450 Mark 3 Camshaft Change

[machten]

Hi All,

Seeing as I was rebuilding my 450 Mark 3 springer (and my wife is overseas for 5 weeks), I took the opportunity to do something about replacing the current 250 Scrambler White camshaft that is currently in the 450 and causes the poor thing to have an asthma attack after 5000 RPM . Road & Race have had Green & White spec cams made up and after keeping my eyes open without joy for a second hand one, I decided to just buy a new one. (The accountant tells me my company has had a good year!)

This has been talked about in several earlier threads, but I have an opportunity to post some comparative pictures, so thought I would do so...so here they are...

The White camshaft as from the factory..

IMG_1465 (1024x768).jpg

The Road and Race G&W replica...

IMG_1464 (1024x768).jpg

The specifications ... reckon this'll make a difference!!

Cam Compare.JPG

Regards,

Kev

[machten]

A longitudinal view displaying a slight lightening of the R&R camshaft. Consistent with what VeeTwo did with their aftermarket camshafts.

IMG_1466 (1024x768).jpg

The R&R cam with a requirement for more lobe metal weighs in at 242g against the white cam's 248g.

Kev

[DewCatTea-Bob]

[quote= machten ...
" I took the opportunity to do something about replacing the current 250 Scrambler White camshaft that is currently in the 450 "

____ It's nice that you already realize that your non-DESMO 450 may've come with a White/Scr.cam which was originally intended for a w-c.250-Scrambler.
__ The valve-timing of that particular 250-cam is...
IN. 27BT - 75AB _ EX. 60BB - 32AT , (with 8mm & 7.8mm lobe-lifts).
While the valve-timing for the REAL 450Scr.cam is...
IN. 30BT - 84AB _ EX. 63BB - 38AT , (with 8.5mm & 8.2mm lobe-lifts).
And the valve-timing for the 450Mk3.cam is...
IN. 60BT - 75AB _ EX. 75BB - 45AT , (lobe-lift figures are unknown to me, but are probably 10 & 9mm).



" Road & Race have had Green & White spec cams made up "

____ I suppose they copied the 250F1-version ?
Have you checked-out the actual lobe-lift of it's ex.cam-lobe ?



" I have an opportunity to post some comparative pictures,
so here they are...

____ Thanks for your posted-pix !



" The specifications ... reckon this'll make a difference!! "

____ Indeed SO ! ...
This change, (assuming the copied-cam is pretty-much the same as the G&W/250F1-cam), will transform your 450's performance into being the same as a 450-DESMO model ! - (Actually it will even be slightly superior but, you won't be able to tell that without a very sensitive dynamo-meter.)
__ I've made the same cam-swap between 350 & 450 Scrambler-models quite a number of times, and the exchange was always very beneficial for BOTH engines' performance !!
Although the 350Mk3/G&W.cam provided the most desirable performance (when running with a straight-through type muffler), and the M1/Gray-cam provided the funnest 450-performance.
I've been told that the 450Mk3-cam is the MOST desirable, but I-myself unfortunately never had an opportunity to try-out one of those cam.models.
__ If you run with a very restrictive muffler, then be prepared to experience rather inferior take-off power -(low-end torque) compared to the stock-cam.


Hopeful-CHEERs,
DCT-Bob

[machten]

I've been told that the 450Mk3-cam is the MOST desirable, but I-myself unfortunately never had an opportunity to try-out one of those.

No, me either Bob. I've heard of them but never seen one (IIRC the "Black" cam?)

I have ridden alongside a 71 350 Mark 3 with the G&W cam with my 450 in the Italian mountains, and whilst my 450 torque would keep me ahead down low, once we got to even a short straight, I'd hear that damn thing hit its sweet spot at just under 6000 and go right past me. I'm not expecting to rev my 450 way up high, but that white cam in a 450 makes no sense to me at all.

I guess I'm expecting the G&W to be a good "streetable" cam solution in a 450...I think it's a little high end in a 350 in that it leads to too much loss down low. I'll see soon enough.

Kev

[Eldert]

a camshaft maker is making me some cams with the Mach 1 grey cams timing and a little more lift ( 11 mm intake and 10 mm exhaust ) for my 500 RT playbike . let see how that works out .

Eldert

[DewCatTea-Bob]

[quote= machten ...
" I've heard of them but never seen one (IIRC the "Black" cam?) "

