Race Cams

[Kthomas]

Bob I saw in one of your previous post that the 70 350 WC cam was a racing cam. In your estimation would this work just as well as any of the other ones out there in a 250 with other race components and proper setup ? I have one of these and it would definitely be cheaper.

[DewCatTea-Bob]

[quote= Kthomas ...
" Bob I saw in one of your previous post that the 70 350 WC cam was a racing cam. "

____ Indeed most w-c.350-models (stupidly! *) came with the G&W/250F1 racing-cam (rather than the 350Mk3 or Scrambler cam.models) !
(* When that cam is combined with a muffler equipped exhaust-system,, the result is that not-only is the low-end power greatly lacking std.strength-torque (due-to the wild valve-timing), but-also the otherwise expected tradeoff for increased top-end/high-RPM power fails to come-alive as well ! _ Thus making a Duke-engine a real-dog, overall.)



" In your estimation would this work just as well as any of the other ones out there in a 250 "

____ I really don't have much experience with comparing power-characteristics of aftermarket-cams with any of the D.factory-cam.models, but I'd doubt that any aftermarket-cam offers any worthy performance-advantage over the factory-F1 cam.model,, (which has pretty-much all the same valve-opening factors as a std.DESMO-cam).
__ The main concern with most-all of the non-factory/replacement camshafts, is whether their intended specs are actually as expected (to within a fairly acceptable tolerance-range),, as I've never come-across any aftermarket-cam that met it's claimed specs !



" I have one of these and it would definitely be cheaper. "

____ Then I'd certainly recommend trying it out first, before blowing a relatively high sum of cash for any other camshaft that might not even match it's performance.
__ You could confirm that you really have an actual '250F1-cam' by checking it's particular lobe-lift figures.
Ya-got a good/accurate dial-indicator/caliper ?
__ If you'd care to discover any more about the F1-cam, then you could try reading-through the related past-posts found in this listing... www.motoscrubs.com/forum/search.php?keywords=250F1


Duke-Cheers,
-Bob

[Kthomas]

The cam is out of the head at present. Can't I figure out the lift by subtracting the smaller lobe dimension from the height of the lobe and then multiplying by the rocker ratio ? What is the rocker ratio on these ?
thanks

[DewCatTea-Bob]

[quote= Kthomas ...
" Can't I figure out the lift by subtracting the smaller lobe dimension from the height of the lobe and then multiplying by the rocker ratio ? What is the rocker ratio on these ? "

____ The 'rocker-ratio' (which I was informed by a top authority is "1.04:1") is irrelevant for cam.model identification, (but could be used for calculating the actual 'valve-lift').
__ As for obtaining the lobe-lift figures,, while your stated wording really doesn't say what you must've actually meant, I still think you seem to understand what you actually need to do in order to measure-out the 'lobe-lift' itself. ...
More thoughtfully worded,, in order to figure-out the lobe-lift dimension, the dimension of the 'base-circle' (of the 'cam-track') has to be subtracted from the overall-dimension of the entire cam-track (which is the maximum-distance that includes the most outer-extremes of the 'base-circle' plus the 'lobe-peak' of the whole 'cam').
So in detail,, the minimum-diameter of the cam-track's base-circle must be found & measured, and the TIP-to-TIP maximum-dimension of the overall*cam-track (* from lobe-peak to 180-around) has to be located & measured as-well. _ And any follower-face path wear on the cam-track surface should be avoided, by relegating your measuring-device to reading just the unworn edge of the cam-track.
__ Even-though the base-circle & overall-cam dimensions can vary somewhat between same cam.model production-batches, the end-result 'lobe-lift' figures always turn-out correct for identifying any particular cam.model.
So after you've obtained your min & max cam-track readings (within a couple thousandths tolerance), I can then identify which cam.model you happen to actually have.


Dukaddy-DUKEs,
-Bob

[Kthomas]

Here are the numbers I got roughly. 20.73, 29.29 and 20.91, 30.79

[DewCatTea-Bob]

Here are the numbers I got roughly. 20.73, 29.29 and 20.91, 30.79

____ Your first listed pair of figures must've been taken from the exhaust-cam and the second pair from the intake-cam,, as the resulted 8.56mm & 9.88mm lobe-lift figures are about as expected for exhaust & intake respectfully, (for a 'Green&White-camshaft').
However, it seems that it's not real apparent whether your cam.model is a '250F1' version or rather actually a '350Mk3' cam-model. ...
__ The 250F1-cam usually has an intake-lobe lift-height of near-around 9.85mm, with it's exhaust-lobe's more-like 8.35mm. _ While the 350Mk3-cam has rather higher lobe-lift figures near-around 10mm & 8.5mm (in. & ex. respectfully).
Since cam-lobes can certainly wear-down but of-course can't grow-up any taller than original-height,, your measured ex.lobe-height well indicates that your (G&W-coded) camshaft must be a 350Mk3-cam.model, (apparently with a slightly worn intake-lobe).
So does your intake-lobe show any signs of wear (that's not so as apparent on the ex.lobe) ?


Duke-Cheers,
-Bob

[Kthomas]

That's correct. The first numbers was from the exhaust cam. I think I am going to use it as opposed to paying upwards of 400.00 for one.

[Kthomas]

As to the wear and accuracy of my measurements my calipers are of the cheaper variety . This cam didn't look worn at all . I have another cam which looks the same but is worn quite a bit. Its measurements are 20.57, 29.13 & 21.00, 30.87 Again my calipers are not the best. Thanks for all your help.

[DewCatTea-Bob]

[quote= Kthomas ...
" I think I am going to use it as opposed to paying upwards of 400.00 for one. "

____ That's a fairly-good decision to choose, as the 250F1-cam merely offers only more 'overlap-duration' (than the slightly milder 350Mk3-cam).



" This cam didn't look worn at all . "

____ I can believe that, as I think I recall of another 350Mk3-cam.example also having only near-about 9.9mm of in.lobe-lift.
__ The only other (and more difficult) method for differentiating the two G&W-cam.models, is to check the closing-timing of the ex.lobe, (as the Mk3-cam closes the ex.valve quite notably sooner).



" I have another cam which looks the same but is worn quite a bit. Its measurements are 20.57, 29.13 & 21.00, 30.87 "

____ Seems to also be the same cam.model,, and that your measurements still indicate no appreciable wear, apparently means that you must've successfully taken your size-readings right-on the unworn edges of the cam-lobes.
__ Do the worn lobe-tracks have in excess of .5mm of wear ?
____ Do you have the cyl.heads that your two G&W.camshafts came from ?


Dukaddy-DUKEs,
-Bob

[Kthomas]

There is very little wear on the cam that has wear. The wear is on the ramp of the exhaust cam. Both cams came from 69 or 70 WC 350 scramblers.
One head is off to be flowed .