I know that there is only one way to find out but is anyone running a 350 with .125 dome pistons, 58cc heads and rouhly .525 lift cam with roughly 250 dur.? If so could you tell me if you have had any clearance issues?

Thanks

 

Closest I've come recently was putting a set of Vortecs (stock 1.94/1.50 valves on a 350 with .200" domed Keith Black hypereutectic pistons. Cam was a flat tappet solid lifter with 252/258 duration and about .520 lift on both valves. Cleared by a mile. KBs have very large valve reliefs.

I also did the same thing with some Federal Mogul pistons with a .250" dome and they also cleared, but not by as much.

It's not really the dome that's a problem (just gotta make sure it clears the spark plug and chamber walls) it more the size and shape of the valve reliefs that makes the most difference, along with the actual AS-INSALLED specs on the cam, obviously.

You should shoot for a MINIMUM clearance of .080" on the intake, .100" on the exhaust if you expect it to live a long and happy life.

Also, the diameter of the valves can come into play. You have to make sure it's got enough RADIAL clearance around the edge of the valve without coming too close to the valve relief walls in the piston. 1.94/1.50 valves or smaller will almost never cause a problem. When you get up to 2.02/1.60 or larger valves you better check to be sure or cross your fingers and say a few prayers before you wind it up to high RPMs the first time.

 

Thanks Damon for the heads up!!

Well anyway it's all buttoned up and clears with no problem!

I used some of my daughters play doh and spread across the piston every bit of an 1/8 of an inch and not even a hint of valve touched it.....So it's all good and I'm happy as hell!!!lol:lala: