cam sprocket question

jensen · Post by **jensen** » Mon Apr 11, 2011 5:14 pm

Hi,

Can anybody explain me what the differences are between a C72 / 77 and a CB72 / 77 cam sprocket other then the length of the advancer weight arms and advancer springs ? (and another function of rpm versus advance timing).

Did anyone used a C72 / 77 cam sprocket in a CB72 / 77 (or the other way around) ? and what are the experiences ?

Jensen

jensen · Post by **jensen** » Tue Apr 12, 2011 3:56 pm

Hi,

I can't find any other differences then I mentioned earlier.
See the pictures for references.

Jensen

jensen · Post by **jensen** » Tue Apr 12, 2011 3:58 pm

Hi,

And, o Yes, look at this.
Pictured are the threads of the cam sprocket,
one "normal"left threaded, and one "abnormal" right threaded

The abnormal right threaded is from a "heavy"cam sprocket, also pictured.

Jensen

jensen · Post by **jensen** » Tue Apr 12, 2011 4:08 pm

Hi,

I think these sprockets can be used in both applications, and probably the dream sprocket is quicker in giving full advance. LM and I agreed on that, any other interesting input ?

I think it's kind of stupid (but challenging) trying to answer your own questions, isn't it ?

Jensen

jensen · Post by **jensen** » Tue Apr 12, 2011 4:11 pm

Hi,

Would the heavy cam sprocket have been engineered for softening the vibrations ?, as a counter balance ? A first order or the second order balancing weight ? Anyone any thoughts ?

Jensen

G-Man · Post by **G-Man** » Tue Apr 12, 2011 4:40 pm

Hi Jensen

I noticed the right hand thread on my early Dream camshaft but I hadn't looked at the governor weights which your picture shows so well. The Dream weights have extra material so they will advance the timing more quickly than the CB weights which are shorter.

I don't see how that big cam sprocket can act as a balancer as it only runs at half engine speed.

Incidentally, this reminds me of the English saying "Going balls out" to imply as fast as is possible. This saying comes from steam engines where the governor is made up of heavy balls acting on the steam regulating valve.....

It would be interesting to spin those cams in a rig and observe the motion with a strobe light. Those camshafts are just so much more complicated than they need to be as shown by later Honda cams and advance mechanisms.

G

teazer · Post by **teazer** » Tue Apr 12, 2011 9:50 pm

But impressively clever for the time.

Compare that design to say a BSA of the same period........................