Camshaft Identification

[Ian B]

Sorry to bring up yet another camshaft topic but the more I read on the forum the more confused about which cam I should use on which engine. I have two complete nc engines in bits. A 250 and 350 and a fully built up 250. Between these I have 6 cams and could use a little help identifying them as the paint marks on all except one are long gone! Getting out the vernier didn't help either as they're all different so no clues there either! The only one I'm sure of is stamped 2.5 SCR. Is this the same as a standard 250 white cam?

1&2.jpg

The left one is the 2.5 SCR. Both look similar but have quite different circle diameters and lobe heights.

2&3.jpg

This is cam 2 again and cam 3 which seems to have more duration (if that's the right term)

3&4.jpg

This is cam 3 again and cam 4 which has a lot different profile.. any ideas or comments greatly appreciated.

I have the circle and lobe height measurements if it's needed to help identification. Hopefully one of them is the Holy Grail of Ducati cams which will help pay for other bits I need!

Once I know what they are I only have to decide which to use and whether to use solid or adjustable rockers... I guess that's another thread!!!

Many thanks for putting up with us newbies..

[DewCatTea-Bob]

Sorry to bring up yet another camshaft topic but the more I read on the forum the more confused about which cam I should use on which engine. I have two complete nc engines in bits. A 250 and 350 and a fully built up 250. Between these I have 6 cams and could use a little help identifying them as the paint marks on all except one are long gone! Getting out the vernier didn't help either as they're all different so no clues there either! The only one I'm sure of is stamped 2.5 SCR. Is this the same as a standard 250 white cam?

1&2.jpg

The left one is the 2.5 SCR. Both look similar but have quite different circle diameters and lobe heights.

2&3.jpg

This is cam 2 again and cam 3 which seems to have more duration (if that's the right term)

3&4.jpg

This is cam 3 again and cam 4 which has a lot different profile.. any ideas or comments greatly appreciated.

I have the circle and lobe height measurements if it's needed to help identification. Hopefully one of them is the Holy Grail of Ducati cams which will help pay for other bits I need!

Once I know what they are I only have to decide which to use and whether to use solid or adjustable rockers... I guess that's another thread!!!

Many thanks for putting up with us newbies..

____ This topic-matter concerns my second-favorite Duke-subject ! _ So I'll be glad to get all this straightened-out for you (to a detail-level likely not found anywhere-else in the current world) !

Stay-Tuned,
-Bob

[DewCatTea-Bob]

[quote= Ian B ...
" Sorry to bring up yet another camshaft topic "

____ No need to be sorry,, as I for one, appreciate it !



" the more I read on the forum the more confused about which cam I should use on which engine. "

____ I wish you had questioned whatever you've read from whatever thread-posts that left you so uncertain. _ As then I probably could've better made sense of it-all for you.



" I have 6 cams and could use a little help identifying them as the paint marks on all except one are long gone! "

____ That's typical for used-camshafts,, but missing white-paint wouldn't reveal very-much anyway, as there's at-least four different Scr.type cam.models which were labeled with that SAME color-code !
__ Can you also post equally well-executed view-shots of your other two camshafts as-well ?



" Getting out the vernier didn't help either as they're all different so no clues there either! "

____ ACTUALLY, the varied reading differences that can be measured, are your most certain clues as to which cam-model is which !



" The only one I'm sure of is stamped 2.5 SCR. Is this the same as a standard 250 white cam? "

____ There's really no 'standard' white-cam, since the white color-code was overused on so many different Scr.type cam.models ! - (Unless it was ever to-be established that the original Motocross-cam ought be entitled as the 'standard-white'.)
__ I believe the shaft with the '2.5 SCR' stamping is a wide-case Scrambler-cam.



" The left one is the 2.5 SCR. "

____ That left-one (within your top-pic), with it's rather-thin lobe-shape & small base-circle is most-definitely original to a w-c.Scrambler-model !



" Both look similar but have quite different circle diameters and lobe heights. "

____ The other cam (seen on it's right-side, [as your #2]),, looks to be a n-c.type cam.model from either a pre-1968 Motocross/Scr, or possibly a Monza/Sebring.



" This is cam 2 again and cam 3 which seems to have more duration (if that's the right term) "

____ One is probably a 'Violet-cam', while the other is a n-c.Scr-cam.
Due-to fairly similar left-to-duration ratios, it's not easy to see the difference between a Monza/Sebring-cam and a n-c.Scr-cam (which don't have greatly differing durations),, but assuming near identical base-circle measurements, the cam with the narrower/smaller-looking lobes is most-probably a Violet-cam.



" This is cam 3 again and cam 4 which has a lot different profile.. "

____ The left cam (in the bottom-pic) with it's large base-circle strikes me as being the rather-mild Violet-cam as compared to the (ultra conversely) WILD cam seen pictured next to it (boasting a wild-type profile).



