RB Eldebrock heads/shave?

[Sport]

I have just bought a set of RPM heads and they look great! I got the closed chamber version but they are still at 84 cc. If I install them on my engine at that cc, and use the thick ,recommended coomposit gasket I will end up with about 9to1 comp: witch is not recommended with aluminum heads.With my flat tops sitting in the hole .075 I calculate that I would want amax of 74 cc to a preferable 70 cc chamber. I really dont want to cut my new heads anymore than .050 if I dont have to.Has any one already been here and done this.Does any one know how many cc,s about .040 or .050 will get me.Thanks for any input.Sport!

[DusterDave]

I had my RB Edelbrocks milled .050. The heads are advertised to have 84cc chambers, but I've heard from a few sources that their heads actually checked out to be 82cc. Assume 1 cc reduction for every .005 material removal. So, with a .050 cut, you'll end up with 72 to 74cc chambers.

You could use new pistons, and here's why. No matter how much material you remove, you will not reap the benefits of a good quench area. To get a good quench, you want no more than .060 from the piston top to the flat part of the chamber. The closer, the better. Your quench distance is over.110, assuming a .039 gasket thickness. In comparison, using flat tops sitting at zero deck, the quench distance will be equal to the thickness of the head gasket, which is .039 typically. BTW, with this arrangement and the aforementioned milled heads, my compression ratio is 11.66:1, assuming the chambers were 82cc to begin with.

[Sport]

Thanks Dave ,This is the information I was looking for. I know what I need, but I didnt want to go to far .My next engine wont have the pistons .075 in the hole. I was worried about going to far with the shave job. I want these heads to be useable with a variety of my engines combos, and I also want the quench at the .40 to.50. thanks Sport!!

[451 Jim]

I have the Edelbrock big block Performer RPM aluminum heads. I milled them 0.050" and then measured the chambers at 72cc. I did not measure them before milling.

Another guy measured 82cc before, and 74cc after milling 0.040" That is 0.005" per cc. If mine were 82cc before, then my 72cc at 0.050" matches 0.005" per cc.

A third guy measured his out of the box at 84cc. He did not mill them.

It seems some are 82cc and some are 84cc.

I also milled 0.060" off the intake side of the heads after removing 0.050" from the head gasket side. This kept my intake manifold fitting well.

[WS23]

My measurements are dead on with 451Jim. However I did measure ahead of time & they were 84cc.