Need Volvo 570 Timing Term Explanation

[rdc54yty]

Engine is 1993 Volvo Penta 570 MS4, Prestolite Electronic Distributor w/Mech. Advance

Nothing is wrong, engines run, I want to time them and don't understand the service man terms of initial timing and final timing (at 3000 RPM)

1. Is initial timing at idle the "set to" value?
2. Is final timing what should be observed at 3000 RPM (assuming advance, distributor, timing gear are working well)?
3. If observed final is wrong, are there other causes?
3. Since this is a mechanical advance, does it matter if timing is done under load or at the pier?
4. Can a substantial error in the distributor sensor gap affect the timing (like dwell)?

Thanks in advance, this a great forum..

 

[mkast]

Re: Need Volvo 570 Timing Term Explanation

Initial timing is X number of degrees Before Top Dead Center.
At idle, engine at operating temperature, usually in gear to get the correct engine RPM, as stated in service manual.
Total timing is initial timing degrees plus advance degrees, usually around 3,000 RPM. Most advance degrees are in by that RPM.
Mechanical advance in a 1993???
Mechanical advance uses springs to move the plate in the distributor.
Corrosion is the usual suspect.

 

[rdc54yty]

Re: Need Volvo 570 Timing Term Explanation

Thanks. Just to be clear..

Time it at idle in gear to spec'd initial timing value (I think it's 6 or 8 BTDC), then check it at 3000 RPM against the spec'd total timing value.

Yep, it's a mechanical, has weights, springs, not vacuum pot. It's a Presto IDU 7802A.