Open chamber head CC ??

[mattsinger]

Is there a general ballpark as to how much milling a head will reduce the chamber? I am using a set of 345 heads on a 71 383....and since the heads will be my next step after the shortblock is back together....I'm trying to start planning. I need to order up a CC kit to check where they are now....but figured there must be a general rule once I fugure how much I might need to reduce them.

thanks
Matt

 

[JohnRR]

those will be 90-92 cc , general rule is .005 for every 1 cc of chamber volums , every .010 off the deck you have to remove .0123 off the intake face so the intake fits properly.

If you are rebuilding iron heads, and it's not a oem resto or building for class racing, it would be cheaper to buy alum heads like 440source or ebrocks .

 

[mattsinger]

Thanks John...thats what I was looking for.

I agree with your comment.....but I have been slowly working on these...mild bowl work...and new valves and springs already sitting on the bench. Just need to get them in for hardened seats and guides. If I were to do it over....I probably would do the aluminum head option.

 

[IQ52]

On that head you should remove .0042" for each cc. Remember that for each .010" removed from the combustion chamber side of head, you should remove .0123" from the intake manifold side of the head. For the smaller combustion chamber heads like the 516 or the 915 you would remove .0062" per cc.

 

[mattsinger]

On that head you should remove .0042" for each cc. Remember that for each .010" removed from the combustion chamber side of head, you should remove .0123" from the intake manifold side of the head. For the smaller combustion chamber heads like the 516 or the 915 you would remove .0062" per cc.

thanks
so my first step will be to CC these heads and see what I have to start with. The 383 is .030 over with the pistons .005 down. I'd like to end up somewhere in the 9 - 9.5:1 range

 

[JohnRR]

thanks
so my first step will be to CC these heads and see what I have to start with. The 383 is .030 over with the pistons .005 down. I'd like to end up somewhere in the 9 - 9.5:1 range

You won't be cutting much off the heads then , they were 9.2ish at std bore and he heads at 90cc , pistons were .0025 in the hole . Confirm your piston in the hole , CC heads to get your head size and pick your head gasket THEN determine how much needs to be removed from each head.

You don't need to CC every chamber , they should be within .5cc of each other , do one on each head , maybe 2 one on an end and one in the middle , skip one , don't do 2 next to each other .

What pistons did you use and how much did you cut off the block ?

 

[mattsinger]

You won't be cutting much off the heads then .

What pistons did you use and how much did you cut off the block ?

thats what I am hoping for
I am using Diamond Pistons..#51907 and scat 440 length h beams. I'll be picking the block up from the machine shop tonight.....but in conversations with him, he said it didn't take much to clean it up to .005 deck.

 

[mattsinger]

The shop said they decked the block .006 to get a .005 deck