440 head shave

[70gtx]

can anyone tell me how much c/r is gained by shaving .030 off stock 346 heads. and how much to shave intake side of head so the intake will still fit? Is .030 the most you can shave with stock pistons?

[DartGT66]

No, no one can tell you that without knowing your current CR. The lower the CR, the less it means; the higher the more. You should know the distance your pistons are below the deck at TDC, and measure the chamber cc's. If the heads are unmilled, they should be about 90cc. for every .010" shaved from the decks 0.0123" should be milled from the intake side in a BB. In milling the heads, the main problem is that the valve cover rail becomes so thin that you'll end up having gasket problems with heavily milled heads. Also the lifter preload changes and that has to be handled somehow; shorter pushrodds; shimmed rokershafts; adjustable valvetrain... .060" is about the max I would mill. But before any milling is done you must know what your CR is now, and what you want it to be. Mopars usually have very low CR's, and the wisest method of bringing it up is to change the pistons.

[SubLime440]

Hey DartGT66, I know I have asked a similar question, For Valve clearance w/ Hydraulic lifters couldn't you just warm up the engine (Pump Lifters Up) and then hand crank engine over, while measuring with feeler gauge underneath rocker arms and once you feel bind of valve hitting piston (carefully) use that measurement?? I am running low compression based on my compression tester... (100 - 105 psi per cyl) but I also have a 440 cuda that runs 11's with only 110 - 115 psi so I'm sure the air at 6000 ft above sea level has something to do with that!
Thanks... Just an FYI... The reason I want to shave heads is I'm going from 915 closed chamber to the 452 open chambers ( Bigger valves and ported) and will lose compression...

[70gtx]

thanks dartgt66 you told me the mill specs. i needed to know.i thought maybe someone knew about how much c/r would gain for every .010 shaved. i know i need to get it apart to check c/r.can anyone tell me what minimum clearence is between piston and valve on 440 ?

[SubLime440]

I believe it's .100 if I'm not mistaken...That's spec per Mopar...I believe.

[DartGT66]

Yes, I think you could do that, but how reliable that figure will be is another question. I guess, if you can warm the engine up, you don't have any valve to piston clearance problems? The .100" is a pretty safe clearance, you can go to smaller than that, but then you really have to keep an eye on things, mainly spring pressures. I have done the milling thing myself, but do not recommend it except for CR fine tuning. The last time I milled over .080" from SB heads, and previously have milled .090" out of a 440 deck. Both worked OK, with the SB I had some initial problems with the valve cover gasket seal since the rail was so thin that it liked to 'cut' the gasket. Just had to leave the bolts a little looser to cure it. In the 440 I didn't have to mill the intake sides since I already used intake spacers.