1968 250 MK3D rebuild - ex W/C Oil Pump

[machten]

____ It makes fair sense that a place with "Scrambler" in their name would sell the 'White' cam -(a springer-type camshaft), since 4 different scrambler-camshafts with that same color-code have been produced by Ducati !

Yes. Except for the fact that it is a DESMO cam!! (so they're not quite true to name - and there's nothing wrong with that!)

Kev

[DewCatTea-Bob]

" Except for the fact that it is a DESMO cam!! "

____ But just "White" doesn't make any sense cuz most all DESMO-cams include 'White' within their color-codes ! ... Such as: Blue&White for the 250D.cam ; Red&White for the 350D.cam ; & Grey&White for the 450D.cam !
So may as well not even mention any color at all, as state it's a "White" DESMO-cam ! _ (And I'm sure there was never any White&White-D.cam [by the factory].)


D.Cheers,
-Bob

[wcorey]

Well I'm certainly confused now... I thought B&W was stock on all 3 and R&W was like a full out race cam. The 450d cam timing specs in the 450 manual on this site are consistent with B&W as is the cam in my R/T. I'm not even familiar with grey&white...



Bill

[machten]

Well I'm certainly confused now... I thought B&W was stock on all 3 and R&W was like a full out race cam.

Me too! I thought the same as Bill above. (But I'm a babe in the woods with singles stuff)

Kev

[DewCatTea-Bob]

____ Well Duke-cams being one of my top favorite-subjects (on Duc.Singles), ya might have figured/expected that I've already covered this topic/details elsewhere (within this w.site) ! _ And it seems that you newer fellas have overlooked those thread/posts.
No matter, as I much like to dish-out the actual facts ! ...


" I thought B&W was stock on all 3 and R&W was like a full out race cam. "

____ The Blue&White-D.cam was indeed the 'stock-production' DESMO-cam for all three WideCase DESMO-model motor-sizes ! _ But actually the B&W was originally intended for just the 250-motors, as it was based on the same valve-timing & valve-lift as that of the G&W-cam for the 250F1 race-only Duke-model.
The part-number for THAT D.cam is 0609.29.010, (with the '0609' standing for '250-DESMO', [with that D.cam becoming the "std.DESMO-cam"] ) !
__ The Red&White-D.cam (with even wilder v.timing & at least 2mm higher lift), was the intended D.cam specifically produced just for the 350-DESMO model !
It's part-number is 0610.29.010, (with the '0610' standing for '350-DESMO').


" The 450d cam timing specs in the 450 manual on this site are consistent with B&W as is the cam in my R/T. "

____ This factual & sorry fact of life is due to the Italian-Gov's cost-cutting demands, so Ducati was forced to compromise and use the model of D.cam most compatible with all three engine-sizes ! _ Thus the B&W-D.cam model becoming the 'Std.DESMO-cam' !
__ It should be understandable that it would cost more to mass-produce more than just one model of D.cam, and also saving on costs would be the fact that the 350 & 450 cyl.heads would then not need to be machined differently than the 250-D.head, (in order to accept the larger-lift D.cams).


" I'm not even familiar with grey&white... "

____ The Grey&White-D.cam was the intended 450-D.cam specifically produced just for the 450-DESMO model only ! _ It's part-number is 0616.29.010, (with the '0616' standing for '450-DESMO').
This awesomely amazing D.cam has 16mm of in.lobe-lift with 14mm of ex.lobe-lift ! _ However it's valve-timing is less wild than that of the R&W.

____ I've had the information about the "Special" DESMO-cams since 1973 when John White (well known of through 'Domi Racer'), had personally told me of them being findable within the 'Special Parts' listings within the 'Price Book' then available from Berliner -(the U.S.-importer). _ After John had then educated me of how the first-four digits of the Ducati part-numbers (of Ducati-made parts), definitely stood for particular Ducati-models, and I next got my hands on the Price-Book containing the 'SPECIAL' parts available by 'special-order',, I then became like a kid in a candy-shop making note of all the way-cool special-parts which could (then) be had ! _ If only I had been so aware even sooner, I then would've been able to budget myself so as to have been able to order a whole-heck of a lot more of all those fantastically desirable goodies -('Special Parts') from that special-listing !
For instance, the first time I ordered the 'special' D.cam & rocker-arms & springs for the 350F1D,, within about a week, I received the F1D-rockers, (cam was then back-ordered), which were the type with the closing-rockers that were specially made to accept the 'rocker-return' wrap-around spring. _ But all the following times I duplicated that same parts-order, all I would receive were always the std.DSEMO-type closing-rockers... I real bummer that I didn't sooner realize that I could've so easily gotten such unique parts, before they became "discontinued"!
Fortunately, that learning-experience taught me to hold on to such parts until I received more of same, before letting any go ! _ So I still have one of each example, (that were still available back then), held-on to for my very-own personal-stock.


