I'm in the process of building a new motor and had a question on what thickness head gasket to use to get optimum quench. It's a L98 short block with the factory 12cc dish pistions and ported 416 305 heads. I plan to mill the heads to acheive about 10:1 compression ratio. The pistons are .020 in the hole at TDC. Does anyone have a formula for determining head gasket thinkness to get optimum quench. .040 I believe. Or is it as simple as subtracting .040-.020=.020?

 

lol, i kinda had the same problem on figureing out the gasket stuff...
then i looked on summit & jegs, & it gives you the #'s... so i was like.. shibbian chester(cool).

that's been my main crap lately, trying to figure out what compression i'd get w/ the engine i wanna build. & gaskets play a big role iv'e found out. so does the quench, .

 

You won't need to mill the heads to get 10-1 they are 58cc so they will be 10-1 with the standard .038 gasket.

 

It's as simple as that.

 

Thanks guys!

 

Let us know how that combo works out. Their are a lot of skeptics of the 416 and 601 castings potential.

 

I'll be sure to let you know how it turns out. They are only mildly ported though. I have a friend at a machine shop so I might get them flowed and see how they are. At this point I just wanted to improve them some and save my pennies for some Trick Flows.

My next question is I based haveing to shave my heads on a .041 gasket to acheive 10:1. With a .038 gasket I got 9.7:1. If I was to use a gasket with a compressed thickness of .020 I would have 10.1:1 and .040 quench. Does anyone know who makes a .020 head gasket? Should I not worry so much about quench and just mill the heads to get 10:1 with a more common gasket?

 

fel-pro #1094 is a steel shim gasket with .015" thickness if that helps you out any

 

Thanks, but I'm going to go with a standard Fel-pro .031. It won't give me optimum quench but I have heard bad things about the steel shim gaskets from several people who know much more than me. I would feel better using a slightly thicker composite gasket. I'll shave the heads slightly to get the compression up to about 10:1.

 

I used a set of GM gaskets that SDPC sells that is .028 compressed for my optimum numbers. I was .015 in the hole so with that gasket I was .043 quench distance and 10.15:1 compression which I was very happy with. I can't remember the part number but those gaskets would put you at .048 quench which should work very well for ya.

 

Are those steel or composite? The only ones I could find that thin were steel.

 

http://www.sdpc2000.com/cart.asp?act...id=576&pid=651

 

Thanks!

 

I'm with Tom on the GMPP .028 composition gaskets. They are good pieces. I've got 2 motors under my belt using them (one being my 383 supercharged motor). They are every bit as good as the Fel Pro .039" rebuilder head gaskets as far as sealing up and staying put, but they are much easier to get quench height established with.

With factory dished pistons please realize that you don't get much benefit from quench anyway. They are dished out even in the areas where they meet with the flat part of the heads at TDC. An aftermarket piston like the Keith Black 12cc D-dish hypereutectic piston will do much better as far as quench goes, while maintaining the same compression as a factory slug.

 

Right after Tom posted that I picked up SDPC catlog and looked and found those right under under the steel shim ones. Sometimes I suprise myself by not seeing things right in front of me.

I do realize that the factory pistons are far from ideal but I want to try to get as close as possible to a good quench.

Thanks guys.