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head gasket question

ksurfer2

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To increase my compression a bit, and get a better handle on the internals of my engine, I am looking to replace my head gaskets. I have a 440 based 512 using a 440 source kit. I have searched but cannot find the proper bore size I should be looking for. I plan to go with a Cometic gasket. They have a .027 thick gasket in a 4.250, 4.350, 4.410, and 4.500. Which would be the proper bore for my application? Any help would be appreciated.
 
What cylinder heads are you using. Make sure the fire ring does not overhang the combustion chamber. I heard the early Edlebrocks had this problem.
 
What is your bore size.
4.375?
4.380?
I think they make gaskets for up to bore 4.380.
 
What is your bore size.
4.375?
4.380?
I think they make gaskets for up to bore 4.380.
At this point, I would need to take the heads off to measure the bore. I was hoping the 512 kit had a standard bore size to work with. What I am trying to avoid is taking the engine apart to measure and then waiting for weeks to get the proper size gasket and get the car running again.
 
That kit comes in several bore sizes. The largest they list is 4.375". There is only one way to tell what your bore size is, and that is to measure it.
 
That kit comes in several bore sizes. The largest they list is 4.375". There is only one way to tell what your bore size is, and that is to measure it.
Thanks. Looks like this will be a summer project when it is too hot and rainy to get much racing done down here in FL.
 
No paper work from the engine build?
 
Based on the info that I was provided about the engine, and a chart I found on the 440 source website, the bore is either a 4.350 or a 4.357. Cometic site lists gaskets with a 4.350 bore or a 4.410 bore. Is narrowing down my bore size to the range I found enough to select the correct gasket, or am I still tearing down to measure?
 
Based on the info that I was provided about the engine, and a chart I found on the 440 source website, the bore is either a 4.350 or a 4.357. Cometic site lists gaskets with a 4.350 bore or a 4.410 bore. Is narrowing down my bore size to the range I found enough to select the correct gasket, or am I still tearing down to measure?
Screenshot_20221129-134800_Chrome.jpg
 
If the engine runs good why bother. A reduction from a 40 thousands gasket to a 27 is only going to raise the compression from say 10 to 10.2
Not really a noticeable change IMO
 
I’d agree with the above statement........ but do we know if it currently has .040” gaskets?
Or something thicker?

A feeler gauge stuffed between the head and block in the appropriate spot would answer that.
 
If you really up the compression, mill some off those heads while changing the gaskets.
 
I’d agree with the above statement........ but do we know if it currently has .040” gaskets?
Or something thicker?

A feeler gauge stuffed between the head and block in the appropriate spot would answer that.
I checked the gap between the head and the block and came up with .049. A change to a .027 would be a .022 difference....would that be worth the effort for the gasket change?
 
If you really up the compression, mill some off those heads while changing the gaskets.
Would this mess with the alignment of the intake? How much would need to be milled off to make a difference without affecting alignment.
 
What about your quench distance? If you have a zero or positive deck piston height you may not want to run a gasket less than say .035. Piston to head collision is hard on rod bearings.
 
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