Postby DewCatTea-Bob » Sun Nov 16, 2014 12:59 pm
[quote= Bevel bob ...
" Don't fancy mongrelizing my Mark 3 with a Monza head , "
____ Your fairly-stubborn mind-set about that is naturally understandable but,, the Monza-head has the type of in.port which you logically realize is better for desirable higher flow-velocity over the entire RPM.range, (aside-from max.volume at top-RPM, as your present head's in.port provides), and also has the additional/full-support for the valve-guide as you prefer !
__ You do indeed have a very-reasonable goal, so why-not go the route which best attains it (instead of only accepting similar but slighter-steps which are certainly less-likely to result with any noteworthy & worthwhile power-improvement in the desired rev.range direction) ?
Don't forget that the 'Diana 250' employed the very-same cyl.head & Violet-camshaft, (and well responded to the simple cam.substitution with the hop-up/Red-cam) !
__ Of-course if you were to rather swap for a Scrambler-head (with it's straight-through 28.5mm in.port), it would be a mere-step towards the desired direction,, but it's my good opinion that such an insignificant step would-not be substantial enough to cause any noteworthy difference that would make your endeavor all worthwhile.
" Interesting that you (bob) think that lower radius follower would reduce the duration,
I was thinking the opposite "
____ At times it clearly helps to properly conceive seemingly complex conceptions when ya grossly exaggerate their opposing view-points.
So think-about doing-so in the case of cam-follower contact-surface areas...
__ If the follower-radius were to be so overly large that it seemed same as an inch-long virtually flat follower-surface,, then that would have the front tip-edge of the follower encountering the cam-ramp's lifting action SOONER, and likewise, the follower's trailing tip-edge would finally come-down off-from the cam-lobe LATER,, thus causing a relatively long-duration (of rocker-arm activation).
CONVERSELY,, if the follower-radius were to be so extremely reduced that it appeared same as a worn/dull pencil-tip, then virtually only-just the center of the follower-surface would later/finally (directly) encounter the cam-lobe's lift-ramp (rather a half-inch later!), and-then (also directly) ride-off the lobe completely that much earlier (rather a half-inch sooner) ! _ And-so since the center of the follower-surface is obviously not (indirectly) supplementally-assisted, (with such a dinky radius),, then the lift-duration must thusly be rather minimized !
__ So now those two EXAGGERATED view-points should well help make it clear how reducing the follower-radius would correspondingly diminish the lift-duration of any cam's valve-timing. - (See associated pic.example comparison* now top-posted below. - [* Although not quite so vastly opposedly-exaggerated as has been described !].)
" I was thinking the opposite "
____ Perhaps you were rather directly thinking-of merely the follower's curved-shape itself alone, or amount of ark-curvature or something,, rather than the supposed 'radius' of the 360-degree circle of-which the follower's ark-area is merely just a fractional section of.
I suppose that the normally associated terminology could possibly be a source of confusion concerning the follower-radius, since that common tech.term more-so refers to a dimensional-aspect that's actually outside of the follower-surface itself. - (See supporting pic.example now posted below.)
But in any case, the 'follower-radius' should-not be confused with the degree-rate/sharpness of ark-curvature, or-else such as that could explicablely lead to "thinking the opposite".
" I could probably benefit from a bit more lift as the F1 250 cam sacrificed lift for duration. "
____ I believe I've covered this with you once before this past year.
Both G&W.cams have plenty of 'lift' -(near 10 & 8.5mm), and are virtually the same in that regard ! _ And that has the in.lift 1mm higher than that of the already hot Gray/M1.cam !
So there's really been no 'sacrifice'.
__ I've found that the small differences in lift pretty-much make no notably-measurable difference in performance.
But if you think it's worth-it anyhow, have you ever yet approached Eldert about the extra-hot M1-like camshafts that he's supposed to have ordered manufactured ?
Hopeful-Cheers,
DCT-Bob
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PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
