The cams are bundled with springs because special springs are required for
both high RPM operation and for high lift cam lobes. The retainers are
matched to the springs.
It seems obvious that a "bespoke" cam is going to be more expensive than a
mass-manufactured pattern -- exactly how much more expensive is really a
matter of what the market will bear (and apparently it will bear quite a
lot). But remember, you are paying for the vendor's development costs and
expertise (although in the case of MGB cam grinds one might reasonably
suspect that development reached a plateau several decades ago).
But really, one might ask why you are set upon one of these "performance"
cams, when (if you'll pardon my saying so) you don't seem to know much about
them. I would suspect (or, hope might be a better word) that at least some
of these products might have notably different characteristics. At the very
least, some would be optimized for high rpm operation, others would strive
to increase mid-range torque, and others might focus on low-end grunt.
Without the benefit of variable valve timing technology, you can't expect a
cam to deliver more than one of these improvements -- it's all a big
compromise. It's not like there is some kind of magic formula for cams that
was recently discovered and can improve performance across the board
compared to the original equipment. Anytime you add performance at one end
of the RPM range, you are taking something away elsewhere -- it's all a big
compromise (to be fair, modern dual-pattern cam designs can have some net
benefits -- I'm not sure if this technology has reached LBCs yet).
Unlike the advertising I see for American V8 hot-rod cams, those targeted at
British car owners seem loath to reveal any sort of specs. The first thing
I'd do is try to get a cam card for each of these products, and compare them
on paper. Then I might talk to a knowledgeable engine builder to see which
might suit my intended purposes.
One also has to keep in mind that the engine is a system -- you may not reap
all of your expected performance without upgrading other components
(ignition, valves, weight of rotating assembly). Anyway, lots to think
about...
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires
on 9/27/11 5:41 PM, jevans at mydb3.com at jevans at mydb3.com wrote:
> Listers - Help! My engine rebuild project (1977 MGB) has stalled for lack
> of a camshaft. Anyone out there with an unused: Crane 342-0010, Moss
> 222-270, Kent 714, Piper BBP270, or APT VP11 - please contact me off list.
> Also, I wonder if any of the gurus on this list can educate a dumbo like
> me as to why a new stock grind MGB camshaft retails for under $200 while
> the mild performance grind units are over $400? Maybe the grinding stones
> are special for these units? And why are they bundled with springs,
> retainers, etc which are not demanded for stock grinds? And, for that
> matter, why is an 8 lobe MGB camshaft priced at over twice the cost of a
> 16 lobe American V8 unit? Any sensible answers to these questions would
> be highly appreciated.
> Jim Evans, Chicago
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