Fred that's exactly right, I thought that was what I was getting across in my earliy postings. I worked at Fermi National Accelerator Lab for 27 years and did a lot of leak testing on a large variety of weldments used for ultra high vacuum applications. I've seen may cracks that wouldn't show up with helium leak testing down to ten to the minus tenth yet when the object was warmed up it opened up. Quite common and it would be especially true with the temperatures that are encountered in an internal combustion engine.
That's true Roy, I've been taking a reading on the plugs about every 1000 miles for the past 6000 miles looking for just that symptom. That will build up a heavy tan calcified deposit from the glycol.
Cleon, I installed a new oil feed tube when I did the valve job and check it very closely quite often. And I learned early on that the
GM inline heads were prone to cracks in the combustion chambers as I noted earlier. As I said, I had to go through four heads to find one that would pass Magnaflux. In fact for those that are unfamiliar with what we're talking about, here are a couple of pictures of the area where it most often appears.
http://rides.webshots.com/photo/2331152890098611668AqSsyV Thanks for the comments guys.
Denny Graham
Sandwich, IL