Happy-Cheers,
-Bob

[DewCatTea-Bob]

By: wcorey...
" For the duration numbers I just did the math from the timing specs. "

____ Okay, I now understand that you simply based your given duration-figures on the company's provided valve-timing specs, which in turn were meant to be taken at the points at which there's 1/2mm valve & seat separation. _ (Which no-doubt cuts-short the true/actual valve-timing & duration!)


" Of course you're correct in that I don't know what clearance was used in the stock specs I used but for purposes of comparison in this particular case I figured it would be too small to matter. "

____ It's no-doubt (to me) that it's actually NOT too small a difference to matter (for fair/direct comparison) ! _ As I've understood that Ducati had FAIRLY taken their valve-timing specs at the very point where the clearance-ramp's lift-rate converts/switches-over to the cam-lobe's valve-lifting rate -(the moment/point when/where the valve is able to influence any change in cylinder-pressures).
This switch-over point is often somewhat different from cam to cam and is thus mainly responsible for any differences in recommended valve-clearances from model to model.
So to note the valve-timing figures at any other point is not very fair for comparing such cam figures !


" The V2's are measured at .5mm and even if the stock ducati specs are taken .5 different one direction or the other, it moves the timing figures over some but would cause very little change in the amount of duration (I think). "

____ Back sometime around 1972 after having read an article about camshaft-timing, I wrote a letter to the cycle.mag that had done the story, asking them why Honda's engines (and other 4-stoke Jap.bike motors), produced such strong power-output with such extremely milder cam-timing than that of DUCATIs and other non-jap.bikes)... The answer I was given (or later read) was that the Japanese had standardized their figures to be taken/stated at 1mm of clearance between the valve-head & it's seat ! _ And that was the reason why the Japanese stated figures SEEMED to be so greatly different ! _ And that if ALL valve-timing figures were all done the very same way, then there would not be such noticeable differences between the Japanese-figures and that of other established manufacturers such as Ducati. _ (If I recall correctly, the same mag.article had mentioned the wild valve-timing of the 750S or 750SS.)
__ To get an idea of how much discrepancy is otherwise overlooked, if we for example expect a lobe (with 300-degrees of duration) to lift-up to it's 10mm-max.lift after 150-degrees, then that roughly averages to 1mm of lift every 15-degrees,, so it seems then that the .5mm-point could be ignoring around 8-degrees (which Ducati's given figures don't ignore). _ That is likely not an exact rule-of-thumb to go by but, it's no-doubt closer, towards the correct direction !


" There's the good reason in using lobe centers for timing, doesn't matter from what lift the timing numbers were arrived at. "

____ Unless you're also supplied with lobe-duration figures, I'm afraid I don't understand what you're actually meaning.


" The source I used for the stock B&W timing spec's was Jim Pianetta's cam data sheet, of which some are supposed to be from owners manuals and others are actual measurements. There are 4 or five B&W's listed and all but one (from '68 250 manual) are consistent. "

____ Sorry, I really didn't mean at all to question your stated figures for the Ducati-D.cam, as I was of course already quite familiar with THOSE !
__ As for the inconsistent figures taken from an owner's manual, I believe the answer to that discrepancy is due to the manual covering both the 250-Mark3 & 250-Mark3D, and also, who-ever noted the valve-timing figures simply read the figures given for the non-D w-c Mk3-camshaft !
While I believe both sets of figures are stated within a page apart, within later versions of that w-c 250-manual, I think the very-first versions had added/supplemental-pages covering the DESMO-model, which could account for someone not finding the correct figures.


