List,
We have been discussing cam profiles recently. I am preparing to assemble my
U20 engine and have questions regarding rocker arm geometry. My head has been
milled about .010. The deck was milled about .005. My B cam was reground to
remove surface rust but only .003 was removed off of the profile. The rockers
were also resurfaced. This puts the cam .015 closer to the crank and also
leaves a few thousandths extra clearance between the rockers and cam. To keep
everything correct I have read I should shim the towers by the amount milled
and add thickness to the rocker arm buttons by the amount milled, plus the
thickness removed from the cam and rockers, plus an extra .025-.040 to help
center the pattern on the rocker surface.
Does this sound like I am on the right track? If I have milled less than .020
total do I really need to shim the towers? I have not checked the pattern on
the rocker surfaces yet but am under the impression that I should at least buy
thicker buttons to center the pattern on the pad.
Are buttons available in thicker increments or will I have to have some made??
Also, does anyone offer an adjustable cam gear to advance the cam timing as
things wear? Is this worth the expense? Any comments or suggestions would be
appreciated.
John Over
68 2000
rebuild with old Solex underway
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