11.1:1 Comp...
01-19-2010, 09:41 PM
#3
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If he's polishing the combustion chamber he will need to mill the heads because a gasket alone won't be enough. He will gain 1-3cc in the heads after cleaning up the chambers, which won't lower compression much but it's a factor. After doing the chambers he should cc and then decide how much he wants milled.
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01-20-2010, 11:50 AM
#10
Felpro is one maker:
http://www.summitracing.com/search/?...%20chevy&dds=1
It's for a Gen1 SBC, but all you have to do is use your old LT1 gasket as a template and cut out the holes for the reverse cooling.
Yes, it's a thin gasket, so I suggest checking both heads and block for flatness if you decide to use it. If all is well, it's as good as, if not tougher, than a thicker gasket. If all is not perfectly flat, then mill the heads slightly, and still use it. With a decent size cam and tight quench, 11.5 is not too much CR on an LT1.
http://www.summitracing.com/search/?...%20chevy&dds=1
It's for a Gen1 SBC, but all you have to do is use your old LT1 gasket as a template and cut out the holes for the reverse cooling.
Yes, it's a thin gasket, so I suggest checking both heads and block for flatness if you decide to use it. If all is well, it's as good as, if not tougher, than a thicker gasket. If all is not perfectly flat, then mill the heads slightly, and still use it. With a decent size cam and tight quench, 11.5 is not too much CR on an LT1.
01-20-2010, 08:24 PM
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I had the shim gasket on my old Pontiac. I trust it with iron heads, but I have never tried it with aluminum. My concern would be the added heat transfer from the block to the heads by a steel shim and the expansion qualities of aluminum. But if there are people here who have had no problems with it on an LT1 I guess it must be OK. Good to know.
01-20-2010, 08:34 PM
#15
I had the shim gasket on my old Pontiac. I trust it with iron heads, but I have never tried it with aluminum. My concern would be the added heat transfer from the block to the heads by a steel shim and the expansion qualities of aluminum. But if there are people here who have had no problems with it on an LT1 I guess it must be OK. Good to know.
01-24-2010, 11:31 AM
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Don't guess, calculate.
Use one of the compression ratio calculators on the internet. Punch in your current engine specs and your current head gasket thickness. Don't GUESS on the gasket thickness, be precise, look it up if you don't know what it is. Your stock head gasket may be as thick as .051", but check to verify.
Then click on the calculate button and once the calculations are completed, make sure the CR number matches what the factory CR spec is. That's your starting point.
Now, change ONLY the head gasket thickness in the engine spec area and re-calculate.
Doing it that way will tell you how much CR you'll gain with just a head gasket change. If your combustion chambers are 54 ccs, and if your stock head gasket is .051" and if your stock CR is 10.4:1 you can get 11.1:1 with only a swap to a .026 head gasket according to the calculations I just ran.
Verify by running the numbers yourself.
Jake
Use one of the compression ratio calculators on the internet. Punch in your current engine specs and your current head gasket thickness. Don't GUESS on the gasket thickness, be precise, look it up if you don't know what it is. Your stock head gasket may be as thick as .051", but check to verify.
Then click on the calculate button and once the calculations are completed, make sure the CR number matches what the factory CR spec is. That's your starting point.
Now, change ONLY the head gasket thickness in the engine spec area and re-calculate.
Doing it that way will tell you how much CR you'll gain with just a head gasket change. If your combustion chambers are 54 ccs, and if your stock head gasket is .051" and if your stock CR is 10.4:1 you can get 11.1:1 with only a swap to a .026 head gasket according to the calculations I just ran.
Verify by running the numbers yourself.
Jake
Last edited by JAKEJR; 01-24-2010 at 11:42 AM.
