Quote:
Originally Posted by Bezant
I used the vacuum method and ended up going to -10 (-20 with the distributor vacuum disconnected). No pinging so far on 87.
My mechanical advance was only going up to -30 though.
It's in the bottom of the distributor right? Is it most likely just gummed up? Any advice on that job?
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B:
The use of a sign(-) is a bit unconventional. The ignition firing point is usually designated as being Before Top Center (BTC), or After Top Center (ATC). We could assign a + sign to firing BTC, and a - sign to firing ATC.
Since it is not likely that the firing point retarded (movement ATC or -), your result of movement from 20 to 30 with increasing RPM should be understood as advancing from 20 degrees BTC to 30 degrees BTC.
A vacuum peak at 20 deg BTC is not a surprise; failure of the centrifugal mechanism to advance past 30 deg BTC @3500 RPM is a surprise. Did you check for free movement of the rotor as was suggested in a prior post? The rotor should rotate smoothly about 10-15 degrees CW with finger pressure, and then snap back when released.
It would be helpful if you could post a couple of pics of the distributor from different angles.