will it be safe to run 404 crower cams with compression 12:4:1...or would the pistons hit the valves?

 

compression has nothing to do with piston to valve clearance.

 

Clay the motor and check clearances.

 

computer froze, next post

 

I hope this one is sarcastic, compression (dome height) and valve lift have everything to do with p2v clearance. Ever notice how turbo pistons are dished and all motor ones with high compression have domes, some even peaks. You should measure p2v clearance with 11.5:1 and over pistons when using big cams, just to be sure.

 

No...what he's saying is that just because you have a lower CR vs a Higher CR doesn't necessarily mean that the lower CR will be safe w/ a certain cam when the higher CR won't be safe. It has everything to do with the piston design....which does contribute to CR...but just b/c a certain design has a higher CR, doesn't mean it won't be safe w/ certain cams....and vice-versa.

Any answers the OP is going to get to this question are all going to be guesses. The ONLY way to know for sure is to clay the engine.