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CB750K vs CB750A points plate and advance mechanism- Interchangeable?

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Yamahawk:
Hi again,
   I helped a friend of mine replace a burnt up Dyna ignition with points on a 1973 CB750K, and we robbed a 1976 CB750A model of its advance mechanism, and points plate. I noticed a different number on the CB750A plate, 333 vs. 300 on a CB750K model plate. We used the 'A' model as the cam was still on the advance mechanism, and the parts were all from the same bike. The CB750A is a 1976, and the bike is a 1973 that we installed it into. I static timed the points, and we didn't have time to fire it up last night. We also kept the green Dyna 3 ohm coils. Is there any incompatibility here? Thanks!
Charlie

Bryanj:
Advance curves may well be different as the A model was a softer state of tune but the bike should run, the 3 ohm coils will draw more current than standard ones and as such the points won't last as long but again should run

AshimotoK0:
Points plate for Auto is still a 300 part but auto advance is a 333 part (same as CB350F/400F as is the points plate, i.e 333 part ref. )

Yamahawk:
Thanks, Brian and Ashimoto!
   I guess it was the advance plate that had the 333 on it, would there be an issue running that advance plate? Is it just the springs that may be a different stiffness, or do the weights have a different mass to them also? We used the CB750A advance mechanism because they had removed the cam from the other one to run the Dyna rotor. Not sure if the CB750A advance comes in sooner or later than the CB750K model.
I believe the stock coils run 5 ohm, so yeah the points will pass more current, and arc out sooner with the 3 ohm Dyna coils. Bit, it may give a healthier spark, too!
Charlie

K2-K6:
It looks like the 333 advance comes to max later. The auto may have used this to soften the change up torque on the 750A during lighter throttle loadings so that they could use a slightly longer clutch engagement to smoooooooth it through when cruising.

It shouldn't really hurt the manual installation you've got but may make it slightly less economic during lower rev light throttle cruising. Certainly wouldn't give you a technical or durability problem as I see it.

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