I went t the machine shop yesterday to look at the head. They had removed the valves, and hot tanked so that it was bare metal clean. I could see that the area of the combustion chamber between the valves looked like it had been hit with a rose bud until cherry red and became very much blue on all six of them. I also noticed that there was no combustion chamber depression at all in the area of the intake valve.
I do not know how many times this head has been machined or if someone shaved a bunch off to increase compression ratio, prior to when this machine shop has worked on it. They have shaved it twice. Once, when they did the original total rebuild 20,000 miles ago, and a second time after I through a connecting rod 2,000-3,000 miles ago.
I am wondering if the lack of any depression in the combustion chamber near the intake valve has caused the problem of that area to cook, as well as cooking the valves.
I do have two 1954 heads (913) which I believe are unmolested and there is a significant depression near the intake valve which my '56 (848) head is lacking.
I am going to take those to the machine shop tomorrow so that he can measure the height of these to compare to the height of the '56 head to determine how much has been removed from it over the years.
I will likely just have him (not his low paid flunky) rebuild the best of the two '54 heads.
I trust this machine shop, but help is hard to find these days, let alone good help.
Last edited by 52Carl; 06/02/2023 12:14 AM.
