Valve Sizes

[frankfast]

He placed a Scrambler 250 piston in the Scrambler 250 head and it fit perfectly. Wish you were there. There must be an explanation.

[DewCatTea-Bob]

____ OKay, let me rehash all this out again to make sure I have all the details straight...
__ Your local DUKE-man took what was supposed to be a new DUCATI w-c 350-piston and found that while it would fit your stock DUCATI 350-head perfectly, it would NOT also identically fit with the stock DUCATI 250-head (which he has), without it's crown's dome making contact somewhere within it's combustion-chamber's inside-surface (well before the two squish-bands could make any contact) !?
__ And yet he also had a stock DUCATI 250Scrambler-piston which perfectly fit into the combustion-chamber of his stock DUCATI 250-head !? - (Sort-of makes me wonder how his 250-piston would've fit with YOUR 350-head!)
____ At this point, I'm thinking the following.....
Your 350-head is (possibly) one of a number which I know of that have been modified (here in the U.S. & Great Britten) to accept pistons which were originally made for Brit-bikes (such as a Triumph 750-twin), AND, the unused (76mm?) piston which your DUKE-man had tried in both your (modified?) 350-head & his 250-head was actually one of those Brit-pistons. (?!)
Nothing much else would make any likely sense (on this issue) to me !
And I really wish that Eldert would let us know if he's got anything to say about this mystery-issue, or not. _ (He may be staying-off it, knowing that it's a waste of his time to bother with.)


Hopeful-Cheers,
-Bob

[frankfast]

Since I've decided to retain my 350 head with large valves and will install a white cam from a 250, are there any valve timing issues to be taken into consideration or do I just line up the dots?

[DewCatTea-Bob]

" are there any valve timing issues to be taken into consideration or do I just line up the dots? "

____ I've installed the 'White-cam' -(from both 250 & 450 SCR-models) into large-valve 350-heads on three 350-DUKEs (with favorable results!), and each time simply installed the camshaft leaving all the original gear timing-marks/dots aligned as stock.
__ I doubt that the intended (actual?) valve-timing of the White-cam could be made more useful either retarded or advanced, from stock.
____ If anyone would like additional info about valve-timing and has obtained accurate valve-timing figures with their installed camshaft, let me know what your figures are and then I'll let ya know if there might possibly be any usable advantage gained by any alteration of the overall bevel-timing.

____ I believe that Graham may prefer swapping cams with you, since you both may have the cam which the other prefers.
So you may want to check-into that before going fourth with installation.


DUKE-Cheers,
-Bob

[frankfast]

I would rather have the green/white cam so if you're listening Graham and are interested in the swap, please let me know. Thanks Bob.

[DewCatTea-Bob]

" I guess I better get a move on and remove my cam so I can measure it up then!! "

____ It seems as if I'm the only one who's ever concerned that there seems to be TWO different camshafts that are both considered to be The 'Green&White'. ...
There's the original one, and then there's the later one which I was told by John White (formally of DomiRacer), was the very same cam designed for the 250F1 -(racer 250).
The later example of which, really ought to be avoided except for all-out top-RPM type racing (without muffler!) !
Since two otherwise identical 350s (each with the opposite G&W-cam), the 350 with the nonF1-cam will have the edge at all RPM-ranges (except near red-line AND in the event that both are without a muffler).
It's inexplicable to me as to why any enlightened rider would prefer the F1/G&W-cam for any use other than race-track racing ! _ Cuz on the road -(non race-track type), a 'street-legal' White-cam equipped 350, (under all riding conditions), will AT LEAST stay even with it's otherwise equivalent G&W-cam equipped 350.


" noticed that my exhaust nut threads on the head are stripped "

____ That's often caused by somebody who did not have the 'knack' to get such (used) threaded items naturally-aligned before-hand,, and also, such worn threads most often get that way from leaving the ex.nut loose too long.
__ If you have-the-knack to be properly-careful (and I'm sure that Graham ought to be the type), ya can (relatively cheaply) fix-up such messed-up exhaust-threads in the cyl.head, with the use of a 750/850 MotoGuzzi ex.flange-ring/nut. _ As THEIR -(Guzzi equivalent)- ex.nuts, (like a thread-tap), have sharper & deeper threads, (which will also still work with such stripped-up cyl.head threads where a stock ex.nut no longer will).


" 2 fins are broken on the barrel "

____ Do you mean on the cylinder-jug/barrel ? _ Or were you meaning to refer to the ear-tab/fins of the threaded exhaust-ring/nut?


DUKE-Cheers,
-Bob

[frankfast]

If I do end up having a green/white, I would be interested in a swap with you. How quickly do you need to know?

As soon as you are able.