What's the timing and lift numbers on the RV cam? If it's over a 260 degree total duration, you'll probably experience a little idle roughness. I've been able to smooth out some fairly aggressive can profiles by increasing the initial timing, but it's necessary to limit the centrifugal advance by the same amount, or it will over-advance. For instance, if the specified initial timing is 4 degrees before top dead center, it will idle (and accelerate) better with an initial timing setting of 12 degrees, but the centrifugal advance must be reduced by 8 degrees to prevent an over-advanced condition at cruise speed with its resulting power loss and engine damage.
Some dyno tests we did back in the mid-50's showed that over-advancing ignition timing by one degree after maximum power was achieved resulted in as much power loss as 5 degrees of spark retard from the max-power timing. If you're going to err, do it toward too little advance, rather than too much!
Jerry
