13
Mark 4.
= ( ) TDC on the rear cylinder.
This mark is rarely used for ignition timing
and is only listed as a reference for professional engine
builders or when checking timing on the rear cylinder with a dial back type timing light.
Range of timing hole
: Shown with Mark (2). When timing an engine with a 30˚ mark on the flywheel, if the mark is to the front of the hole the
total timing is
R
etarded to 26 degrees. If the mark is to the rear of the hole the total timing is advanced to 34 degrees. When in the center of
the hole this mark represents 30 degrees of advance for the front cylinder. This can also be useful when using certain ignitions on larger
engines where the slowest curve still advances the timing past the recommendations below. Many Electronic Ignitions have good curves but
with too much total timing. You can retard the base timing and change the entire curve by moving the TDC mark to the
R
etard side of the
timing hole prior to the static timing process to make the advertised curve produce the desired total timing. When setting the timing on any
engine we recommend using a timing light to verify the ignition timing is accurate.
Initial timing of the ignition system
Engine Displacement
96”
Total Timing @Full Advance
32-34
With the variety of ignitions available it is difficult to explain this process for all ignitions.
If you do not have instructions for your ignition
please contact the manufacturer and get this important information.
Some of these are listed at www.ultimaproducts.com.
On ignitions such as Ultima
®
, Crane, Dyna 2000 and Compu-Fire that have adjustable advance curves, do not select the most aggressive curves
for break in. On some Ignitions only a few curves offered will provide the proper timing at full advance and some will advance more than 26-28
degrees on the least aggressive curve.
If you cannot get the full advance timing needed, shown in the chart above, you will need to retard the
base timing the amount needed or replace the unit with one that has the proper total timing at full advance..
We have found in most cases
these Ultima Shovelhead engines will accept full timing before 2500 rpm and this is the best choice for most engines. If you have excessive
Spark Knock or detonation go to a slower curve, Colder Spark Plug, Richer Jets or better fuel. Whatever tuning you need to do to get rid of this
condition must be done. Higher elevations typically require more advance timing than lower elevations. Use the chart above for the range to
stay within.
If you have any doubt that your timing is not set correctly or that your ignition system may be faulty have it checked by a professional Mechanic
and bring this booklet in for their reference.
After your engine’s break in procedure has been strictly adhered to we recommend that you have your engine dyno tuned with
timing and advance curves set for optimum performance and reliability.
