I am helping my buddy change a cam in his car. He is going ahead and have his heads cleaned up and milled a little to help increase compression. We were wondering about valve clearance milled at .20 with the impala gaskets. He will be running a .503 .510 with 1.6's. I am pretty sure this will be ok. My ? is what compression will this give him and is it enough to bother with. oh yea this is a stock bottom end. What would you recommend

Thanks in advance

 

You meant .020 right?
.2 is a little better than 3/16 of an inch.

Milling the heads .020 won't cause a clearance problem but it wouldn't hurt to check either. A change to 1.6's and a .020 deck may require a valvetrain geometry correction (pushrod length change) but you'll have to get everything together and check it out.
As for compression, .020 is about 3ccs which gains you ~.4 point in compression. The .029 Impy gasket gains you another ~.2 points over using the stock gasket.

HTH

-Mindgame

 

I agree with Miondgane, it never hurts to check but from what I have seen, they have ALOT of P/V clearance and even milled .030 and GM 847 cam has plenty of clearance on a stock bottom end.

NightTrain66

 

oops, I meant "Mindgame".