Norris Cam and Regrind Questions

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Ron L said:
I have a 2S in my '74 850 Interstate that is otherwise stock. Runs fine, good freeway power with a 22 tooth gearbox sprocket. A little sluggish at low rpm compared to my 19 tooth 750's, but quite tolerable.
Click to expand...

Well, that sluggishness has nothing to do with the 2s cam.
 
And here are two Norton cams that give exactly the same motion at the valve.
The left is made for 7/8th radius Triumph follower and the right is for a flat Norton follower.
Norris Cam and Regrind Questions
 
Ron L said:
I have a 2S in my '74 850 Interstate that is otherwise stock. Runs fine, good freeway power with a 22 tooth gearbox sprocket. A little sluggish at low rpm compared to my 19 tooth 750's, but quite tolerable.
Click to expand...

If you want to liven up the lower end when using a 2s cam on a low compression motor then re-mesh the cam gears to advance the cam 5 degrees. [or more]
It helps get back some of that grunt you lost between 3 and 5000 rpm.
 
comnoz said:
And here are two Norton cams that give exactly the same motion at the valve.
The left is made for 7/8th radius Triumph follower and the right is for a flat Norton follower.
Click to expand...

Given that the 2 cams transmit the same motion to their valve train, does either cam/follower set up wear significantly better than the other? ... and if so why... (yeah, I got questions...)
 
o0norton0o said:
Given that the 2 cams transmit the same motion to their valve train, does either cam/follower set up wear significantly better than the other? ... and if so why... (yeah, I got questions...)
Click to expand...

No, they seem to wear the same. This is a relatively mild street grind.

If it was a big race cam like a Norris D grind or bigger then there may be a wear advantage due to the lighter Triumph follower.
 
o0norton0o said:
Given that the 2 cams transmit the same motion to their valve train, does either cam/follower set up wear significantly better than the other? ... and if so why... (yeah, I got questions...)
Click to expand...

Axtell#3 cams didn't have a lot of lift and they were available for flat lifters as well as radiused lifters. Some racers tried them both. A flat lifter Axtell cam looked beat up after a season. A radius lifter cam with the same valve action looked better with less wear. You had the choice of a pointy nose cam shape wearing on a flat surface lifter or a roundish nose cam wearing against a roundish lifter.
 
Last edited:
comnoz said:
If you want to liven up the lower end when using a 2s cam on a low compression motor then re-mesh the cam gears to advance the cam 5 degrees. [or more]
It helps get back some of that grunt you lost between 3 and 5000 rpm.
Click to expand...

Jim ,
Could the same thing work for a Maney cam which I believe is more or less the same as a 4S ?

Martyn.
 
Thanks Jim, I'll give it a go on my 750 which I have always found a bit lacking at lower revs. Steve insisted that there was no need to alter it from the standard setting. The engine has a stage 1 head job & the CR is 8.7 : 1 if I remember correctly.
 
comnoz said:
If you want to liven up the lower end when using a 2s cam on a low compression motor then re-mesh the cam gears to advance the cam 5 degrees. [or more]
It helps get back some of that grunt you lost between 3 and 5000 rpm.
Click to expand...

So 9 links instead of 10?
 
swooshdave said:
So 9 links instead of 10?
Click to expand...

No, you would go 11 links and then go forward 3 teeth between the crank and intermediate.
1 chain tooth is 15 degrees and three gear teeth is 17.5 degrees. So that gives you 2.5 cam degrees or 5 crank degrees of advance.
 
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