Compression calculation

[darren509]

I have seen the formula on this chat before on how to calculate it but Im still confused. My edel heads say they have a 5/8" deck and when Im looking at piston choices they say the ratio is based on a .010" deck. Now, how do I add my head deck height into this, do I add that to the deck height between the top of piston and the block's deck, then add in gasket thickness and bore + stroke ?

[ehostler]

http://www.kb-silvolite.com/temp/calc.php

Install the piston and measure their depth at TDC and then use the proper calc. Unless you have had your block deck to factory specs, this is the only way to know for definate.

[darren509]

Im trying to find out before I buy a wrong piston combo for the stroker. My main concern is to how much comp. I can run on 91 octane with my edel heads with out detonation. No mods to the head and using their recomended head gasket. Im thinking that 11-0-1 would be stout enough for the street and strip. That is another topic though Come to think of it my block is at factory specs...

[hedgehog]

The 5/8" refers to the thickness of the deck surface of the head.

[ehostler]

11.5:1 is your max on the expensive stuff, with un-modified EB heads. At a minimum, I would have the chambers polished. It prevents hot spots and will allow you to get to about 12:1 on 91 octane.

Get with Don and you can set you up with a better head gasket that is actually cut to your bore.

When you say that your block is factory specs, are you saying that the decks have been machined to factory spec, or are you saying the decks have never been touched.

If the decks have never been touch, they are not factory spec. The production decks were a little taller than spec.

You really need to know the height of the piston from the center of the pin. Then determine where that will place the piston, in your cylinder at TDC. Then you can determine how much volume is left above the piston.

[darren509]

The block has never been machined. What is the factory spec on the block height. Its a 73 block if that helps. Also when I take it in for machining what do I tell them to cut it to ?

[darren509]

Looking at Probeindustries.com the part # 13746-30 it says , " comp/HT 1.476 Is this what Im looking for or do I have to actually measure it when I get them ?