Moparts Tech Archive

Big Block

Edelbrock BB Head cc after milling

I just cc'ed my Edelbrock Performer RPM aluminum heads for my big block. After I had them milled 0.050", they came out 72cc. I had expected 74-75cc. This will put my 451 at 11.8 CR instead of 11.4, so that is good news. Below is a pic of the chambers before milling. After milling the ruler dimension was 3.25"

beforemilling8084.jpg - 38150 Bytes

The numbers in the picture, 80 & 84, are numbers stamped on the heads. I think they are a QA stamp from Edelbrock and I use them for identification. These are the #6092 heads with a spec. of 84cc from Edelbrock.

I did not have the heads cc'd before milling. I don't own the equipment, I used one of a precious few favors to borrow it. The variation was 72.0 to 72.3 cc's. The burrette (sp?) is graduated in 0.1 cc's.

Does anyone else have milling cc's on these heads to share?

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i just milled the test heads yesterday.
i checked one cylinder from each head, one was 81.8, the other 82.0, BEFORE milling, and after polishing. i suspect this is why Jims heads are a little smaller than what he expected. i milled .040 off the heads, and they are now a nominal 74cc's.

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I cc'd my stock E-brocks and they all came in between 83.8 and 84.1 which does not seem to bad Q/C wise. My comp cal'c to 10.55-1 and I was satisfied with that for a road machine.

Some of the early estimates from Edelbrock were 0.005"-0.006" per cc. Fast68Plymouth's before and after results show 0.005" per cc. If mine were 82cc like the test heads he has, then that matches my 72cc after 0.050" removed. It sounds like some heads are 82cc and some 84cc from Edelbrock.

I did a before and after check of my intake manifold. My 400 block was 9.977" deck height (9.980" spec). With the uncut Edelbrock heads, the M1 single plane intake fit perfect. After milling 0.050" from the cylinder face of the heads, and 0.060" from the intake side of the heads, the manifold still fit good on the same block. So 0.012" on the intake for every 0.010" on the cylinder side seems to work.

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