I have a summit 1107 cam in a 327 and am trying to dial in the timing.The manual says my timing should be 4 degrees BTDC, of course thats for a stock cam so thats out the window.The car wont run with it set there. It runs good with about 30 degrees at idle but that sound like a lot.Should the info on the cam card give me a clue where my timing should be?Thanks.

Cam companies don't normally include any ignition timing specs due to the large variance in motors the cam may be used in. What's the rest of the motor like in your case?

While cams affect timing in the sense that they affect volumetric efficiency, and cylinder pressures, as well as idle quality, they are really kind of independent of ignition timing - stock vs. hot may, or may not, be very different. With a certain cam you may have to back off the timing a bit to reduce the tendency toward detonation, but this probably won't be the wildest, or the mildest, cam.

What you generally want is 32 to 38 degrees total mechanical advance. So your initial timing (with the vaccuum advance disconnected) plus your mechanical advance should be 32 - 38 degrees, depending on what your engine likes (no detonation). With an HEI, for example, which has about 18 to 20 degrees of mechanical advance, this means an initial advance around 12 to 18 degrees (again, vaccuum advance disconnected). You want all the mechanical advance to be in by 2500 to 3000 or 3500 rpm (lower end for a manual; higher end for an automatic). An adjustable vaccuum advance is really what you want to tune it. You set the mechanical and initial per the above parameters, back way off on the vaccuum and hook it back up, and verify that you don't get detonation under full throttle. Set it as far advanced as you can, but a couple degrees before you notice detonation, and no more than about 38 degrees total mechanical. You may find it accelerates best with even a little less mechanical timing than this...but that's fine tuning.

THEN you start increasing vaccuum advance 'til you get detonation under part throttle load (up a hill, not too much throttle, so the vaccuum is maximum, but the engine is loaded; or part throttle acceleration). Once you hit detonation, back off a couple degrees.

This approach is generally the way to do it, regardless of cam. And no one can tell you how to set it for a specific cam, or any other specific component, either. Any adjustable vaccuum advance kit should include these same basic instructions.

With the vaccuum hooked up at idle, you may well end up well into the 20's once the engine catches and idles, and at 3500 rpm under light throttle you may be well into the 40's toward 50 degrees total...but you should never be setting your timing this way.

The mechanical advance is set up for full throttle performance. The vaccuum adds more advance to improve part throttle efficiency and performance. For a street car you want both, for a race car you probably want only mechanical. (Though if it does dual duty you still want both.)

Good luck!

Thanks for the info, here is the combo - 327 .30 over, flat top pistons, summit 1107 cam(234/244 duration, 488/510 lift.) HEI, Performer RPM intake, edelbrock 600 CFM carb, Pro Lightning heads (180, 64cc) & Headers and the car is a 4 speed.Thanks