Thread: Building a ZZ430 clone. Question about quench, compression ratio, etc.

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Originally Posted by v6underpressure

What would be the difference between your suggested 14096405 and 10105117??? They both have graphite and stainless fire rings. Not to mention they both have a compressed thickness of 0.028". This is a ZZ4 crate engine and I don't have the tooling to cut the decks etc. so I'm only doing the top end. So you are also saying that a 0.028" gasket will work with my combination?

10105117 has a 4.000" bore and the edges of the gasket could overhang into the cylinder bore on an overbored block, creating a "glow plug" that could fire incoming mixture before the spark plug gets a chance to do its business. Pre-ignition equals detonation. 14096405 has a 4.100" bore, so the edges of it are back away from the fire a little.
Either gasket, although not ideal, will work with aluminum heads and prevent the fretting of the aluminum material that occurs with a steel shim gasket.

I would further comment that every good engine build should include claying the piston crowns for valve to piston clearance checks. Actually, there should be 3 to 4 trial assemblies to check different clearances before anything is permanently bolted together.

Next time you plan an engine build, begin with the stack of parts you will use and cut the block decks to that dimension. Then you can use the proper gasket for aluminum heads (Fel-Pro 1003) and have a 0.041" squish. For instance, building a 383, crank radius is 1.875", rod is 6.000" and piston compression height is 1.125". Add these 3 values together and find 9.000". Cut the decks to 9.000" and like I said, use the 1003 gasket. Everybody's happy.

Most of the younguns on these forums seem to go bananas at the thoughts of cutting the block decks. The block is not sacred. It is there for you to alter to your needs and decking costs only about $150, so it's not the end of the world as far as your finances go.

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