>Not all heads ( L-series for one ) have removible cam towers, therefore
>to correct for the top of the head being wraped you would need to
>aline-bore the cam journals.
>We are lucky with the design of our U20, the cam towers can be removed.
>Sometime its necessary to the the cam journals aline-bored on the U20.
Not true, Phil. You can remove the cam towers on L-motors. It was
stressed in in the HP "How to Modify..." book, first published in '74/'75
that you shouldn't remove them, but that and a number of other thing in
the book are incorrect. In fact a popular mod (almost required) on hot
L-4's is to use the cam towers and (shortened) cam oiling spray bar from
early L-6's. The trick to getting L-series cam towers back on right is to
snug them down while rotating the cam so that it doesn't bind. Of course
if the head is warped this may not be possible without truing the head
surface and the pads the towers sit on.
There are shims, commonly called head savers, that are designed to move
the cam back and take up chain slack caused by excessive head milling.
These go between the head and the cam towers. The head savers move the
cam back up in relation to the crank. Align boring the cam towers usually
introduces too much clearance since the cam rides directly in the tower
(no bearing inserts).
FWIW, Ron
________________
Ronnie Day
rday@airmail.net
Dallas/Ft. Worth
'71 510 2-dr (Prepared class autocrosser)
'73 510 2-dr (Street Toy)
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