Chris Kantarjiev writes:
> bunch of things. All of which boil down to that you can't really back-figure
> the specs (especially duration/timing/overlap) for an unknown cam: you need to
> know the "checking clearance", which basically translates to the valve lash
> that you'd set, and take it into account. (Yes, you can measure lift.
True enough! But you can figure the lobe centers, and if you know the
duration, you should be able to guess as to where the "checking
clearance should be. Yes? I should also add that I checked the lift
by removing the rockers, and using a dial indicator attached to a push
rod, to watch how far the cam pushed up on the indicator. The dial
indicator was firmly attached to the head via a magnetic base.
Speaking of checking clearance. How do the cam manufactures come up
with the tolerances for the valve lash? They seem to vary greatly,
and rarely match the stock clearances! Is this a timing issue? Or a
method of fine tuning the cam?
If you widen the gap on the valve lash, the valve has less lift, opens
later, and closes sooner. So it appears that one can do quite a bit
just playing with that. However, setting these tolerances are usually
measured cold. As the mettles expand, isn't some (or all) of that
tolerance eaten up? What's the scoop!?
> The TR6 shop manual (under Leyland) certainly took a big step down in quality
> and information from the earlier versions, but I'd be very surprised if there
> isn't a timing diagram in the engine assembly section.
I checked the Bentley manual and the Haynes, but don't have a Factory
manual. (Isn't that what the Bentley manual is supposed to be?) I'd
love to find a good cam reference.
Cheers,
-Scotty
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