" I also have the same numbers down in a file full of misc 450 specs I've compiled over the years but don't recall the source. The 450 manual on this site has the specs too but have two degrees transposed (80/82 vs 82/80 from the other source) between intake close and exhaust open. "

____ I haven't yet looked-over any other stated B&W specs but, I've long had those figures memorized since late 1968 (not too long after the first DESMO-models arrived)...
And they are:
in. = 70-BTDC to 82-ABDC
ex. = 80-BBDC to 65-ATDC


" I had read somewhere that these required modification, "

____ I also had heard somewhere that some models of the VeeTwo d.cams required modification to the D.head in order to work, and just assumed that it was for their higher-lift models, which likely require c.tunnel-widening (in order to fit-through & into the proper-position).


" I did end up putting sps cams into the 996, which have a fairly high lift with very minimal duration/overlap. Quite a transformation, brought pretty much the entire power band up with a nice big lump of torque in the middle. "

____ That was along-with retaining the same streetable exhaust-muffling, correct ?


DUKE-Cheers,
-Bob

[machten]

____ It's no-doubt (to me) that it's actually NOT too small a difference to matter (for fair/direct comparison) ! _ As I've understood that Ducati had FAIRLY taken their valve-timing specs at the very point where the clearance-ramp's lift-rate converts/switches-over to the cam-lobe's valve-lifting rate -(the moment/point when/where the valve is able to influence any change in cylinder-pressures).
This switch-over point is often somewhat different from cam to cam and is thus mainly responsible for any differences in recommended valve-clearances from model to model

So wouldn't the ramp be slow at the start, and thus not linear, there for making it easy to have significant rotational variances in duration that had little effect on actual performance?

Kev

[DewCatTea-Bob]

" So wouldn't the ramp be slow at the start, and thus not linear, there for making it easy to have significant rotational variances in duration that had little effect on actual performance? "

____ Right ! - That's exactly why Ducati provides PARTICULARLY larger clearances (than the running-clearances) for the checking of a camshaft-model's particularly-designed valve-timing !
__ I'm sorry that it seems I failed to make that understanding properly clear previously, (I guess I'll have to read what I've written and fix whatever wording allows for the failure of missing the point).
__ Ya see while the cam of course has an aggressive lift-rate intended for actually lifting the valve, the cam also has another much less aggressive lift-rate just prior that's intended to relatively gently take-up the preset clearance, and that area of the cam is referred to as the 'clearance-ramp' !
As you seem to understand, it would be pretty-much completely useless to include the clearance-ramp (along with the main-opening-lobe) in attempt to obtain the (ACTUAL) valve-timing of a cam, as including that added/extra lobe-ramp would then lead to far-out & fairly fictitious valve-timing results !
So that's the reason why Ducati supplies somewhat greater valve-clearance settings, (different for each model of camshaft !), so as to MINIMALLY just miss including the cam's clearance-ramp (during valve-timing checks) !
__ Doing it Ducati's way, (which unfortunately most often requires various different 'settings' for each cam-model), is like using a single-bullet to hit-right-on the center of the bull's-eye, whereas doing the 1mm or .5mm standardized settings method for all, is more like using a shot-gun ! - If ya 'get' what I mean, (as to how ACTUAL valve-timing OUGHT to be "FAIRLY" compared).
As those other std.methods only land ya in the 'ball-park', each time,, and that allows for 'hit & miss' comparison possibilities !


Dukaddy-DUKEs,
-Bob

[wcorey]

" There's the good reason in using lobe centers for timing, doesn't matter from what lift the timing numbers were arrived at. "

____ Unless you're also supplied with lobe-duration figures, I'm afraid I don't understand what you're actually meaning.

If you have numbers to use for setting the timing to lobe center, it then doesn't matter what the opening/closing numbers are or what lift they were taken at. You only need to find the center between open/close to set it.

This awesomely amazing D.cam has 16mm of in.lobe-lift with 14mm of ex.lobe-lift !

How sure are you of those numbers?
If that's correct it is indeed 'awesomely amazing', I've never heard of lift much past 13mm even on the most radical of the newer stuff, street or race.
Even more amazing on a 2v where the big/heavy valves would be prone to damage from the extreme acceleration caused by such lift/duration. Seems like it would pound the crap out of the whole valve train...
Then there's the clearance issues, I can see where duration would need to be short the keep the valves from hitting each other and/or the piston.

