Chevy head. If you use a 64cc head, you may not have a problem and can use the thinner head gaskets.
Use .060 compressed head gaskets instead of the .040 compressed head gaskets to avoid a detonation problem with the 58cc heads.....

Muffin

Roller block is the way to go. A 383 is kinda a big step. It will not like either your intake, exhaust or your injectors for starters. Unless you are looking for gobs and gobs of torque a roller 355 will meet your needs just fine.

383vett

A 2 piece rear main seal non roller block can easily run a roller cam with retro roller lifters. I've been running this type of setup for years. Currently I'm running a World Products 2 piece main block with a roller cam. The op won't need to change the flywheel or flexplate.

Ray Quayle

Not bad. Car still in bits, but making progress.