Points Adjustment.

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Bevel bob
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Re: Points Adjustment.

Postby Bevel bob » Mon Jun 07, 2010 6:14 pm

Hi Bob, The cam will be coming out again as I'm not happy with the shimming (seems to have gone a bit tight since I put the head on). A mate is also looking for a thicker thrust washer(29.2x35x0.5) to go in the bottom bev housing.(which will change the shimming again) To set up as you suggest I will need some smaller lash caps specialy ground to give 1mm.

DewCatTea-Bob
Posts: 2897
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Location: Near SE side of Lake Michigan

Re: Points Adjustment.

Postby DewCatTea-Bob » Mon Jun 07, 2010 8:46 pm

" The cam will be coming out again "

____ Do you have 0-1 & 1-2 inch micrometers -("mike"), or a 0-2 inch caliper to measure your cam's base-circle & lobes with?


" I'm not happy with the shimming (seems to have gone a bit tight since I put the head on). "

____ The valve-clearances can't possibly change only due to cyl.head installed or removed (unless perhaps the camshaft/bevel-bearing is bad) !
In either case, that clearance should be checked/set only while the pair of timing-dots on the tower-shaft & camshaft bevel-gears are exactly aligned, (which would also be when the engine is at power-TDC) !


" I will need some smaller lash caps specialy ground to give 1mm. "

____ Please understand that the "1mm" preset clearance-gap is just one possible setting for taking v.timing readings at ! ...
__ For one instance, lets say that you just happen to have a valve-stem shim/lash-cap which happens to provide 15-thousandths of-an-inch of clearance for your ex.valve & rocker,, then, you would need to find another shim/lash-cap -(v.cap) which will give ya exactly a .015" gap also for the intake side as well !
__ Or for another possible instance, ya may have a v.cap which leaves a clearance-gap of .50mm between the intake valve & rocker,, then in that particular case, you would need to find another v.cap which also provides that exact-same .5mm gap for the exhaust side too.
Etc., etc.
__ However, any such shared preset clearance-gap (for taking/recording valve-timing readings for both valves), should be between .015" & .040" of an inch, since any amount less than at least double the normal running-clearance would likely cause running-into the 'clearance-ramps', which would thus cause crazy/far-out & way-off valve-timing readings !
__ Only by taking this kind of work short-cut, will you be able to obtain reading-figures which can then be correlated with the factory-specs.


DUCATIly,
-Bob
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

Bevel bob
Posts: 1043
Joined: Thu Apr 15, 2010 8:01 am
Location: Bromley Kent UK.

Re: Points Adjustment.

Postby Bevel bob » Tue Jun 08, 2010 2:50 am

Hi Bob, yes I have mikes,calipers and dial gauges,the cam drive tightened up when i fitted the head,(or seemed to!) its possible that my unorthodox method of shimming the bottom bevel has left no clearance at the stepped shaft joint, I will plastigauge it to see. Am waiting to see if alternative thrust washers are availiable (not up till now!) ,if so I will do it all again the normal way.

DewCatTea-Bob
Posts: 2897
Joined: Sun Nov 01, 2009 10:53 am
Location: Near SE side of Lake Michigan

Re: Points Adjustment.

Postby DewCatTea-Bob » Wed Jun 09, 2010 11:08 am

" yes I have mikes,calipers and dial gauge, "

____ Okay, good! _ Then you can figure-out which cam you actually have and know about what valve-timing you should expect from it.
__ Each cam-lobe has has it's 'opening-ramp'; 'peak'; & 'closing-ramp' poking-out above the 'base-circle' of the cam (on the camshaft),, and of course each lobe has it's own base-circle...
So you have to measure the base-circle and also the whole 'cam' -(a "cam" is both the lobe & it's base-circle!), then subtract the base-circle measurement from the entire cam measurement in order to get the 'lift' figure of the cam.
__ Providing ya know how to play with a caliper or a mike,, then you need to find the smallest possible measurement of the base-circle, and also the largest possible measurement of the whole "cam" (from the tippy-top of the lobe-peak, to the base-circle 180-degrees opposite).
__ I have a collection of just about every std.production DUKE-camshaft, from most every DUKE-model that Ducati ever produced. _ And I've never found any two different MODELs of cams which share the exact-same lift-figures. _ So by getting the lift-figures of your cam, we can then determine which model of camshaft you have.
__ Now I know that the cams found in wide-case 350s were paint-coded Green&White, as I've actually seen such examples for myself. _ But I've never seen a camshaft which was actually from a 250F1, which is also supposed to be a Green&White cam ! _ However, I've found Ducati factory-specs which indicate the exact-same valve-timing for both the w-c 350 & the 250F1 ! _ Which of course stands-to-reason (since they both have the same color-coded camshaft).
But what doesn't stand-to-reason, is that Ducati has published two different sets of valve-timing figures for their w-c 350s, plus I've also found examples of each within stock w-c 350s !
__ I've been intending to place a post giving all the figures of every camshaft-model I have but, it's still going to be a while before I get to accomplishing that task.
I once knew all those figures by heart but now don't recall them all well enough to trust POSTING them...
As I'm recalling at the moment, the real w-c 350-cam's exhaust-lobe has a 'lift' of 8.5 or 8.6mm, while the 250F1's is 8.8 or 9.0,, and the w-c 350 intake-lobe's lift is 9.8 or 10.0mm, while the F1's is 10.0 or 10.2mm. ...
The problem is that these two different G&W cams LOOK the same by eye, and ya can only tell them apart by measuring there slightly different exhaust-lobe lift.
__ I've been lead to believe that at some point, the Italian-gov forced Ducati to cut production-costs on camshaft-production, and so Ducati started installing the (slightly wilder) racing-cam from the 250F1 into the std.production 350s, (since they needed to keep making the F1-cam for the very few F1-models, in any case).
This subject is actually somewhat of a mystery to me, so I'd like to know what other established 'DUKE-heads' think they know about this G&W/F1 cam story ! _ And for any of those of you who were unaware of these two different cams, and have a 250F1-cam and/or a wide-case 350-cam,, please do the measuring & figuring of your cam's lift-figures, and let us know what you've come-up with.
__ So Bevel-bob, which factory-spec valve-timing figures were you expecting, for YOUR G&W-cam?


