quote:Originally posted by DeTom:
...George, one more cam question...
No, you've asked two questions my dear friend.
quote:...Can a dual plane manifold live with more duration than a single plane...
The more a motor's powerband extends beyond 5000 rpm (therefore more camshaft duration), the more a single plane intake manifold will complement the motor. It makes absolutely no sense to design a motor with a powerband of 4000 to 8000 rpm and equip it with a dual plane intake manifold in an attempt to make the motor idle at a certain low rpm. The dual plane intake manifold is robbing too much torque from such a motor. It is better to just raise the idle rpm of the motor and equip the motor with a single plane intake manifold.
A powerband of 3000 to 7000 rpm is a fence straddler, there is as much powerband below 5000 rpm as there is above 5000 rpm. This is the rpm which the cast iron Cleveland 4V heads naturally want to operate at, when set atop a 350 cubic inch motor. The Blue Thunder intake manifold was designed to straddle the fence as well as a two plane intake can, with an emphasis on lower rpm operation (street use). With a properly set-up carburetor, the Holley Strip Dominator and the Parker Funnel Web 4V intake manifolds straddle the fence just as well, with the emphasis shifted to performance at higher rpm.
Truth is, a 350 cubic inch motor will be significantly better off on the street with 2V heads and one of the 2V intake manifolds (Edelbrock Performer, Edelbrock RPM Air Gap, Parker Funnel Web 2V).
quote:...If you didn't care if you had any vacuum at all, say you had no vacuum advance, and no vacuum assist breaks or anything, how much duration could you safely go with...
What is meant by "safely"? A cam can be ground to achieve a x type powerband, x type idle characteristics at x rpm, x type drivability characteristics, to work in conjunction with x gearing and with a car weighing x pounds, transmitting its power through a x type transmission, with a motor burning x type fuel, with x type cylinder heads, x compression ratio, x type intake system and x type exhaust. Fill in the "x's".
cowboy from hell