boese1978

I read that all v-8's basically have the dwell between 30-35? Suggestions on how to set for my build? Just 32 or so? how will incorrect dwell angle affect the running?
Thanks for the input!

VC455

Dwell is just the amount of time, in degrees of rotation, that the points remain closed.

If you set dwell too low, the coil will not have enough time to saturate (create its electric field) and the spark will be weak at high rpm.

If you set dwell too high, the coil could overheat at idle because it receives extra current.

When the rubbing block on the points wears, the dwell decreases. That's why some manufacturers recommended a bit more dwell.

GM usually recommended 30°, but there is an acceptable range, as you note.

As well, remember that changing dwell changes the initial timing, so set the timing after you set dwell.

oldcutlass

Acceptable dwell is from 28-32 with 30 being optimum.

MDchanic

As noted, the ideal dwell angle will vary with frequency (engine speed).
This is why the newer computerized ignition triggers vary the dwell with the RPMs.

If you are building this engine to operate within a non-stock RPM band (2,500-6,500 RPM for instance), you may benefit from increasing the dwell angle.

Of course, if you are building an engine to rev that high, points are a lousy high-RPM ignition trigger, so you would be using an electronic ignition anyway.

If you are planning to use it anywhere within the normal rev range, the standard 30° dwell angle should be fine.

- Eric

boese1978

Thanks for the informative answers! knew what the dwell was for, was unclear on the grand scheme of things considering all. swap to electronic down the road, just want to get it running