Engine rebuild
Thread Starter
Advanced
Joined: Aug 2004
Posts: 94
Likes: 9
From: Houston Texas
Engine rebuild
I have an 81 with a converted carb. Going to rebuild engine. All 8 plugs had oil on them when I changed plugs last weekend. But I am going to rebuild my block .30 over with 9.5-1 compression. I am not looking for a stroker motor or anything close to that. I just want 300-350 hp at motor and a good old school sounding street car. I know that cam cant be to heavy due to Vac issues. This is the kit Jegs said to use just wanted to get opinions on what you guys thought? Trying stay under $3000. Too many other toys and wife complaining! lol!! My buddy has a good machine shop that's not bad on prices. Thanks for anyone's reply!
Crank and pistons:
355ci
4.030'' Bore
Hypereutectic Flat Top Piston
10.6:1 w/58cc; 9.9:1 w/64cc; 9.3:1 w/76cc
3.480'' Crank Stroke
5.700'' Rod Length
Internal Balanced Assembly
Holley CARB 600 CFM CLEAN AIR GM
Edelbrock performer intake:
Cam and lifters
Magnum 270H Hydraulic Flat Tappet Camshaft & Lifter Kit Lift: .470" /.470" Duration: 270°/270° RPM Range: 1800-5800
Crank and pistons:
355ci
4.030'' Bore
Hypereutectic Flat Top Piston
10.6:1 w/58cc; 9.9:1 w/64cc; 9.3:1 w/76cc
3.480'' Crank Stroke
5.700'' Rod Length
Internal Balanced Assembly
Holley CARB 600 CFM CLEAN AIR GM
Edelbrock performer intake:
Cam and lifters
Magnum 270H Hydraulic Flat Tappet Camshaft & Lifter Kit Lift: .470" /.470" Duration: 270°/270° RPM Range: 1800-5800
Race Director
Joined: Mar 2016
Posts: 14,163
Likes: 7,948
From: Napa Valley California
Since you are going through the bottom end, you may be surprised to find that you can purchase a stroker kit for the same cost of replacing the parts you have listed. All three performance machine shops I went to agreed that adding the stroker kit is free hp/torque gain. I'll be stroking my 454 to 496 cu. in. using an Eagle stroker kit. Determine what you want from your total rebuild, where you need torque and hp gains, what you plan to do with your car and how you want your car to perform with your transmission and rear end gearing. Do your own research and talk with several machine shops and performance experts before you decide for yourself. And of course run your plan through your wife and get her approval. LOL, I have to do the same, but my wife can spend the cost of a stroker kit in an afternoon of "shopping" so she doesn't say much about the $$$'s going into the Corvette.
Last edited by OldCarBum; Jan 20, 2017 at 02:33 PM.
Drifting
Joined: Jun 2012
Posts: 1,990
Likes: 183
From: Port St. Lucie Fl
I have an 81 with a converted carb. Going to rebuild engine. All 8 plugs had oil on them when I changed plugs last weekend. But I am going to rebuild my block .30 over with 9.5-1 compression. I am not looking for a stroker motor or anything close to that. I just want 300-350 hp at motor and a good old school sounding street car. I know that cam cant be to heavy due to Vac issues. This is the kit Jegs said to use just wanted to get opinions on what you guys thought? Trying stay under $3000. Too many other toys and wife complaining! lol!! My buddy has a good machine shop that's not bad on prices. Thanks for anyone's reply!
Crank and pistons:
355ci
4.030'' Bore
Hypereutectic Flat Top Piston
10.6:1 w/58cc; 9.9:1 w/64cc; 9.3:1 w/76cc
3.480'' Crank Stroke
5.700'' Rod Length
Internal Balanced Assembly
Holley CARB 600 CFM CLEAN AIR GM
Edelbrock performer intake:
Cam and lifters
Magnum 270H Hydraulic Flat Tappet Camshaft & Lifter Kit Lift: .470" /.470" Duration: 270°/270° RPM Range: 1800-5800
Crank and pistons:
355ci
4.030'' Bore
Hypereutectic Flat Top Piston
10.6:1 w/58cc; 9.9:1 w/64cc; 9.3:1 w/76cc
3.480'' Crank Stroke
5.700'' Rod Length
Internal Balanced Assembly
Holley CARB 600 CFM CLEAN AIR GM
Edelbrock performer intake:
Cam and lifters
Magnum 270H Hydraulic Flat Tappet Camshaft & Lifter Kit Lift: .470" /.470" Duration: 270°/270° RPM Range: 1800-5800
Pro
Joined: Jan 2016
Posts: 502
Likes: 103
From: Reno Nevada
Seems you may be getting ahead of yourself a bit. Do you know that it needs to be bored? May just need to be honed with new bearings and rings. Never truly know until you open it up. Could save a ton of $$. And, why the crank and rod replacement? If you do indeed need to replace the crank, definitely go with a stroker crank it is the same price and you will have more hp. Rods are almost definitely fine unless you change to a crank and piston that needs new geometry.
