Ignition timing 48 Cub

Thu Jul 11, 2013 1:47 am

Andy here from the UK.

Planning this weekend to set the timing on '48 Cub with Magneto ignition. Slight confusion on this aspect in the manual.

Can you please provide from your practical experiences the best points gap and timing marks with use of strobe light?

Grateful as ever. Andy.

Re: Ignition timing 48 Cub

Thu Jul 11, 2013 2:05 am

Strobe light may not be any help unless it has a built in light advance/retard function. Once the tractor fires up, the mag goes full advance to 13* BTDC at all throttle settings, so it won't ever flash with the needle and timing mark aligned. It will always flash with the needle 13* ahead of the pulley mark.

Pull the cap and ensure the rotor line is aligned with the pinion line. Point gap is .013"

What I would do is rotate engine to #1 cylinder TDC on compression stroke and align timing mark with the needle. Loosen the mag and rotate it towards the engine block all the way. Rotate engine one revolution till timing mark is aligned again. Then slowly rotate the mag away for engine till the impulse spring trips. When the spring trips, tighten the mag back down and call it a day. Really no need for a timing light unless just for gee-whiz factor.