"Dan Neuman @SMTP@Exchange" wrote:
>
> Hello All,
> Could someone please explain to me what exactly is meant when
> a cam is reground?? I understand that the lobes on the cam control how
the
> valves are opened. Isn't the faces of the lobes some sort of treated
metal
> so that they can stand up to the punishment?? IF you regrind them dont
you
> remove this layer?? If you grind down the lobes won't that change how
the
> valves are opened??
The cam may be reground to restore it after it has been damaged (like by
not having the proper lash adjustment or due to lack of oil flow).
Since you are removing metal from the surface of the cam lobes, you
can't get the original profile back perfectly.
Often, the cam is reground to change the total lift and the timing
between the intake and exhaust valves. This is usually done to improve
performance at higher RPMs. It usually requires some modifications to
the rest of the valve gear. There is a good write-up in the Bob Sharp
Manual for the 2000 OHC.
The surface of the cam is usually heat treated to improve the hardness
of the contact area. Untreated, the lobes would wear away in a very
short time. On most street cams, this is accomplished by heating a very
thin layer on the surface of the cam with an extremely hot flame. The
thin hot surface layer then cools at an incredible rate due to
conductive heat transfer to the deeper bulk of cold steel. This locks
the surface layer into an very hard composition of steel that can resist
the wear of sliding on another steel surface. The thin surface layer is
hard but also very brittle, so you can't treat the entire cam this way
or it would crack during use.
Sometimes race cams are nitrided to give the entire cam surface a very
hard and tough surface layer. This is a chemical modification of the
surface layer that accomplishes the same function as flame hardening.
> I don't remember who was telling me this..maybe it was a
supplier??
> But this person was saying that he had a profile to regrind a solex cam
to
> make more power thru out the rev range, especially down low. How is a
> cam reground to do this???
It isn't easy to get both good low RPM performance and, at the same
time, good high RPM performance. Usually the objective is to increase
the time that the intake valve is fully open so that more air/fuel flows
into the cylinder. Faster and higher lifts usually result in much
faster wear on the valve train parts. There is no free lunch.
> Is there a cam FAQ that I am missing??
Not that I know about.
>
> Thanks,
> DAniel 69 2000
> SF CA
Rick Chianese
SRL311-14035
Orlando, FL - Sunny and 85F
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