Norris Cam and Regrind Questions

gortnipper

VIP MEMBER
Joined
Nov 11, 2013
Messages
2,885
Country flag
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.
Well, that sluggishness has nothing to do with the 2s cam.
 

comnoz

VIP MEMBER
Joined
Dec 10, 2008
Messages
7,193
Country flag
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.
P1020983.JPG
 

comnoz

VIP MEMBER
Joined
Dec 10, 2008
Messages
7,193
Country flag
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.
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.
 
Joined
Apr 27, 2015
Messages
1,417
Country flag
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.
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...)
 

comnoz

VIP MEMBER
Joined
Dec 10, 2008
Messages
7,193
Country flag
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...)
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.
 
Joined
Nov 26, 2009
Messages
2,270
Country flag
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...)
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:
Joined
Dec 23, 2010
Messages
631
Country flag
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.
Jim ,
Could the same thing work for a Maney cam which I believe is more or less the same as a 4S ?

Martyn.
 

comnoz

VIP MEMBER
Joined
Dec 10, 2008
Messages
7,193
Country flag
Jim ,
Could the same thing work for a Maney cam which I believe is more or less the same as a 4S ?

Martyn.
Actually the Maney cam is a 2s combat cam. It will help to advance it with low compression.
 
Joined
Dec 23, 2010
Messages
631
Country flag
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.
 
Joined
Apr 15, 2009
Messages
10,192
Country flag
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.
So 9 links instead of 10?
 

comnoz

VIP MEMBER
Joined
Dec 10, 2008
Messages
7,193
Country flag
So 9 links instead of 10?
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.
 
Top