Being Flatheadless and Knuckleheadless now a days, I am working a Shovelhead with a problem. It appears I have found the cause of the leak at the front exhaust push rod tube upper seal. Leak has been there a while. I have changed from Oring type tubes to the larger type seal tubes. Leak on this 1 seal persists.
I have the push rods out and was looking closely at the way the tubes seal against the rocker box. I have stumbled across a problem. The front exhaust tube seat in the rocker box itself is machined at the wrong angle. This causes the tube to not seal against the rocker box all the way around it. If you hold the tube in the rocker box without a seal to where the tube is seated against the box, it doesn't point toward the tappet block. Pointing the tube toward the tappet block causes the upper seat to not sit against the rocker box all the way around. It is offset by at least 3/4 of the tube itself. The rest of them seem fine and are fairly closely aligned, pointed toward the tappet block seats. Doing the same thing from the tappet block side seems fairly accurate on all 4 tubes.
Has anyone ever ran into this before? If so are there any suggestions to machine the seat straight? It looks like it would need an end cutter measuring 15/16"
I know some of you guys come up with some pretty imaginative machining techniques ant this may take that.
Rocker boxes are 1979.