found to be in good, rebuildable condition. However, before machine
work could begin to install hardened intake and exhaust seats for
unleaded fuel, as well as new valves and springs, the pressed-in valve
guides needed to be removed.
Before the valve guides were removed with a punch, they were
inspected. There was something suspicious about several of the guides.
The outside of them was cracked or broken away, though the inside of
these guides remained solid. It was determined that a previous machinist
had drilled out the center of the original guides and inserted new guides
in the center of the old valve guides, perhaps when the heads were
rebuilt about 6,000 miles ago. The original guides became thin and
began cracking away, leaving a mess and certainly metal parts floating
around the crankcase.
After the original valve guides were punched out,
new valve guides were pressed into place.Once the guides were punched out, Herman immediately test-fit the
new guides to verify their size and fit in the head. One of the cavities in
which the valve guide was to be pressed was found to be .005 inch too
large. As a result, an oversize valve guide that retained an internal
diameter at the factory specification was special-ordered. With Metal
Crafters’ extensive machining equipment, the shop could also machine
an existing valve guide to fit this engine application, if necessary.