vettenuts

iTrader: (4)

Rebuilding my stock heads over the winter and while systematically cleaning each port I came upon this. I wanted to get any other input on this if anyone has seen something like this before. The photo makes it look worse than it is, but you can catch a fingernail on it. It appears to be only cylinder #2, maybe a tad on cylinder #4 intake as well but not as bad. Haven't looked at the other head yet.

I put the valve against the ring on the seat, the ring is just at the outer diameter of the valve so it is not the seating surface. No apparent damage to the valve.

Comments/input???

Greg Good

Lap it in and then see what the valve to seat contact looks like. If it doesn't lap in well then have it bumped with a stone at a machine shop. Actually, a good rebuild would include a professional competition valve job.

Richard@WCCH

iTrader: (3)

Looks like light detonation to me. We've seen the same thing on a number of heads with powdered metal seats including Ford mod motor heads. Feathering the seat ring edge is a common sight. Sometimes there are chunks missing from the intake seat ring when the detonation is severe. Your seats appear to be very useable and I would second what Greg mentioned about remachining the seats to regain concentricity and maintain a positive seal.


Good luck,

Richard

vettenuts

iTrader: (4)

It is the aluminum/seat interface. I spent some time on it last night and used some fine emory to smooth it back out finishing it with 2000 grit. I also set the valve in place and the region in the photo is about 1/16" outside the valve radius so the seat should lap well.

However, the valve seat edge where it meets the aluminum is not perfect like on the others. Should this be dressed by a shop or will it be OK with lapping the valves back in so they seal well?

The car from the factory did have some detonation at 4,200 RPM, it was very evident on the stock dyno I did and you could hear it as well