Thread: To Zero Deck Or Not?

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Well,

As I work the problem in my head, It seems that using Tech's advice (a general practice) of mocking up the crank with pistons in the #'s 1,7,2, & 8 bores, measuring piston to deck clearance at each of these four corners, and then milling the deck to acheive the desired quench height with the gasket thickness to be used, ends up squaring and paralleling the decks to the crank centerline regardless of the required amount of material actually milled off the nominal deck height.

If I choose to run an .028" thick head gasket with a piston TDC height of 9.008" from the crank centerline, then I will need a Piston to deck height clearance of .0012 to acheive a .040 quench distance. This means that if the nominal deck height is at least 9.025 at the low end of each deck, that a minimum of .005" will get milled off the deck, increasing the amount of material removed at the high end of the deck. In this case, regardless of how much material is removed at the high end, I will end up with a finished and parallel deck height of 9.020". If the nominal unmilled deck height turns out to be lower than 9.020" at the low end then I will have to run a thicker gasket after milling and adjust my deck cut and head gasket thickness as necessary to maintain the desired quench distance - up to a zero piston to deck height clearance and an .040" thick head gasket.

Or, simply zero clearance mill the deck to the piston TDC height at all four corners to begin with and run a head gasket thickness equal to the desired quench height, but here's something to ponder;

Would it not be better to let the cylinder walls take as much of the quench pressure as possible, thereby reducing the potential for blowing an otherwise thicker head gasket? Are not thinner head gaskets less prone to blowing out? What about keeping he gap between head and cylinders as small as possible to reduce the amount of carbon build up?

you are making this way to hard mock it up. see what you have for head gaskets thickness and pick one thickness that is for the bore size cut it down and use them head gaskets that take to make it work if you use the 0.040 thick gaskets get it o deck or down in the hole a bit adding the pistons pc and the rod 1/2 the stroke will tell you what the deck should be. not what it really is and there is no way to get this rigth till you mock it up see what you have sticking up and give the block a hair cut

Yes Pat, that is the process I have described.

With a Piston TDC height of 9.008", the thinnest suitable gasket I am likely to be able to run while maintaining a .040" quench is .028" thick if I am able to obtain a .012" piston to deck clearance - up to .040" thick if I have to, or choose to, zero deck.

I ran through this preliminary process in order to determine what gaskets were available that would work in my circumstances.

The question is, when it comes to potential head gasket problems, are thinner better than thicker?

Originally posted by MainCap
Yes Pat, that is the process I have described.

With a Piston TDC height of 9.008", the thinnest suitable gasket I am likely to be able to run while maintaining a .040" quench is .028" thick if I am able to obtain a .012" piston to deck clearance - up to .040" thick if I have to, or choose to, zero deck.

I ran through this preliminary process in order to determine what gaskets were available that would work in my circumstances.

The question is, when it comes to potential head gasket problems, are thinner better than thicker?

I am currently running a 420sbc with 6lbs. boost with a zero deck and a .039 steel ring gasket. I also have a 10.9:1 383 that I run a zero deck with the same gasket but for a 350. It doesn't really matter about that ring thickness as long as it's a high quality pre-flattened steel ring.

yes a good head gasket try a set of mls or fel-pro with a ss steel fire ring