Very basic camshaft question

Hello Gents,

Just looking at different cam choices for pepping up my mk3 850, but thought I would first get the factory cams clear in my own mind before I think about changing them (Part numbers from Andover Norton website)

2S 063536 is the Combat cam?

3s is ???

4s 063536 is ??? racing cam?

Std MK3 cam is 061084- some of which wore out prematurely- can this be assessed without dismantling the engine?

Oh and if anyone knows which 850 had the RH9 'High Performance' head and how it differs to the RH4 it'd be very happy to know.

Lastly, which book would you recommend as a good Cdo development history, which would tell me these things?

crusadersports said:

Just looking at different cam choices for pepping up my mk3 850, but thought I would first get the factory cams clear in my own mind before I think about changing them (Part numbers from Andover Norton website)

2S 063536 is the Combat cam?

3s is ???

4s 063536 is ??? racing cam?

Click to expand...

http://www.nortonownersclub.org/support ... /camshafts

crusadersports said:

Std MK3 cam is 061084- some of which wore out prematurely- can this be assessed without dismantling the engine?

Click to expand...

You could measure lift at each valve (with a dial gauge) and check for any discrepency.

crusadersports said:

Lastly, which book would you recommend as a good Cdo development history, which would tell me these things?

Click to expand...

There isn't any actual definitive publication, however I would recommended the following books:

Norton Motor Cycles from 1950 to 1986 - Steve Wilson (out of print)
Norton Buyer's Guide - Roy Bacon
Norton Twin Restoration - Roy Bacon
Norton Commando - Mick Duckworth

Go here... http://atlanticgreen.com/nhth.htm for the head info.

Std Commando is ' S S " Dominator grind . May be someones SS grind ' magneto ' cam IS a Domi cam , so std. Commando .

' S S ' Commando is Early ' PR ' cam . ( Fastback based production racer )

' S S S ' ( 3S ) is really ? F-750 cam from around 72 . Said to be peaky .

' 4 S ' cam is late fancy race grind , said to be wider powerband and torqueier than 2S & 3S .

Due to samping , ' S ' & ' 3 ' CAN be confused , as its across or along the radius . The THREE stamp has the V top C low ,

in letter form , ( top cnr, Rt , Down to left , half loop around 0 Not two C's one above the other)
SO the 3 ISNT two C like the S but hard straight lines on the top of the letter, may help someone.

As ' Someone ' got a S S said to be a 3S , Timed approx 5 deg early , a attempt to achive 3S tdc figures ,
gave a good two stage effect , wakeing up around 3000 , on the boil firmly at 4000 and no stopping it .

4S was in PR by 72 .

Some of the American Camshafts me be higher spec material ( ( than ) Quenched cast iron ? ? ) and accurate form .

Regrinds can be hidious . Id wasted $ 160 on two , measurements across flanks & heal to lobe were irregular .

G'day Crusader,
I am very happy with the characteristics of the 4s, that I put in my Combat. The power is very broad,
just like a 4 speed long stroker should be.
The valve clearance is quoted as 14 - 16 thou on both inlet and exhaust which is a bit rattly.
Ask Peter Williams, and Jim at JSMotorsports, about their cams and valve clearances, you might get the same
type of power with a quieter engine.
AC.

" some attention " should be paid to the Valve Gear , when fitting these high faluting Camshafts .

SEE the MANUFACTUROR s ( off the bump stick ) Recomendations . ( springs , Clearances Vs coilbound / spring hight etc )