Without knowing specs on your actual application (stock, mild cam,
Ported heads, headers, compression, etc.) it is difficult to offer
advice unique to your situation. ... now with that said here is some
thoughts ... :-)
In my practice the factory curve provides about 6-8 degrees of initial
timing and have about 15 degrees built into the distributor (at the
crank it doubles to 30 degrees). If you are looking to "wake up"
throttle response a little more initial lead will provide a much
snappier off idle response. Playing with springs and weights will help a
little but really what needs to happen is to limit the advance potential
within the distributor to only about 11-12 degrees (22-24 at the crank)
with 12 degrees initial lead that provides for 34-36 degrees of total
timing (Total timing with all advance in is what the engine sees when
you blast through the gears or are on the throttle) My experience and
everything I have seen indicates that the 302 likes 36 degrees advance
but my Stroker motor with a little longer stroke liked 38 degrees total
the best.
Further tuning of off idle performance can be achieved using the weights
and springs to adjust the rate of advance as it comes it. In my opinion
having the advance curve 'all in' before 3000 is ideal. If the motor is
stock you might want it all in by 2800 with 36 degrees of total timing.
I have not had the stock distributor apart so I can not tell you the
actual steps to limit the advance but it usually requires welding up the
slot to limit the total travel. After you adjust the Total timing and
then the rate the curve comes in THEN work on the vacuum advance but it
will be limited to the amount in the distributor in this case only
around 22-24 available but most driving ... at part throttle cruise ...
involves opening the butterflies a little and it will most always be
less vacuum than at idle or when coasting down hill under deceleration
load with the throttle blades fully closed.
If you are looking at improving the ignition overall the absolute BEST
option is to purchase the new "all-in-one" distributor from MSD. It is a
self contained unit with all electronics in the distributor ...
including the rev limiter. You can adjust both the rate and amount of
advance the distributor will provide.
I hope that was helpful.
Best Regards,
Tim Ronak
Services Consultant
Akzo Nobel Coatings
23961 Via El Rocio
Mission Viejo, CA 92691
Bus: 949-305-5393
Fax: 425-955-6268
Cell: 949-289-3357
email: timothy.ronak@crna.akzonobel.com
Personal email: timronak@cox.net
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