69 N.O.X. RATT

I am considering milling my heads to increase compression a bit. It is going to be a pain in the butt becasue of piston fit problems, but none the less I am considering it.

I have 113 cc chambers, how much can I mill them with out messing things up. If neccasary I will mill the intake as well.

How much compression can be gained ?

GregP

If they are aftermarket heads you can usually find a spec for cc per x.xxx" of surface cut. At 113cc you must have BBC heads. Borrowing from the Airflow Research site for their BBC heads, they list .005"/cc for flat milling, so a .030 cut would be 6cc. I know that the Pro Action heads site also gives milling data. A few cc's can make quite a CR difference, so calculate how much you need in advance.

69 N.O.X. RATT

Thanks Greg :chevy

gkull

I was looking at another site about a simular question. The real racers were all in favor of .125 angle milling. You do have to do the intake side also or the intake manifold it's self.

The plus to angle mill is better vavle angle and your not weakening the head. The quench side of the chamber is relativly thin with a water jacket above it. .060 flat mill really makes it thin. .ooo mill on the intake and .125 on the outside is better. I would consult a good racing head shop

I at one time ran angle milled iron heads. :)


[Modified by gkull, 5:26 PM 12/10/2002]

69ttop502

N.O.X. I just went through this. I have a 502 crate with JE 1cc dome pistons that with an 118cc chamber make 8.75 to 1 compression. I disassembled my short block and found the pistons to be perfect as the engine only has 7500 miles on it so I didn't want to change pistons but wanted to get my compression ideally up to 10.5 to 1. So I called Brodix and they angle machined me a set of BB+2's to an 100cc chamber. I guess angle machining is the same as angle milling only it is done before the bolt holes are cut. The problem with my motor is the piston at TDC was at least .017 below deck so my original motor was way less than 8.75 to 1. So now I need to mill the deck or else use a thinner head gasket to hit my target of 10.5 to 1. I would defer this question to the real engine experts but it seems the trend is to run small dome or flat top pistons with real small chambers a la Pro Stock. Jim (427 HotRod ) once had an angle milled and then flat milled set of heads on his old 427 that ran great so maybe he can chime in here to. Bill.

69 N.O.X. RATT

I do not want to have to use different pistons after buying custom ones from JE. I would like to possibly mill the heads a little to get back the 3 cc's I lost when we cut on the heads to get the pistons to fit. I would also like to be at 10.5 to 1