" any ideas or comments greatly appreciated. "

____ At first-glance, your #4-cam appeared to be the much-desired Mach-I/Gray-cam,, but once I took a closer look (and saw it's near complete lack of any protruding base-circle, it then became quite obvious that your #4-cam (as seen on the right-side of your bottom-pic), is a Green&White cam-model. ...
__ Do you intend to install it in a racing-engine that's expected to make good-use of a racing-Duke's top-speed ?



" I have the circle and lobe height measurements if it's needed to help identification. "

____ If you'd prefer rather definite cam.model identification,, then we need min.base-circle measurements to subtract from overall max.cam-diameter/height, in order to figure the cam-lobe's lobe-lift. _ And with that info revealed, I can then tell you (for sure) what cam.models your camshafts actually are.



" Hopefully one of them is the Holy Grail of Ducati cams which will help pay for other bits I need! "

____ The 350Mk3/G&W.cam is the closest to such description,, but your G&W.cam might be the 250F1-version, which is too-wild (in 250/350s) for anything other than off-street racing.
Either Green&White-cam version ought-to get you well-over a 100-bucks.



" Once I know what they are I only have to decide which to use and whether to use solid or adjustable rockers... "

____ It would be of interest to discuss your intentions for the motors that you choose to install any particular camshaft into, and what ex.pipe/muffler & carb & cyl.head models you intend to use in combo together with them.


Fun-Cheers,
-Bob

[Ian B]

[quote= Ian B ...
" Sorry to bring up yet another camshaft topic "

____ No need to be sorry,, as I for one, appreciate it !

____ It would be of interest to discuss your intentions for the motors that you choose to install any particular camshaft into, and what ex.pipe/muffler & carb & cyl.head models you intend to use in combo together with them.


Fun-Cheers,
-Bob

Wow.. many thanks for the comprehensive response Bob. Camshaft 5 looks virtually identical to one of the others and has similar measurements and cam 6 is in my only fully built up, ready to go (hopefully) engine!

These bikes were stripped 17 years ago and a restoration started with frames powder coated and bits polished and re-chromed where required. As far as I have found out, the one which is built up is a 1964 Diana which sadly has no original tinware but I do have a very pretty long thin cafe racer tank which I intend to use and make it a pretty little road bike. Engine no. DM250 81987.
I also have a nc Sebring which was first registered here in 1971 but I think is older, engine no. DM350 04106. I have most of the standard parts so will build this up to be fairly standard with an Amal 926 or 930 carb as these are what I have!
The third bike was a racebike in the 70-80's with what i think (from reading this forum!) started life as a scrambler engine as it has the chain guard bolt hole. The engine no. is 102856 and frame no. 78582 and I know nothing else of it's history. Sadly the race crank is u/s but I do have a standard 250 crank in good condition which I intend to use. Also the head is cracked through to the inlet port radiating out from the valve guide and has been epoxy'd up around the valve spring seat area years ago by the look of it. I don't know whether to leave it as-is, get it welded and machined up or try and find a replacement standard 250 head. The outer case has the kickstart hole welded up and the bush inside the engine removed so it will be bump-start only. I intend to build this to look like a classic racer but only use it to parade or show.
In the stock of parts I have two new Ducati Silentium silencers so will use these on the two road bikes and an open mega on the (pretend) race bike. On second thoughts I may sell one Silencer and use something more suitable for the Diana cafe racer...... Still at the changing my mind period!!!

My main priority is that all are easy to start and run well. They'll all be used gently rather than thrashed to the limit...

Thanks once again for you're input and I and many others I'm sure really appreciate all your help here.

Cheers
Ian

[DewCatTea-Bob]

[quote= Ian B ...
" As far as I have found out, the one which is built up is a 1964 Diana
Engine no. DM250 81987. "

____ You should now realize that a 1964-model would have a 5-speed motor, yet the motor-number which you state for it must be a 4-speeder (as all [non-Mark-III] Diana-models have been) ! _ So your 'Diana 250' is likely no newer than a 1962-model.




" I also have a nc Sebring which was first registered here in 1971 but I think is older, "

____ You're certainly right about that, as that n-c.model was retired before 1968.



" engine no. DM350 04106. "

____ I believe that motor-# might be a 1965-model.
__ Does it's kick-starter always engage properly ?



" I have most of the standard parts "

____ Then if it's a '65-model, it ought-to have the old rounded-style body-parts (rather than the 1966 squarish-style replacements).



" with an Amal 926 or 930 carb "

____ The 26mm-Amal is a better match for the stock Sebring-cyl.head !




" i think
started life as a scrambler engine as it has the chain guard bolt hole. The engine no. is 102856 "

____ That's a new enough 1966 n-c.Scr-model to be getting pretty-close to the last of them before the WideCase-versions replaced them in 1967.



" Also the head is cracked through to the inlet port radiating out from the valve guide and has been epoxy'd up around the valve spring seat area
I don't know whether to leave it as-is, "

____ That may be okay as it is, merely for your intended show-bike.



" get it welded and machined up or try and find a replacement standard 250 head. "

____ I'm sure you could acquire a replacement head more economically.



Duke-Cheers,
-Bob

[Ian B]

____ I believe that motor-# might be a 1965-model.
__ Does it's kick-starter always engage properly ?

I don't know Bob, it's all in hundreds of bits and I've never seen it together! Is there a known weakness with anything other than the leaf springs (which mine doesn't have) that I've read about? Mine has the circular spring with 2 bolts holding the retaining plate.

____ I'm sure you could acquire a replacement head more economically.

Not sure about that here in the UK unless anyone knows of one available?

[double diamond]

Ian, if you have some measurements from your cams (base circle and maximum lift from intake and exhaust lobes), I have some measurements from various cams that might identify yours more positively. Also, regarding the engine number of your 4-speed Diana, is the “DM250” stamped on the right side center case or on the left side?

[Ian B]

is the “DM250” stamped on the right side center case or on the left side?

It's stamped on the right hand case and number on left..

The measurements:
Cam1 Marked with 2.5 Scr

Inlet Exhaust
22.15 22.0
30.18 27.93

Cam2

Inlet Exhaust
24.80 24.8
33.00 32.38

Cam3

Inlet Exhaust
25.20 25.30
32.98 32.95

Cam4

Inlet Exhaust
20.66 20.57
30.54 28.97

Cam5 (Marked with traces of white paint)

Inlet Exhaust
23.50 23.90
31.66 31.81

I look forward to see if any of these match up to yours...

Cheers

[DewCatTea-Bob]

[quote= Ian B ...
" Mine has the circular spring with 2 bolts holding the retaining plate. "

____ Then your n-c.350-motor should be a 1966-model !



" Not sure about that here in the UK "

____ Here in the USA, such used-cyl.heads have usually sold for under $150.
I have such spares, (but not much interested in shipping outside the U.S.).




" The measurements: "

____ I find suspicious figures (which I've colored red) with some of the measurements as they're stated...

Cam1 Marked with 2.5 Scr

Inlet _________________________________ Exhaust
22.15 ________________________________ 22.0
30.18 ________________________________ 27.93

____ The intake lobe-height of 8mm is as expected for a w-c.250-Scrambler,,
however it seems that the exhaust-lobe is badly worn about 2mm, as it should be rather near 7.8mm !

Cam2

Inlet _________________________________ Exhaust
24.80 ________________________________ 24.8
33.00 ________________________________ 32.38

____ Other than an odd-ball cam that Eldert has measured, I don't know of any cam-model which also has a 8.2mm in.lobe-height !
However the 7.6mm height of the ex.lobe is rather consistent with a pre-1967 n-c.Scrambler-cam.

Cam3

Inlet ________________________________ Exhaust
25.20 ________________________________ 25.30
32.98 ________________________________ 32.95

____ The 7.8mm height of the in.lobe and the 7.65mm height of the ex.lobe, are both consistent with the pre-1967 n-c.Scrambler cam-model.


[

b]Cam4[/b]

Inlet ________________________________ Exhaust
20.66 ________________________________ 20.57
30.54 ________________________________ 28.97

____ The 9.88mm in.lobe-height and the 8.4mm ex.lobe-height is consistent with the Green&White 250F1 racing-cam (which is commonly found within 1969-70 350-Scr.models).
__ I hope your stated measurements were particularly precise in this case, as both lobe-height figures have their tolerance-range tipped towards the '350Mk3' G&W.cam-model's figures (of 10mm & 8.5mm).

Cam5 (Marked with traces of white paint)

Inlet ________________________________ Exhaust
23.50 _______________________________ 23.90
31.66 _______________________________ 31.81

____ The 8.16mm in.lobe-height and 7.91mm ex.lobe-height are both fairly consistent with the w-c.Scr-cam that Eldert has measured, (which I highly-suspect came from a non-USA 450-Scrambler).


Duke-Cheers,
-Bob

[Ian B]

____ I find suspicious figures (which I've colored red) with some of the measurements as they're stated...

You are of course correct! Dyslexic moment!

Cam 1 should read 29.73 not 27.93...

Cam2

Inlet _________________________________ Exhaust
24.80 ________________________________ 24.8
33.00 ________________________________ 32.38

Just re-measured quickly and get 32.45 not 33.00
Thanks again!