Camshaft Data

[DewCatTea-Bob]

____ Seems like you've read my previous-post before I finished it !?


" using a set of rockers from a narrowcase Scrambler in my widecase Scrambler should not present a problem "

____ That's right! _ Although they may not APPEAR to be exactly the same,, they actually ARE, dimensionally.


" since neither incorprorate screw type adjusters. "

____ Well that fact is actually not a concern in this case (since you're starting-out with the less-versatile type of rockers, in the first place), especially since the screw-adjuster type rocker-arms are actually MORE versatile and thus can be used in situations where the std.type rockers will not allow sufficient free-space !


" Also there shouldn't be an issue using the cam from the narrowcase. "

____ Now THAT's a possible combo, where I've run-into the clearance-issue ! ...
I once tried to fit a n-c Monza-cam into a 350SCR-head -(which had had just one valve-seat job), and the base-circle of the Monza-cam was so large, that there was then insufficient room to fit the thinnest shim-caps (without creating negative-clearance) ! _ So I then had to replace my project-head's original-rockers with a Monza's adjustable-type rocker-arms, to go-along with my chosen cam.
__ Since you're intending the use of a n-c SCR-cam,, then since it has a smaller base-circle (than the Monza's), you should be okay so long as your head's valve-seats are not ground-down too far. _ But you should probably look-forward to the likely need of the harder-to-find thinner valve shim-caps -(which range between 2 & 5mm).


Hopeful-Cheers,
-Bob

[frankfast]

Correct me if I'm wrong but I think the Monza and GT came with screw type adjusters but the Mach 1 and Mark3 came with shim adjusters. Did the narrow case Scrambler employ both types? And would you consider replacing the rockers on my 350 Scrambler which use the shim type (and which are well worn due to a broken oil pump) with screw type adjusters. I believe the screw type are preferred due to ease of maintenance but the shim type are used for higher performance machines.

[DewCatTea-Bob]

" Correct me if I'm wrong but I think the Monza and GT came with screw type adjusters but the Mach 1 and Mark3 came with shim adjusters."

____ That's all quite correct ! _ The Sebring (which used the Monza-cam) also was stock with the screw-adjuster rockers.


" Did the narrow case Scrambler employ both types? "

____ No ! _ (Have I worded something which allowed you to think that?)
All SCR-type models were stock with only the std.shim-type rockers. _ However, I have installed a n-c SCR-cam into an otherwise stock Sebring-head, and that worked just fine !


" And would you consider replacing the rockers on my 350 Scrambler which use the shim type (and which are well worn due to a broken oil pump) with screw type adjusters. "

____ Yes, I certainly would indeed consider the non-stock screw-adjustable type of rocker-arms for installation into a 350SCR-head, BUT, not along with it's stock G&W-cam. _ As the screw-adjuster type rockers are likely too heavy at their valve-spring end to help avoid valve-float (near the rev-range where the G&W-cams are intended to come into play).
I would not consider using the screw-adjuster type rockers with any cam that's hotter/wilder than the Grey/M1-cam, in a 350 ! _ (And I'd certainly advise against using that type of rocker-arm even with the M1-cam, in any 250, [since 250s can rev higher] !)
I've never actually heard of anyone trying to install the screw-adjuster type rockers into any 250 along with the M1-cam, but I have known of a Sebring-owner installing the M1-cam into his otherwise stock Sebring-head (and along with a 27mm SSI-carb), and getting very favorable results with that up-grade-project.


" I believe the screw type are preferred due to ease of maintenance but the shim type are used for higher performance machines. "

____ That belief seems to be in-line with that which Ducati practiced.
I'm sure most others have stayed within those same original-lines too,
but certainly by now, I'm also sure that still others have gone outside those established lines, both purposely & ignorantly, (and probably without consequence as well, since I've never heard of any resulting issues).
And although the valve-springs are weaker in the Monza/GT/Sebring, on the exhaust-side,, the adjustable-rockers are still up to the task, since the intake-springs are the same for all (springer) models AND the intake & exhaust springs are the same for the large-valve models !!


DUKE-Cheers,
-Bob

[DewCatTea-Bob]

____ I'm wondering if Frank or anyone other of us, won the n-c SCR-cam & rocker-set that ended on eBay last night!?
Link follows here.....

http://cgi.ebay.com/ebaymotors/ws/eBayI ... K:MEDWX:IT

If ya take a close-look at the camshaft, you can then see that the base-circles of the cam-lobes are notably greater in diameter than that of the main body of the shaft itself ! _ That's typical of narrow-case camshafts.
Wide-case cams have their base-circle (relatively) about flush with the rest of the main shaft-body.
I believe a reason for why Ducati decreased the base-circles of their later cams, was to help keep workable clearances after more than one valve-job has been done on stock-heads.
__ If there happens to be anyone else here who wants such a n-c set, with adjustable-rockers, I'd let-go of a set for about that same amount and would even take-in a worn-set on trade towards it.
Otherwise, I may soon list an entire Monza/Sebring cyl.head on eBay (without removing those internal-parts).


DUKE-Cheers,
-Bob

[frankfast]

I came in second on both auctions and it seems that the same person won both sets. He was probably prepared to spend much more than I was. I questioned the first set that included screw type adjusters because it was advertised as a Scrambler. According to Bob, Scramblers only came with shim type adjusters. He did mention that the cam had a white paint mark on it. Bevel Heaven had commented that the second set (with shim type) was from an earlier narrow case Scrambler. I'm not sure how he could tell. Anyway, I'm interested in your offer Bob. Will you PM me. Thanks.