" I did end up putting sps cams into the 996, which have a fairly high lift with very minimal duration/overlap. Quite a transformation, brought pretty much the entire power band up with a nice big lump of torque in the middle. "

____ That was along-with retaining the same streetable exhaust-muffling, correct ?

Short answer, no...
You're best not to get me going on the 996, that was like a whole significant era of my life and I can expound on it endlessly. Got very deep into that one...

Exhaust is a whole topic in itself with these, there are many increments and options available. As with performance modification on most bikes, it's very misunderstood and abused, you know, 'more is better', where the reality is obviously that it needs to be matched to everything else you've done.

Stock is 45mm pipes with a combination crossover/resonator in the middle and baffled cans, the next step is 'slip on' cans still at 45mm but straight through, then 50mm cans, then (whats on mine) a step up to 50mm starting before the crossover with no resonators ('half system'). It continues on like this with 50mm right from the header/collectors ('full system') and just keeps getting bigger, up to about 60 mm. There are also hybrid systems starting at 45mm, going to 60mm, then tapering back to 45mm.

On mine the cams and exhaust were only part of it of course, there were also things like high comp pistons and many mods to the fuel inj system, etc.
All engine mods basically center around the cam choice though...



Bill

[DewCatTea-Bob]

" If you have numbers to use for setting the timing to lobe center, it then doesn't matter what the opening/closing numbers are or what lift they were taken at. You only need to find the center between open/close to set it. "

____ Oh, I get what you mean now... you were referring to an alternate means for checking that the camshaft is correctly timed to the crankshaft, (while being allowed to remain ignorant of whatever the actual valve-timing might be).


" How sure are you of those numbers? "

____ Well considering how truely incredible those lift-figures still seem to be to even myself, I can't say that I'm 100% sure TODAY, as I haven't measured either special D.cam again within the past year. ...
__ When I first laid-eyes on the Grey&White-D.cam, my eyes could not believe what it looked to be that I was seeing ! _ And when I first measured it (back in early-1974) with 1 & 2" mikes, I was then stunned & could not believe it's lift-figures, (even though just months prior, I had already been quite overly impressed with the impressively high lift-figures which I had measured on the R&W-D.cam !). _ So most every time I happened to find myself within reach of the Grey&White-D.cam (after at least a year had since past), with both micrometers handy near-by,, I'd then always (somewhat understandably) get the desire to remeasure it, once again !
However, I haven't done so since the late '80s, so I'm quite overdue for reassuring myself once again that I had done everything correctly to have gotten such incredible lift measurement results ! _ But having done it so many times, the "16 & 14mm" specs have been branded-into my memory so well that I'm sure they're right even though it's been over 3-decades since I last confirmed them.
__ The R&W lift-figures are however relatively fairly foggy in my mind, as it's been since the late '70s since I measured one of those special D-cams ... I believe that the lift-specs for that "Special" 350D.cam was either 12mm-intake & 10mm-exhaust OR 14mm-intake & 12mm-exhaust, as I recall all those particular lift-figures, concerning various 'special' Duke-cams. - (The special 450Mark-3 cam [or either the 350F1D or 250F1D) is likely the one of those stated lift-figures that's not that of the R&W.)
__ Now that this (possible)- issue has been brought to question, I'm really feeling the need to dig-up all my (NOS) DESMO-parts and check them all out once AGAIN !
__ Next, getting back to the Grey&White-D.cam...
When I noted how greatly the 450D.head would need to be modified in order to fit the over-sized 450D.cam, I then thought that perhaps some other D.cam (probably intended for some other Duke racer-engine) had mistakenly been sent-out instead,, so I later ordered a second Grey&White and received an identical D.cam packaged within another identically labeled plastic-bag. _ So then I became sure that I must have had the correct D.cam meant for the 450D.model.
I later sold my extra G&W-D.cam to a fellow DIOC-member (back in '79), who's son I gather more recently sold it to some eBay-er who then listed it on eBay (about 1.5-years ago) !
Too bad you must have missed that, as that seller confirmed it's incredible lift !


" If that's correct it is indeed 'awesomely amazing', I've never heard of lift much past 13mm even on the most radical of the newer stuff, street or race. "

____ I certainly 'hear' what you're saying, and I'm also still in awe & disbelief (of sorts) !
__ I very-much hope to post pix & confirm the figures, as soon as it warms-up enough for me to try & un-bury decades of accumulations in our (unheated) basement.


Hopeful-Cheers,
DCT-Bob