Compression

SSDA67 said
On higher RPM engines you need more than .045 at times.I had a .060 over 440 with a set of Arias domed pistons and 516 Heads that had .100 milled off of.I had to put a .124 gasket on to keep the valves from hitting with my .650 Flat Tappet cam with 290o Duration at .050.
Now on the HEMI's it is a complete different Geometry to do to keep the valves from Over-Lap collision.
I have had a 501 C.I. motor with 62CC INDY Cyl Heads with a .692 Roller with 286o Duration at .050 and had the piston .020 out of the hole and a .042 gasket leaving .022 piston to head and .030 piston to valve clearance.I broke a rod in this motor and later come to the conclusion that the $800/set rod broke because of hitting the valve(impressions of valve on the pistons)on the piston.

Piston to valve clearance is an entirely different story!! Especially when your talking about domed pistons. Good thing you brought this up, as P to V clearance must be checked while mocking up an engine regardless of piston to head clearance. According to Crane Cams (and a lot of other sources), you must have a minimum of .100" clearance on the intake and .120" on the exhaust. When I say "minimum", I mean that everything else is in perfect condition, no weird valvetrain harmonics, perfectly set up valve springs, no rocker to retainer interference, no retainer to guide interference, etc. The last LA engine I built had a relatively mild cam and flat tops and speced out to .142 and .155. Thirty thousandths with a big *** cam? Ouch!!! Rehr Morrison also recommends .050 between the outside radius of the valve head and the inner edge of the valve relief. By the way, .022" P to H clearance is too tight for a flat top piston (what we were alluding to), not to mention a domed piston. Sorry to hear about your Hemi though, :sad: Must have made one hell of a racket before it let loose.

Rumblefish360

Theres 3.5 million in my county and it just gets denser towards the city.

Yeah, I used to live in Chicago, so I know what you mean. I left for Colorado 12 years ago and never looked back. I do miss the food, the horsepower, friends and family, but visit once a year! Just couldn't stand know-nothing politicians telling me that I couldn't defend my family, myself or my property. :angry4: Sorry! Didn't mean to make this a political thread! :brave: