'65 CS cams

[Red Gauntlet]

The cams and pinion on my '65 G80CS are well worn pn's 030202 Inlet and 030205 Exh (Norton pump) does anyone have the correct timing for these so I can match the profiles, many searches reveal the SH timing but not the later cams.

[Joker_Bones]

The G85CS-G80CS-P11 Scrambles Motor Cycles Instruction and Maintenance Manual gives these values...

1967.jpg

Pretty much the same as SH? except no valve lift is quoted.

[ajscomboman]

The cams would have been CI and CE type, however they wear out very fast if not run at full chat all the time. Ken De Groome only recommends fitting those cams if you're going to use the bike as intended and race it! For use on the road and general riding with mates then SH is the best cam to fit, even then he advises not to let the motor chug along!

[Joker_Bones]

The part nos. given by RG are for '64 on G80CS and G85CS cams.
The valve timings for CE and CI cams given in Neill do not tally with the values given in the G85CS and G80CS manual above.

CE CI.jpg

I have no first hand experience of any of these cams, both of my compy engines have ordinary H cams in them, just looking at the figures out of curiosity.
I have read what Ken de Groome says about the 'hot' cams making short life of the cam followers.

[Red Gauntlet]

Thanks for the info, I am not sure the cam timing is the same for the '65 engine, I will get a degree wheel and check it on the weekend. At least I have a starter to compare, and yes I had changed the followers as they had worn badly, sadly the cam profiles are worn too hence the reason for change, anyway the followers are a lot cheaper and more obtainable than the cams so I will leave as is until a new set of cams come along, then I will swap the whole lot out.

[mdt-son]

Have you asked Ken De Groome for availability of replacement cams? He used to make new camshafts for the 500CS.

As for camshaft lift and duration, the presented data indicates lift and duration is measured at the valve stem tip. If so, be sure to use a rocker box with the short inlet rocker arm specified from 1963 onwards. It will amplify the camshaft lift, but requires lift to be re-calculated for a comparison with 1960's cams. Crankshaft angle at which valve is .001" off its seat will be slightly affected too.

While re-designing the 500CS for 1964, AMC should have incorporated pivoting cam followers, similar to the lightweight range and the twins (Velocette used this design as well). They will permit high lift cams to operate without their feet digging in, and they are much lighter than the traditional follower design.

- Knut

[Red Gauntlet]

Yes it has the short rocker arm, I think some cams may be available later in the year. I will check the timing with a dial indicator at the crank case mouth, it will give a good enough indication and a lot less hassle than trying to do it at the valves. The engine is full race with polished flywheels, triple row big end, Carillo con rod, billet forged piston, roller mains etc.

[mdt-son]

Hi RG, did you measure lift of the cams? And do you have figures for the rocker ratios (post'62)?

- Knut

[Red Gauntlet]

Hi Knut, I did but have mislaid the piece of paper, when I get a chance I will dig it out, probably Friday.