DUCATIly,
DCT-Bob
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

DucBevellvr
Posts: 10
Joined: Sat Apr 10, 2010 3:02 pm

Re: Points Adjustment.

Postby DucBevellvr » Fri Jun 11, 2010 11:21 pm

Hey-there DCT-Bob,

You've brought up an interesting subject about what cams were stock in which Duke models and how the various models of cams must differ!

Now I got into Ducatis for several reasons but, one reason was from talk I overheard in the past by others about the cams used by Ducati. And that led to me picking up some questionable information about them,
like how some of the 350s (which don't have a Desmo cam) will have some sort of a "racing cam" in them stock from the factory called a "green with white cam" , and other 350s have a much undesired cam that is to be avoided when looking for hot Ducati cams.
So I already knew that there were at least 3 models of cams in the various 350s but I have never learned for sure how to tell which 350 model came with whatever cam.

I would like to know because I might become more interested in buying back a 350 I once owned before, as a new Duke project to take on.
It's a widecase but other than that I was never very sure what model it actually was because, it had a lot of BSA parts put on it when i first got it.
Can you give me any idea at all of which 350 model-years have whatever cam, and which cam is best for whatever it's best for?
And if you have the spec figures for any or all, how they differ from one another and if those differences are good or bad for whatever, etc.

Sorry to bother you with this stuff Bob but, I always had an interest in this stuff and never got all my old questions answered by any manuals or other sources who were in agreement,
and your last post here has got my old interests fired back up!
I guess I really don't need to know but, it's kind of exciting in a way, if you know what I mean. So I hope you can at least feed my building apitite (for this kind of info)
a tidbit or two on the subject!

thanks,
jeffP.

DewCatTea-Bob
Posts: 2897
Joined: Sun Nov 01, 2009 10:53 am
Location: Near SE side of Lake Michigan

Re: Points Adjustment.

Postby DewCatTea-Bob » Sat Jun 12, 2010 9:08 am

" You've brought up an interesting subject about what cams were stock in which Duke models and how the various models of cams must differ! "

____ I most certainly do agree with you on that Jeff ! _ I've always been quite intrigued with the various cams used in DUCATIs, and so I've learned as much as I could about their specs & their effect on engine-power !


" like how some of the 350s (which don't have a Desmo cam) will have some sort of a "racing cam" in them stock from the factory called a "green with white cam" , "

____ That's actually true for most wide-case (only) 350-models ! _ I believe both the 350Mark-3, and later 350SCRs -(named: 'SSS' by Berliner) all seem to have come stock with the '250F1' racer cam.


" and other 350s have a much undesired cam that is to be avoided when looking for hot Ducati cams. "

____ That would be the 350-Sebring models which were stock with the milder cam from the 250-Monza !
The first 350s (of 1965) were narrow-case Sebring-models, which the factory was afraid to let make too much power because Dr.T had been much opposed to his 175 motor-design being subjected to the power of twice the displacement. _ So they decided to keep their first 350 model mildly-tuned and so thus chose the Monza's cam & small (24mm) carb along with an even lower compression-ratio -(8:1, instead of the Monza's 8.5:1) !
(Actually, I'm fairly sure that those decisions had already been previously made for the 300cc-motor [of the GT-model, which got skipped-over], and were simply past-on to the 350 -[actually 340cc], after Berliner twisted Ducati's arm to stroke-out the previously-planned 300 -[76x66], to become a 350 -[76x75mm] asap, back in 1964.)


" Can you give me any idea at all of which 350 model-years have whatever cam, and which cam is best for whatever it's best for?
And if you have the spec figures for any or all, how they differ from one another and if those differences are good or bad for whatever, etc. "

____ I'll provide some more details on this but I'd prefer to place it within another thread, since this subject is well off from the topic of "Points Adjustment" ! _ If I don't find another existing/appropriate thread for such, I'll then start a new thread. _ You should find my intended extended-report started (but not finished) before too very long, (as I'm more apt to get to doing it, if I don't expect myself to get it done all at once!).


" it's kind of exciting in a way, if you know what I mean. "

____ Yes I do, as I've been quite familiar in the past with the feeling of learning about DUCATI-cams also ! _ In fact, I'd still be pretty excited to learn the lift-specs of any DUKE-cam which I never had the chance to examine before ! - (Such as the real 450-Mark3 cam & the real 250GT cam.)


DUKE-Cheers,
DCT-Bob
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


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