Pulling Timing Gear with Aux Housing in place
 

Guys,

I need to pull the timing gear for my Bendix mag out and don't want to take the accessory housing off.

Quick background it my motor is running great on the electric mag but when I test the mech mag it back fires and quits. I checked the timing of the mech mag and it is so far out I can't get it back as the required rotation of the mag for timing causes it to interfere with items in the center of the accessory case.
https://photos.google.com/photo/AF1Q...RuEB_q5ML1bpp4

https://photos.google.com/photo/AF1Q...0JlGO4x-4pl60S

I am sure the gear is in the wrong position and needs to be pulled and rotated but it is in there pretty good and I am reluctant to try to pry it out.

Any suggestions?

Thanks

Mike
40644

Mag overhaul
 

If your engine has been running and not a receint build it is not likely that the gear jumped out of position. I would bet that the internal timing is off due to wear. I suspect that it is time for an overhaul.

Gary

I agree with Gary - this is one of those cases where you think you might be saving time by not pulling the mag out, but in the end, you'll create a much bigger job by not doing so. If it were me, I'd pull the mag and work on it on the bench. I've taken the long way by trying shortcuts way too many times.

On my engine (IO-540), the mag timing gear was easily removed/replaced through the accessory case hole that was opened up by removing the mag. On my engine, there are two rubber cushions in the mag drive gear that need to be accounted for.

A few thoughts...... some good advice from others here. The mag is your problem, or the way you are installing it on the engine. The timing gear is NOT the problem. Be sure you are setting the timing of the mag correctly on the bench and THEN make sure the engine is at the specified timing, usually 20 or 25 degrees BTDC before attaching the mag to the engine. I have seen people set the engine at TDC when installing the mag, and then it is impossible to time it correctly. This may be your problem.

IF you do remove the engine gear, be sure to place a rag underneath it inside the accessory case. You don't want the rubber cushions falling into the engine, and there is a bearing that is press fitted into the crankcase that SOMETIMES comes out with the gear and other times it doesn't. You don't want it falling into the sump either.

Vic