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Edelbrock E Street heads - how much to mill to reduce volume by (X) cc ?

Meep-Meep

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Building a low block 426 for a guy and so far the compression is calculated to be ~9.4:1. .060" over (4.31") with 3.75" stroke and nearly zero deck piston with valve reliefs, small bore chamfer, comp gasket. I'm trying to target about 9.8-10:1 to keep it CA swill friendly with aluminum. If iron I'd be done. Does anyone have any correlation in milling amount vs chamber volume? If I recall these are about the volume of 906 heads (high 80's) but I don't have my notes in front of me. I can get .020" Cometics but would rather chop the heads and use easily obtainable FelPro gaskets. I can get the amount to cut the intake side from the DC book. Thanks.
 
according to the wallace calculator going from 9.4/10 with 3.75 stroke is .024 removed!your going to need to check valve relief clearance before you do anything!
 
according to the wallace calculator going from 9.4/10 with 3.75 stroke is .024 removed!your going to need to check valve relief clearance before you do anything!

Not so fast... That would be .024 off the deck height which is the full cylinder diameter... The chamber on a closed chamber head is roughly 50% of the cylinder diameter & as you cut the head that becomes less....
 
E Street comes in two flavors

84cc - Straight Plug

75cc - Angle Plug
 
"Roughly" 1 cc for every .006" milled.
My 84cc RPM's worked out very close to that. It's been awhile but the ones tested, started between 84-85 and ended up around 79 if that helps..
 
"Roughly" 1 cc for every .006" milled.
My 84cc RPM's worked out very close to that. It's been awhile but the ones tested, started between 84-85 and ended up around 79 if that helps..
That's the info I was looking for and the same number I got from another source. Good to know you proved the rule of thumb.
 
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