[DewCatTea-Bob]

" I questioned the first set that included screw type adjusters because it was advertised as a Scrambler. "

____ I missed a chance to see that seller's earlier listing for that cam & rockers set, (must have ended before I got to take a look at his other listings!)...
Could you please post the eBay-# of that listing, or a link to it? _ As I'd like to see the pic showing THAT cam & rocker set, as well.


" According to Bob, Scramblers only came with shim type adjusters. "

____ Either they were actually not from a real SCR-head, or (due to the thinner shims being very hard to find), were some time in the past installed into that supposed Scrambler, in place of the original std.type rockers ! _ As many DUKE-owners have preferred not having to bother with trying to find whatever valve-shims they need.


" He did mention that the cam had a white paint mark on it. "

____ That would seem to indicate that the cam was from a wide-case 250 or 450 Scrambler-model. _ And the rockers were NOT stock with that cam !


" Bevel Heaven had commented that the second set (with shim type) was from an earlier narrow case Scrambler. I'm not sure how he could tell. "

____ I'm also sure that's correct, as well...
While the cam appears to be either a n-c Scrambler or Monza type, (can't tell those two apart without being miked), that it was with a pair of non-adjustable std.type-rockers, would leave that deduction as the only choice !
(And I've already previously explained why that cam does not appear to be from a wide-case model.)


" I'm interested in your offer Bob. Will you PM me. "

____ Yes Frank, I'll get to that soon, later tonight.
However, I'd sorta prefer to see your w-c 350 (with large-valves) get a hotter-cam than a (violet) Monza-cam.
Not that the Monza-cam is notably weaker in power than any of the (4 different) 250SCR-cams, it's just a mind-set that seems righter !
Maybe you could later make a swap with Graham, who wishes to swap his (expected) G&W-cam for a milder one.


DUKE-Cheers,
-Bob

[frankfast]

The first rocker - cam set that was auctioned was Item #370398240204.

[DewCatTea-Bob]

" Will you PM me. "

____ I've finally sent you a PM, Frank. _ Although I was not able to confirm that it's actually been sent-out .
Please post here noting if you didn't get my short non-direct email.


____ Thanks for posting the listing-number of that other cam & rocker set sold by that same eBay-seller, Frank !
I've since looked-over the picture showing the cam of that set... It seems that the seller has parted those three items from a narrowcase-Scrambler which at one time must have had it's original (Brown) cam and std.rockers replaced with a brand-new White-cam & and screw-adjuster type rockers. _ (The winner of that slightly-used set, got a very good deal !) _ Here's a link to that eBay-listing.....

http://cgi.ebay.com/ebaymotors/ws/eBayI ... &viewitem=

Note the added-info about the camshaft still having it's white-paint with print, (which is usually only found just on UNused camshafts).
__ If ya look closely at the camshaft in that pic, ya can clearly see that the cam's base-circle of the intake-lobe (nearest the threaded end) is almost flush with the shaft itself... That's typical of most all widecase-cams, and (along with what can be seen of the shape of the two lobes), tends to confirm that the camshaft is indeed a 'White-cam'.
Unfortunately in that pic, the camshaft is not positioned so that the exhaust-lobe's base-circle can be (at least equally) clearly seen, as well. _ In fact (from what I perceive), shadows caused by the direction of the main lighting for the pic, seem to make the base-circle of the ex.lobe APPEAR to be much larger than that of the in.lobe's, (to an extent that it's size seems to be at least that of a narrowcase-cam's base-circles).
I've never seen either a n-c or a w-c camshaft which had it's two base-circles much more than a few thousandths different in size ! _ So I have to conclude (despite the appearance) that the ex.cam's base-circle (of that camshaft) must also be about flush (with the shaft), like the in.cam's base-circle is.
__ If there's anyone else who pays attention to detail as I do, I'd like your opinion of what YOU perceive of this issue from that picture.
It's too bad that I didn't find that listing before it ended, as I would've then asked for some mike-readings of that cam.
Hopefully, the winner will eventually find this post and offer the actual info about it !


Hopeful-Cheers,
-Bob

[DucBevellvr]

I'm thinking of putting a larger carb on my 250 Monza, and since I have an old 250 Scrambler which should have it's head rebuilt anyway,
I wonder if it would be very advantageous to swap the Scrambler head's cam / rockers, with the Monza's? (The Scr may become just a parts bike anyhow.)

Bevel Dreams,
JeffP

[DewCatTea-Bob]

" and since I have an old 250 Scrambler which should have it's head rebuilt anyway,
I wonder if it would be very advantageous to swap the Scrambler head's cam / rockers, with the Monza's? "

____ I'm afraid not so enough to really make it all worth your trouble, as the n-c Scrambler-cam is basically the same cam as the Monza's with just a slightly smaller base-circle thus providing only a slightly greater lift and a bit wilder valve-timing that's not really going to produce enough additional power to easily notice.
So I'd suggest using which-ever rocker-type you prefer for your Monza, and after you've got done whatever work your Scrambler-head needs, you then swap-over the entire Scr.head & cam onto your Monza. _ And then that way, your 2mm-larger intake-port will then better match-up with your larger-carb which you wish to use.


Dukaddy-DUKEs,
-Bob