FYI, part of the problem with late B cams wearing out prematurely is the
catalytic converter, which radiates enormous heat into the block right
where the camshaft is located (especially if the carb is running too rich,
so often the problem with Z-S carbs.) This tends to bake the oil off the
cam when you shut the engine off, so every start is a virtually "dry" start
for the cam. That's yet another reason for keeping your oil good and fresh,
and your Z-S carb. and choke adjusted correctly!
Lawrie
British Sportscar Center
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> From: Chris Delling <saschris@flash.net>
> To: mgs@autox.team.net
> Subject: Cam Shaft Wear
> Date: Tuesday, December 23, 1997 11:30 AM
>
> Some info of general interest (of particular interest to rubber bumper B
> owners).
>
> I completed the removal of the camshaft in my 77B yesterday. There are
> approximately 70,000 miles on this cam. Based on the flat performance of
> the car, I sought out suggestions to correct this. I was advised by
> several sources that the cam shaft in the rubber bumper cars was prone to
> advanced wear due to a relatively soft metal being used in it's
manufacture.
>
> I just completed a mechanical inspection of the cam lobes. The stock cam
> is spec'd with 0.250" lift.
>
> Cylinder 1 2 3
> 4
> EXH IN IN EXH EXH IN
> IN EXH
>
> Lift: .265 .162 .208 .245 .205 .228
.190
> .268
>
> I can't explain the high readings for the two exhausts on 1 & 4. Perhaps
a
> bad grind. I did check them three times. Interesting the similarity
> between 1&4, and 2&3.
>
> What is not reflected in the measurements is the flat spotting, and
extreme
> pitting seen on 6 of the 8 lobes. In the extremes, the worst lobes don't
> even appear rounded any longer. By the way, the lifters look almost new,
> with no undue wear.
>
> This certainly goes a long way to explain the lost sparkle in my engine
> performance. If you are driving a late B with more than 50,000 miles on
> the clock, you may want to consider this.
>
> Regards,
>
> Chris Delling
>
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