Jumper or No Jumper on P-Mags

[Dean Pichon]

Mattituck installed a set PMags in my engine and ran it in the test cell. I assume they did so without using the jumper described in the installation manual as no jumper was present on the mags when I received the engine.

I am reluctant to do anything to change what Mattituck assembled/tested, but notice the PMag installation manual suggests using the jumper.

Can anyone provide some addtional info to help me make the decision regarding whether or not to install the jumper at this point. E.g. Why is the jumper recommended? Would Mattituck have reason to run without the jumper, or did they likely remove it?

Thanks,

[N941WR]

From the E-MAG Ignitions manual:

Variable Timing Limit:
The ignition will use engine rpm and manifold
pressure to calculate firing angle over a range of
operating conditions. There are two preprogrammed
curves that can be called up by the operator by using
a jumper between thermals #2 and #3. The ?B? curve
will allow timing to advance as much as 39 degrees.
The ?A? curve will allow timing to advance as much as
34 degrees. We recommend starting with A curve.
? A Curve advances (up to 34 degrees) - WITH jumper.
? B Curve advance (up to 39 degrees) - NO jumper.

Your choice, putting the jumper in will dial back the power a little but I doubt you will notice it. You might, who knows. Either way, it won?t hurt to try it.

Check out the manual and the graph where it shows the timing shift, it is down around page 17, depending on which version of the manual you are reading. That should help you make up your mind.