Camshaft question

James Clews said

When I put my 318 together it was sending the plugs black even though I had the mixture screws in the best spot. I had idle timing set at 12 degrees. It wasn't until I adjusted the idle timing to 20 degrees that it cleaned up the plugs and made the low end response a lot better. The camshaft is a 204/214 @ 50 thou , so not a big cam.

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That cam shouldn't need 20 degrees of initial timing. As an example a 256 @ solid cam with 320 adv duration making 9 inches of vacuum with a 108 LSA needed 22 degrees of initial timing.

Bewy said

So check the timing, in gear, & report back [ hint: it may not be this much now, but it might want 40*..or more ].

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Neither should it need 40 or more. Every degree before TDC you ignite the mixture is wasted energy not applied to the crank when it can translate to forward motion. High Idle timing is a function of too much overlap and too much exhaust residual in the chamber requiring earlier ignition because the mixture is diluted or lean. LEAN MIXTURES BURN SLOW!!!!!!