Sam, Not sure if this would help but. I found this one late night of pinz snooping I believe its Dave Ds.
Timing in
Vehicle, mods RPM Degrees BTDC Degrees Advance Inches BTDC
710 Pertronix 800 17 0 0.75
710 Pertronix 2000 35 18 1.04
710 Pertronix 2500 43 26 2.25
712 Stock 800 4 0 0.125
712 Stock 2000 26 22 1.32
712 Stock 2500 31 27 1.75
712 Pertr, Civ cap & plugs 800 16 0 0.75
712 Pertr, Civ cap & plugs 2000 35 19 1.04
712 Pertr, Civ cap & plugs 2500 42 26 2.25
Dave's comments
Because the 710 runs so strong, I used the same base timing for my 712.
Though I haven't checked yet, I believe that the lack of total advance
after the conversion is due to weak springs in the distributor and I'm
getting premature advance at idle.
The truck is running strong and one side benefit is that the truck is
running a lot quieter.
Rob's comments (Stolen from
http://www.dansmc.com/IGNITIONTIMING.html)
For those who are kinda clueless, like me.
When combustion occurs it does not take place instantly. It
requires a period of time. Depending on the RPM the
power stroke can be .05 of a second at 1200 rpm to .0057
of a second at 10,500 rpm. Now even though the time for
combustion at 1200 rpm is not
The reason that this small amount of time is important is
because the combustion process is not as much an
explosion as it is a controlled burning. The time available for
this controlled burning decreases as the rpm goes up. To
compensate for this, the point where the spark occurs, to
start the combustion process, must occur earlier. To
accomplish this weights and springs are attached to the
points cam. As the cam spins on its shaft, centifical force
causes the weights to move and turn this cam on its shaft,
advancing the timing of the spark, thus giving the
combustion process more time to occur as the rpm goes
up. Full advance is usually reached on most engines by
around 3000 rpm.
Most motorcycle engines with points have only a centifical
advance. A few have a vacuum advance. Newer engines with
electronic ignitions usually have an electronic advance.
Some engines have fixed timing with no advance at all. The
lower the compression ratio of the engine means more spark
advance is needed. This is because rapid combustion is
aided by a high compression pressure. Because the
combustion process takes place quicker with a high
compression ratio less time is needed, therefore less spark
advance. Conversely lower compression pressure slows the
combustion process, necessitating more spark advance.
Now why all this about compression pressure and spark
advance? Simply this, as an engine wears out it starts
leaking compression past rings and valves. This lowers the
compression pressure (ratio). What does this mean? You
got it, we need to advance the ignition timing as an engine
ages.
OK...Great...Now What? Well, if the engine is worn, lots of
miles or hard use, we need to advance the point at which
the spark occurs. This works best on large 4-stroke engines
although it can be done on small ones too, but it is harder
to do. I don't do this with flywheel magnetos ( Honda 50's,
70's etc. ) either, because it is a lot of work with that type of
ignition system. On many of the newer motorcycles you
just can't do it without major modification, but on almost all
points ignition machines and a lot of electronic ign. ones
you can.
Now when we increase the spark advance (the point when
the ignition spark occurs, at the sparkplug,
before-top-dead-center of the compression stroke [BTDC] )
we get more power BUT we also get more heat.
There is a point after which we get lots more heat and very
little extra power. We want to STOP before we get to this
point!
The drill is this...With the engine at normal operating
temperature and idling, advance the timing slowly. You will
hear the engine speed up.Move the timing back and forth,
advancing and retarding it till you get the highest engine
idling speed. Then back it off (retard it) just a bit. The
engine speed slows down just a little. You are still idling,
don't touch the throttle.
Go for a short ride and make sure the engine does not
"ping" under load. Then check the color of the spark plug(s)
to make sure it's not running too hot and you are done!
). From what have come across in gasser Pinzes since then, my 710M was an exception vehicle, many other Pinzes wouldn't run without pinging at those advances... and I am sure that on the yahoo group I had said to back the timing to where it would not ping under any condition.