1981 vette engine..

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Dec 13, 2006 | 03:56 PM

HighHeat303

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1981 vette engine..

Alright I have my mostly stock 1981 corvette with the original engine in it, never pulled and nothign ever messed with other than the carb... plugs stuff like that. Now im woundering what kind of internals do I have in ther? I know its the L-81 and from what i have heard it has dished pistons and 2 bolt main caps. Im woundering what kinda steel the crank rods and pistons are. I think the pistons are the dished ones

but im not sure. Any info would be great, Im pricing out a rebuild. This winter i have nothing but time and money to spend on my baby, new suspension kit, new interior, and maybe the engine too. O yeah it has 85K miles on it, I dirve it daily in the summer. thanks for any info guys

Dec 13, 2006 | 07:44 PM

Durango_Boy

Team Owner

Joined: Aug 2006

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From: Columbia Missouri

Quote:

Originally Posted by HighHeat303

I'm a little confused. You want to rebuild the stock motor back to stock, or do you want to upgrade it. If that's the case, do you want to upgrade a little or a lot?

Would you think about pulling your stock engine, and storing it, and building...say, a stroker, or a 400, or even a big block? What are your goals, and intentions with numbers matching components?

Dec 13, 2006 | 11:37 PM

Kalway

Safety Car

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From: San Diego CA

From what I've heard, the L-81 actually had forged pistons. Yeah they're a bit dished, but the huge 76cc combustion chambers don't help much, either.

Dec 14, 2006 | 05:50 PM

HighHeat303

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well

Alright im thinking about pulling the engine out putting it on a stand and rebuilding it, with a little more power, nothing to crazy, probably just a nice set of heads cam and intake, but I wanted to know what kind of pistons, rods, and crank it came with, because if the pistons are really dished, then i would consider getting some flat top pistons, and I wanted to know what kind of crank and rods are in it, so that way I know if I will be able to run say a 50-100 shot of NOS, on the stock internals. Depending on how dished the pistons are I might be able to just get a nice set of closed chambered heads to help bump the compression ratio where I want it. Really depending on what is in it depends on what I do. I probably will not be looking into boreing the engine, unless it looks like it needs it, but i dont think it will because it only has 80K on it. Thanks for any info on this engine.

Dec 14, 2006 | 05:56 PM

dgruenke

Drifting

Joined: Apr 2002

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From: New Baden Illinois

Quote:

Originally Posted by HighHeat303

With 80K miles, you probably are looking at some boring. You are almost guaranteed to have a ridge at the top of the cylinders. You will also want to check to make sure they are not out of round with that many miles.

Dec 14, 2006 | 06:12 PM

a1sensei

Melting Slicks

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From: Orange Park Fl

Your pistons are dished. Bore the block 30 over and replace them with some good flat top hypertuetics. That and a set of good heads with around 72 cc chambers should have your compression up around 9:1, which is good for a daily driver/ street machine. I have the Dart Iron Eagles with 180 cc runners and they are great. More power, reliability and efficiency than stock all for aroud $800 ready to bolt on. There are plenty of mild performance cams that will work great with this set up, giving you good power and gas milage. I did this rebuild myself about a year ago for just over $2,500 total. God bless, Sensei

P.S. Don't forget to work the exhaust while you're at it!

Dec 14, 2006 | 06:24 PM

Glensgages

Race Director

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From: State of Confusion

Quote:

Originally Posted by HighHeat303

..... I'm wondering what kind of internals do I have in there?

Unless I am WAY off-base, an L-81 (much-like the L-48 and it's Z28 brethren LM-1 ) is a 'nothing-special' small-block/4-bbl, except the L-81 has forged-aluminum pistons, where-as the LM-1/L-48 have cast slugs, all deep-dished w/ 4 eyelets for the valves:
the cylinder case is a 'standard'-design 2-bolt main-cap block, with 'production' connecting rods, a cast-iron crank, and a very mild hydraulic cam, probably not-much different than 350/4-bbls found in countless Caprice Classics and 1/2 -trucks of the era.

If it doesn't need bored, necessitating new pistons, you can probably get the car to run 13-second @ 100 MPH 1/4-mile times with a head-swap, cam/lifters/springs, ignition, intake/carb, (open ) headers, and a rear-gear swap, while keeping the RPMs below 5600-6000 RPM, running 89-91 octane fuel:
nothing earth-shattering, but much-quicker than anything-else offered 26 years ago.

Dec 14, 2006 | 06:33 PM

HighHeat303

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thanks

Thanks for all the info guys. With all that said I'm goin to start this winter with the interior, see how much money that eats up and go from there. If it eats up too much I might just wait anouther year to do the engine, because ill probably want to get carried away with it