Deck Thickness, How Thin is Too Thin?

How thin of a deck would you consider as a 'no go'?

My beater '66 hemi block is already .080" shorter than nominal, it needs further milling from some gouges in the deck. Some gorilla tried to pull out the 1/4" dowels with vicegrips & scarred it up. I haven't had the deck sonic'd yet, was just looking for some reference.

Street use, standard head bolts/stud, stock iron heads.

This may be of help.

Decking Thread

Back in the day a lot of guys cut the deck .100” without any problems after. That’s running in Super Stock at 12.5 - 1. Plain old steel gasket too.

How does the spacer plate work ?

Is it: Block - steel shim - spacer plate - steel shim - Head ?

The reality is that it's probably not near a critical sealing area...hopefully anyway. After you gauge that, just flat-file the high spots down. We won't tell anyone it's got an aesthetic hidden flaw.

That’s the way we have done it.

If the marks are not in the load cell/bead area of the gasket then as mentioned, just lightly file to get any high spots out and be done with it.

Thanks Transman, I have been thinking about this.

What kind of compression or boost were you running with the spacer plate ?

I wish the marks were just cosmetic, but they managed to gouge all the way around and over the edge of the nearest cylinder wall, deep. Otherwise I probably would have just run it. Its bad enough I'll have to ridge ream or round file the cylinder lip in that spot.

Had numerous old Super Stock motors that came in that had the old TRW/DirectConnection 12.5 - 1 pistons that guys wanted to run on the street without anything but a smaller cam. Took the rollers out, rebuilt the motors and added the shim with gaskets.

Didn’t have any problems from any of them. You would have to use a compression calculator to figure out what actual ratio they ran at.

We did use the shim on a motor that was whacked way too much but was used in MP at 12.5 to 1 with no issues either.

That might be an easy fix at a diesel welding shop. Weld up the gouges, take only .005 cut or so to fix.

Ever double stack steel gaskets with a spacer plus another on the other side?

.021+.021+.059+.021

I've got all those on hand already, that would let me shave .010" from the block to clean it up and the compression would still be happy.

I'd hate to pony up for Cometics if I don't have to. Everything's been pretty low-buck up to this point.

G.M. used to stack steel shim head gaskets on the 409's in 1962 to get compression down to one that would like pump gas...........lowered it to 11.5 - 1 as I recall.
Back when Fred Flintstone moved his car through the courtesy fo his two feet.
If I was building a Hemi , I don't know that 250.00 for a set of head gaskets would be unexpected.
I'm all for saving money , but using a bandaid to fix something critical just seems wrong.

I am kind of confused by the question/answers. Doesn't this all revolve around the stroke, rod length, and piston CD along with desired compression? You can get thicker cometic to compensate if you need. But have seen blocks decked that much that have been used in race motors and street motors. Ideally you rather have thin gasket and thick block, but you can't change that now.