Re: Stag cam shafts MKI v. MKII

[Glenn Merrell <gmerrel@domain.elided>]

Hello Larry,
	The parts catalogs indicate that there was only one camshaft each for left and
right, PN 215381 and 215382.

BUT, the wear you indicate is in the aluminum journal, not on the steel
camshaft. This is a typical problem of aluminum heads with overhead cams that do
not use a bearing shell.  If you use an outside micrometer to check the camshaft
bearing surfaces, I'll bet you will find that they are all about the same
diameter, within a couple of thousands.  Normal fix is to toss the head when the
journals are worn. Typical (proper) fix is for a head in this condition is for a
machine shop to do the following if not replacing the whole head:
-mill the head surface (test # one is if the head has been milled before, can it
be milled again, or does it even need to be milled again?);
-torque the head to a flat surface (this gets the head flat and cam journals in
proper alignment for line boring), called a torque plate;
-line bore the camshaft journals;
-fit bearing shells to the machined journals;
-machine the camshaft bearing surfaces to match the new bearing diameters;
-fit oversize plugs in front and rear cam seal positions.
-why not polish and port, 3 angle grind the seats while you are at it?

The good news is that this is a better system than using just the base aluminum
in the head as a cam bearing, true if the oil is kept renewed that it is usually
a non problem.  Bad news is it will cost you some moo-la!  There comes a point
where the cost of a replacement head is less than getting an old one fixed.

I'd contact the person(s) whom did your engine and head work and go back to them
with your results on finding a crudded up oil gallery causing the damage to the
cam journal.  Maybe you can get some remedy that way to do a proper fix for
free.

There are companies that make hardened sleeves that can be attached to the
bearing surfaces of the cam to increase the diameter, then the head journals are
line bored to match, similar to the popular fix for front and rear crankshaft
seal surfaces.  I'd go with the bearing shells, or just buy a new replacement
head.  Maybe you can go for the new Millennium heads?

In My Humble Amateur Opinion, Yours for Speculation

Regards,
Glenn  Merrell
Triumph Stag Register USA VP
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