Substituting Slick 4347 for Slick 4370

I have an RV-6 with 900 hrs tt on airframe and engine. Recently my RHS Mag failed, and by my reckoning it has an open secondary winding.

Originally the RV-6?s engine had Slick mags on both the LHS and RHS. The LHS Mag was a model 4347 with a retard breaker that was energized with a vibrator to start the engine. I later replaced the LHS mag with a PMAG and put this Mag in inventory.

My question is there any reason that I cannot install the Slick 4347 mag on the RHS in place of failed mag (Slick 4370)? I have already installed it as the RHS and know it runs on the RHS mag at idle. I have yet to fly it. I have run the mag with both the retard terminal open and grounded, and I could find no difference in operation. In both cases, both ignition sources were off with the switch in the ?Off? position. I am included to tie this terminal to ground.

I would appreciate comments as to the airworthiness of this substitution, and whether the retard terminal should be left open or grounded.

Jerry Ludwig
N925JL

I?d ask Fred Stucklen he?s good with all things electrical IMO. Im sure there?s others who can answer but if you can?t get an answer try and send him a PM super nice guy.

looks like the contacts do nothing if there is no shower of sparks involved. Leave it not connected.

http://www.aircraftmagnetoservice.net/typical-system-with-staring-virbrator

It does not need to be connected. Once the engine starts the "shower of sparks" is off and has no function at all with the operation of the magneto.

Thanks all for the advice. I also found the circuit diagram referred to and concluded that when there is no shower of sparks the retard breaker terminal was a totally open circuit with no function. Since installation i have flown several hours and all is well.

JL