Just installed my Cirello remanufactured mag (8R101). It started my 59ab right up, but it seems to run "flat". My timing light shows the timing retarded from TDC and increases across the rpm scale. Am I going crazy or am I missing something. Could this be a reversed unit? Is there a quick fix? I called up Tom Cirello, but didn't get an answer. Thanks!
Since there's no internal advance sytem inside the H&C mag where its set initially on the front of the engine is where the timing would remain. My bet would be the timing light your using is being effected by the mag signal causing the poor reading. You mentioned it seems to run flat that's typical of the H&C mag to get the engine to run it needs to be set with little advance. You should really have an advance plate under the mag that will help greatly in getting the ignition where the engine is happy under load. Your initial setting should be from 8 to 12 degrees advance for good throttle response. BUT the problem with the H&C mag to get the engine running really well under load you need a total advance to be around 22 to 25 degrees there's no way to fire the engine with the timing set that high. All the above is what I have experianced tuning engines using the H&C mag.
Thank you ronnieroadster! Wisdom like yours is what makes this forum so great! The light Im using does contain some internal components which could be effected by the signals coming from the mag. I'll have to find my old hard wired light and I'll let you know what I find.
My Vertex mag did the same thing to my dial back timing light. drove it completely insane. Your old hard wired light will tell the truth. Ronnieroadster says there's no advance in yours, so I'm not sure how to solve the problem of needing 22-25 degrees to run, but only 12 to start. A modern drag racer's timing retard box of some kind?
One of the tricks from the old days to start an engine with a magneto without centrifugal advance but running a fair amount of static advance was to spin the engine with the mag switch 'off' (no spark) then flip the mag 'on' after the engine made several revolutions. Worked best on an engine with a 6 volt starter running on 12 volts......if you still got 'kick-back' you had to retard the timing by a couple of degrees. Not a clean solution but it helps
Well the timing light did the trick! I've heard the old timers used to use a timing plate and by running it loose they would run a cable from the driver to the timing plate. Basically like an old Harley, they would adjust the timing manually on the fly.
That's good news the mystery is solved. The timing plate would certainly make the use of the mag more enjoyable. Having an adjustable cable in the car connected to the movable section of the plate should work. If I was doing it I would use a cable that has an adjustable knob similar to what's used on hydraulic plow controls by turning the knob the adjustment stays in place this would work much better than say using a choke type cable. If you need an adjustable plate I have one its identical to the type Offenhauser made years ago but no longer offers. Ron
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