Valves Hitting Pistons!!!!!?????

[jmm]

First off this is Dans66Stevens. For some reason I can't log in my own name.... :hammerhea
I pulled the heads off my motor the other night. I have a cracked square port head I needed to replace. After removing the heads I noticed on one side these little marks in the valve reliefs. It is a very small polished spot about a 1/2 inch long. It looks like a spot that was polished on each piston. Im sure the valves are just touching the pistons.
My machine shop guy who is a very very well known local engine builder says take a die grinder and a vacum cleaner and just open up the relief a little bit. Im sure .020 or so would be enough. Or should I just buy a set of thicker head gaskets. Im thinking of doing both....

[Norseman]

First off this is Dans66Stevens. For some reason I can't log in my own name.... :hammerhea
I pulled the heads off my motor the other night. I have a cracked square port head I needed to replace. After removing the heads I noticed on one side these little marks in the valve reliefs. It is a very small polished spot about a 1/2 inch long. It looks like a spot that was polished on each piston. Im sure the valves are just touching the pistons.
My machine shop guy who is a very very well known local engine builder says take a die grinder and a vacum cleaner and just open up the relief a little bit. Im sure .020 or so would be enough. Or should I just buy a set of thicker head gaskets. Im thinking of doing both....
If it was me I'd make sure the springs are what they should be, and then very carefully take the die grinder to the pistons. Make sure you vacuum up all the alum chips, and smooth everything out real well.
If you increase the gaskets your going to increase the quench area, and drop compression. Unless the compression is high already, I'd go with the grinder.
Bob

[HOSS]

I agree. Make sure valve springs match cam. Next, are these the right pushrods/rockers? I might even go with an adjustable pushrod before I started grinding my piston. I would only recommend a machine shop (thats capable) do this. Expansion and carbon has to be considerred.

[Cas]

I'm assuming the relief's don't have a big enough radius?
I went through the same thing with mine. I had the rec port sized valves put in my 781's and found during assembly the radius of the reliefs weren't big enough. I thought about the die grinder thing for a few minutes but chose to mark the pistons and take them in. The machine shop did an awesome job, next day service all for $80.00. Was worth the peace of mind to me.

[jmm]

relief's don't have a big enough radius....This is exactly the problem. Im talking a very small polished spot the size of a pencil eraser. The valves are fine. Its only on one side. I will cc the chambers so that they match.