____ I believe the Black-cam is actually the 250GT-cam's color-code.
I think I was told that the 450Mk3-cam was color-coded 'Blue'.
Was also told that it's valve-timing was almost the same as the 350Mk3's (and certainly less than the 250F1's), but with higher lobe-lifts !
__ I've been left somewhat unsure as to whether-or-not the 450Mk3.cam is actually a different cam.model than the so-called 'Special' camshaft for the (non-DESMO) 450.
I've never had hands-on either described 450-camshaft, so I'm sort-of in the dark on this concern.
However I do know that the 'Special 450-cam' (which had to be 'special-ordered' !) was considered as a semi racing-cam, and never came stock in any std.production-model. _ Yet the 450Mk3.cam has (supposedly) been found in some 450Mark-3 models, (instead of the rather common w-c.250Scr.cam). _ And besides that,, the claimed valve-timing figures of the 450Mk3.cam, don't really approach racing-cam specs (such-as like those of a 900SS).
So even-though I've sometimes confused the two described 450-cams, I've always considered them to actually be two rather different cam-grind/models.
Anyhow, every time I ordered one of those 'Special-450' or 450Mk3 cam.models (back in the '70s), both descriptions were unfortunately always 'back-ordered' on me !
I still recall the part-number as being 0615.29.010, (or maybe 0616.29.010 [which I rather believe to be the 'Special 450DESMO-cam'] ).
__ What we really need are more older-members (like myself), who were the ones (back-in-the-day) who actually got & tried-out such rare cams, to tell us all they know about them !


Duke-Cheers,
DCT-Bob

[DewCatTea-Bob]

[quote= Eldert ...
" a camshaft maker is making me some cams with the Mach 1 grey cams timing and a little more lift ( 11 mm intake and 10 mm exhaust ) for my 500 RT playbike .

____ That's very interesting Eldert !
(The valve-timing of the M1/Gray-cam is: IN. 62BT - 76AB _ EX. 70BB - 48AT , [with lobe-lifts of 9 & 8.5mm] ).
I'm very sure that such a cam would work great for a stock 435cc engine, but I think it's too mild for a "500" (with the same standard sized ports & exhaust-system) !
__ (For most-all large-valve 250/350/450 engines, I'd rather suggest including the wilder figures of the Red/Mk-III cam's valve-timing*, along-with lobe-lifts of 11.5 & 9.5mm.
[* related post... viewtopic.php?f=3&t=1614&p=11829&#p11842 ] )
__ Why didn't you share (ahead of time) your intention of ordering a number of such cams to be produced ? _ As I'm sure that others -(at-least Bevel bob), would've been interested in adding to the quantity you're having made !


Hopeful-Cheers,
-Bob

[Bevel bob]

Yes,I am interested in a cam change.I'm surprised to hear that the F1 cam will work well in a 450. I have come to understand that its benefits are realised at rpm's over 9000,not really 450 territory? will the light flywheel of the 450 work with such wild timing at lower rpm's?. My resources are very limited so i have been unable to tune out blowback and subsequent rich running and unreliable tickover,perhaps carb and exhaust changes would help.I'm not 100% sure i'm running an F1 but getting back into the motor soon so will check again.

[DewCatTea-Bob]

[quote= Bevel bob ...
" Yes,I am interested in a cam change. "

____ Glad you've come to confirm you're still interested Bob !
__ Your post has brought-up relevant matters...



" I'm surprised to hear that the F1 cam will work well in a 450. I have come to understand that its benefits are realised at rpm's over 9000,not really 450 territory? "

____ I had already considered adding related info considering such concern,, but chose to for-go doing so, since readers don't seem to appreciate longer posts which are rather filled-up with filler-material. _ But now you've given me excuse to cover that which I previously left-out.
__ You are pretty-much right that a 450 (which has the same in.port size as the smaller engines), can't breath well enough to equally fill it's cyl.capacity and therefore can't rev-up as high as a 250.
You probably read Kev's stated conclusion that the wild G&W.cam would provide his 450 with reasonable street performance. _ Well that's because in order for a 450 to perform as a 450 equally compared as the 250 performs as a 250, then the 450 has to be able to fill it's cyl.capacity to the same percentage as a 250 does. _ But a 450 can't possibly do-so with the same cyl.head-porting ! _ So to help make-up for the short-coming, the valves have-to be held open LONGER ! _ And the G&W.cam will certainly do that more adequately (than the White-cam) !
In a 250, that longer valve-timing 'duration' will allow the smaller cylinder to adequately fill-up even at very-high RPMs when the valves are open for a very-short time, so-thus the smaller 250 will be able to rev-up to over 10k.RPM. _ However a 450 with the same wild-cam, still can't fill-up enough to reach that same RPM.range, so therefore the cam is-not considered to-be as wild within the larger 450-engine !


NOTE... The above response was only about 1/3rd of what-all I had meant to post,, but the rest got lost, and I have yet to calm-down & try to rewrite it over again.
So ya may care to keep an eye on this post for updated wording.







" will the light flywheel of the 450 work with such wild timing at lower rpm's?. "

____ You likely realize that the mag.rotor-flywheel is the same weight as on the smaller-engines, so-then you probably mean the flywheel of the crankshaft !?
__ Anyhow,, the wilder the cam-timing, the easier it is for a flywheel to preform it's intended function at idle, (since there's then less trapped air to compress).
(Kev will also find that kick-starting will be considerably easier with the wilder cam, as well.)


Tillater,
_-Bob

[Bevel bob]

Thank's for clearing that up Bob, Does this cam cause reversion , blowback and richness in your experience, or have i just got the wrong combination of carb or exhaust?.