1986 iron head l98 corvette valve spring question

Using 91 octane, you could raise your compression some and gain some TQ/HP, but I'm not
sure if you agree with my numbers (7.38/9.58). Help me understand if your opinion still differs,
your number for DCR at 9.10 is substantially different and way too high for 91 octane gas.
 
I thought Jeremy's SCR/DCR numbers were off. Rick's new numbers seem correct with your .041" thick head gasket and .020" deck clearance.
Change to a thinner head gasket, like .021".

1. 4.00 bore / 3.48 stroke
2. 350ci
3. 5.700 rod length
4. Afr 190 vortec (flow sheet attached)
5. 65cc combustion chamber
6. Flat top with 5cc valve reliefs
7. .020 deck
8. 4.166 head gasket bore
9. .041 head gasket compressed thickness
 
Using 91 octane, you could raise your compression some and gain some TQ/HP, but I'm not
sure if you agree with my numbers (7.38/9.58). Help me understand if your opinion still differs,
your number for DCR at 9.10 is substantially different and way too high for 91 octane gas.

I definitely agree with your numbers.
 
I thought Jeremy's SCR/DCR numbers were off. Rick's new numbers seem correct with your .041" thick head gasket and .020" deck clearance.
Change to a thinner head gasket, like .021".

1. 4.00 bore / 3.48 stroke
2. 350ci
3. 5.700 rod length
4. Afr 190 vortec (flow sheet attached)
5. 65cc combustion chamber
6. Flat top with 5cc valve reliefs
7. .020 deck
8. 4.166 head gasket bore
9. .041 head gasket compressed thickness

Bump up my compression alittle I would like. just went with that cause afr recommend to use that when I changed the heads last winter, at the time they told me my compression would be right at 10 which I thought was good so didnt question it.
 
After seeing Loves302Chevy post, I see where your quench distance is too big (.021 + .041 = .062").
So he is right, you need about a .021 inch thick head gasket. That will bring the quench distance down
to .042 inches, nearly perfect.

I'm using these SCE copper head gaskets. You don't need to o-ring the heads. Just use something like
Permatex Copper Spray-A-Gasket. Search for it on here Grumpy should have several posts about using
it. It's actually turned out to be cheaper in the long run, I've had the heads off twice now. So I'm on my
3rd time using these gaskets.

This gasket is .021 inches thick and has a bore of 4.160 inches.
NOTE: The price of $48.90 is each, so double that for your engine.

https://www.summitracing.com/parts/sce-p111521/overview/
upload_2020-1-1_10-36-46.png

https://www.summitracing.com/parts/ptx-80697
upload_2020-1-1_10-33-20.png

Note the changes are in RED numbers.
Advancing the cam timing 4° is not the best way, but it's easily doable.

Sim01_DCR_With_3_Options.jpg
.
 
Last edited:
I agree, a 62 quench is way too much. you can also get a .021 steel gasket also. You might have to look around, but they are about 17-23 bux a piece.
 
After seeing Loves302Chevy post, I see where your quench distance is too big (.021 + .041 = .062").
So he is right, you need about a .021 inch thick head gasket. That will bring the quench distance down
to .042 inches, nearly perfect.

I'm using these SCE copper head gaskets. You don't need to o-ring the heads. Just use something like
Permatex Copper Spray-A-Gasket. Search for it on here Grumpy should have several posts about using
it. It's actually turned out to be cheaper in the long run, I've had the heads off twice now. So I'm on my
3rd time using these gaskets.

This gasket is .021 inches thick and has a bore of 4.160 inches.
NOTE: The price of $48.90 is each, so double that for your engine.

https://www.summitracing.com/parts/sce-p111521/overview/
View attachment 13347

https://www.summitracing.com/parts/ptx-80697
View attachment 13346

Note the changes are in RED numbers.
Advancing the cam timing 4° is not the best way, but it's easily doable.

View attachment 13349
.
Definitely, and would rather swap the head gasket then put the timing up
 
Back
Top