Quote:
Originally Posted by geezer#99
That's close!!
You don't adjust the rotor exactly. You rotate the distributor body clockwise for more advance, counterclockwise for less advance.
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I've worked on only one BBC, but I think it's CCW for more initial advance, CW for less, just like a small block. However, I recently worked on a 400 Pontiac, which is just the opposite, because the distributor is driven by the other side of the cam.
I agree that 12-14 degrees will probably be the sweet spot, maybe even 16. The symptoms of too much advance are:
-- pre-ignition (knocking) on acceleration, especially when engine coolant is up to temp
-- engine turns over slowly when you're trying to start it
Also, make sure there are no vacuum leaks anywhere. Check for cracked hoses, and then suck on the hoses connected to the vacuum advance canister, transmission modulator, any thermal vacuum control valves, EGR valve, etc. to make sure there is resistance. Especially important is the large hose running from the back of the carb or intake manifold to the brake booster.