Postby DewCatTea-Bob » Sun Jan 04, 2015 7:02 pm
[quote= Crazygreg ...
" I have a few picture of it somewhere i took of it straight on, "
____ For the easiest way to compare & recognize the various std.Duke-cams, it's best to align the intended pic.shot down the center-hole of the shaft from the left-side, thus-then showing the profile of the ex.lobe at the most perfect view-angle possible.
" the lobes are quite fatter than regular monza cam, "
____ Indeed, as both the Mark-III & Mach-I cams obviously are, compared to the Monza & Scrambler cams !
" but not as fat as another unknown cam that i have too "
____ I gather you're referring to your "left" cam. (?) _ In which case, that-one appears to be an aftermarket camshaft.
" I attached the only picture i have handy, its the one on the right... the left one has even more lift, "
____ Your submitted picture seems to have been posted cocked-over somehow, and-so the particular camshaft that you are most-so referring-to is a Ducati-factory std.production-cam which is actually viewed rather on the upper-side of your posted-pic, (instead of on the "right" as you indicate).
" i know the picture is less than ideal, but i will post the other ones when i find them "
____ They ought-to be nearly as interesting, and-so still worth seeing.
If you also attempt to refer-to anything in particular seen within them, as well,, then please be sure to check that they've been posted in the same orientation that you've expected them to be viewed at.
" The engine was becoming noisier around the head, i think it might have been mostly the exaust valve rubbing on the piston... "
____ That supposed abnormal-contact really shouldn't be able to occur within an engine that can still seemingly run properly. _ Cuz in order for ex.valve-to-piston contact to occur due-to camshaft retardation,, the camshaft would then have-to be retarded more than a damaged (but still functional) w.key could possibly allow, and also the engine's performance would then notably suffer as well (when the camshaft may happen to be so extensively retarded far enough so as to allow such disfunctional contact) !
" it felt like the retarding of the cam improved the low end performance (acceleration especially) "
____ The relatively small amount of cam-retardation allowed by a halfway-split/damaged w.key, really shouldn't make such a greatly noticeable difference in performance. _ So I'd rather choose to suspect some other cause for the notable-difference in low-end performance.
" measured the values with the timing tool in place (disk on the left side),and 0.25mm clearance with 0.1 gage for intake and 0.4mm clearance 0.1mm gage for exhaust. "
____ That's indeed the correct method for reading the timing-figures according to the factory, (although I-myself believe that the true valve-timing of a cam should just take-out the inclusion of the clearance-ramps of the cam-track). _ So now realizing your new revelation, more affirmed credence can now be justifiably accredited to your stated found timing-figures, (which I'll go-over later).
" Noted the value when the 0.1mm gage started to get pinched. "
____ That you took your readings when it "started" to become zero-clearance, could possibly help explain your slightly exaggerated timing-durations (for a "Mark-3" cam). _ So you should've also taken readings with a .05mm-gauge as well, (which would've then provided a bracket-range for the actual-timing to fall within).
" Lift was roughly measured with a caliper beside the valve top, "
____ While that method could provide the actual valve-lift, it's rather difficult to obtain minutely-accurate figures which can more definitely discern the established differences between the various similar cam.models.
" i did measure the lobes diameter a while back and it was similarly close. "
____ Of-course likely so, however the actual lobe-height measurements are needed in order to more definitely identify any particular cam.model (and thusly exclude all others) !
" (a little more on the lobe measurement if i recall properly) "
____ That would stand to fair reason, as the rocker-ratio cuts about 4% of the 'lift'.
" I actually put back the bike together with these timing values, "
____ Your previously stated valve-timing figures are pretty-close to the Mach-1/Gray-cam camshaft-model, but also not too far-off from the Mark-III/Red-cam & 350Mark-3/Green&White-cam models as well.
However your found intake-lift (of over 9mm), effectively well eliminates the possibility of your foremost-presented camshaft being the Red-model !
" i will check my ignition timing again as i use a power dynamo and the timing is 9 idle to 38 @3000rpm (instead of the 21 idle to 39 @3000rpm from the workshop manual) "
____ That seemingly tends to indicate that you have a 28-degree AAU.model installed, which thusly sheds doubt on the particular model of engine you've been referring-to.
So can you elaborate on your reasoning for why you choose to believe your engine is a 1965 250Mark-3 ?
" The bike is running quite well, but still not as good as when the play was present in the bevel.. "
____ What other changes do you suppose you could've possibly also made during your related repair-work ?
" Actually the cam on the left is really strange, "
____ That's certainly likely not a Ducati-factory camshaft-model,, and it sort-of reminds me of the appearance-looks of an old 'Weber-cam', which was a top popular aftermarket cam-reprofiling company (in California, as I recall). _ However your somewhat sparsely presented pic-shot of your non-factory camshaft, seems to appear as being rather entirely 'aftermarket',, so perhaps it was wholely produced by 'Webcam' or some-other aftermarket-camshaft competitor such as 'Norris' or the like, (but it seems that such top-notch companies would include a logo-mark somewhere upon their shafts).
" the cam i'm talking about for timing value is the one on the right "
____ I've added an altered version of your pic which now shows the camshaft of your intended main topic rather viewed on the "right" side (as seemingly expected).
If you rather see your-own pic properly orientated (as you seem to have expected), and-yet see my posted version as being the one that's rotated 90-degrees off-set,, then it must be that our respective PC/web-browsers are-not in agreement as to which preset-view is the proper orientation.
__ Anyhow, now that I've had a good/close look at your picture of that cam,, considering every clue covered so-far (without any confirming dimensional-measurement details), I most suspect that that-camshaft is a 350Mk3/G&W-cam.model.
Duke-Cheers,
-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
about 9.5mm lift
about 8mm lift