Thread Starter
Advanced
Joined: Aug 2004
Posts: 94
Likes: 9
From: Houston Texas
Thanks for all the suggestions! I really do appreciate it! I forgot to mention the heads but they are 2.02 heads. I will be using them. I am for sure going to get suggestions from the machine shop. They do it for a living! But I do value others opinions as well. For sure ones off this forum! Thanks again!
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
I just rebuilt my 81 engine a couple of years ago, I did not need a new crank so I had the old crank polished and reconditioned. The L-81 is a two bolt main engine so depending on the HP you want, you might ask the machine shop if the block can handle being converted to a 383 stroker motor. My block is bored .030 over and with the cam, intake, heads and full length headers I'm running close to 320hps. The computer is still hooked up on mine and the car runs very well. The idle is a little too mild but I can't complain.
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Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,027
I just rebuilt my 81 engine a couple of years ago, I did not need a new crank so I had the old crank polished and reconditioned. The L-81 is a two bolt main engine so depending on the HP you want, you might ask the machine shop if the block can handle being converted to a 383 stroker motor. My block is bored .030 over and with the cam, intake, heads and full length headers I'm running close to 320hps. The computer is still hooked up on mine and the car runs very well. The idle is a little too mild but I can't complain.
Dr. Detroit
Joined: Mar 2012
Posts: 10,090
Likes: 4,015
From: New Braunfels Texas
You need to have the assembly balanced.
You need to check your compression if going with 383 because they require a dish on most everything to run pump gas.
If going 383 and roller cam you will need one on a small basecircle.
I would use Eagle as they have the most rod clearance as of right now, they have profiled the rods for minimum grinding.
If going 383, you need to clearance the oil pan rail and bottoms of the cylinders.
If staying 350....keep your crank and pop for a set of Eagle SIR rods to go with the hyperutectic pistons......have it balanced. The stock crank is strong enough.
Good Luck!
Jebby
You need to check your compression if going with 383 because they require a dish on most everything to run pump gas.
If going 383 and roller cam you will need one on a small basecircle.
I would use Eagle as they have the most rod clearance as of right now, they have profiled the rods for minimum grinding.
If going 383, you need to clearance the oil pan rail and bottoms of the cylinders.
If staying 350....keep your crank and pop for a set of Eagle SIR rods to go with the hyperutectic pistons......have it balanced. The stock crank is strong enough.
Good Luck!
Jebby
Burning Brakes
Joined: Nov 2014
Posts: 920
Likes: 207
From: Foothills of the Adirondacks.
Isn't it cheaper to buy new heads instead of rebuilding old heads? Bonus, they flow better.
Melting Slicks
Joined: May 2012
Posts: 2,192
Likes: 343
From: Allenton Wisconsin
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
Machine shop work will have as much to do with good, reliable performance as the parts you put into it.
Have the mains alignment checked, deck the block to leave the pistons .005 or so in the hole and make absolutely sure you have it honed with a torque plate.
I have an '81 4-speed car, I'm pulling engine and tranny to store both, I want to keep the option of going back to a numbers-matching car someday if need be.
I'd start with a late 90's 4-bolt roller block. Scat cast crank and some of their rods, internal balance. Forged pistons aren't a necessity but nice just in case you decide to spray it later. I always take crank and rods to the machine shop so they can check and set bearing clearances for me...
Have the mains alignment checked, deck the block to leave the pistons .005 or so in the hole and make absolutely sure you have it honed with a torque plate.
I have an '81 4-speed car, I'm pulling engine and tranny to store both, I want to keep the option of going back to a numbers-matching car someday if need be.
I'd start with a late 90's 4-bolt roller block. Scat cast crank and some of their rods, internal balance. Forged pistons aren't a necessity but nice just in case you decide to spray it later. I always take crank and rods to the machine shop so they can check and set bearing clearances for me...
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
If you're going to get it decked and stay with the flat tops and 64cc combustion chamber -go with the 0.015" Felpro gasket and gain 0.5 points more compression ratio. -Run Premium.
Cast crank is fine but forged pistons is a nice upgrade for reliability.
That cam design is ancient; Look at an equivalent duration Voodoo for something more modern and higher performance (but harder on the valve train).
Adam
Cast crank is fine but forged pistons is a nice upgrade for reliability.
That cam design is ancient; Look at an equivalent duration Voodoo for something more modern and higher performance (but harder on the valve train).
Adam