Bendix Mags, add impulse coupling?

[Mike S]

I have the Bendix SF4RN-8 mags on the A65-8 and they're due for overhaul. Is it possible to add an impulse coupling to one of them?

[Ragwing nut]

Re: Bendix Mags, add impulse coupling?

Not sure they ever had an impulse for them, hence the reason you saw one eismann and one bendix

[Edwin Otha]

Re: Bendix Mags, add impulse coupling?

Seen some with impulse but never on an A65. Those little mags are hotter than a three peckerd goat. Very hot spark at low speed, you shouldn't need them.
EO

[Nefj40]

Re: Bendix Mags, add impulse coupling?

I've got a A65/75 with dual Bendix and one does have a impulse coupling. I don't know if there's different -8 acc. cases, but on mine there's only room for a ic on one side. It's always been incredibly easy to start.

[Mike S]

Re: Bendix Mags, add impulse coupling?

on mine there's only room for a ic on one side

Clearance does look a little tight behind them. I've got a call into the rebuilder but no joy as it was after Miller time Friday afternoon, so it'll have to wait until next week.

[3Dreaming]

Re: Bendix Mags, add impulse coupling?

With a good coil, condenser, and freshly magnetized rotors these mags will work better than a impulse coupled mag. You just can't be lazy when starting the engine. It takes a nice quick flip of the prop.

[Nefj40]

Re: Bendix Mags, add impulse coupling?

Clearance does look a little tight behind them. I've got a call into the rebuilder but no joy as it was after Miller time Friday afternoon, so it'll have to wait until next week.

I should have clarified better. I was talking about clearances inside the acc. case. I can't take the mag with the IC and put it on the other side, it hits internally on the back of the crank case. I guess to make it easier to understand, one mag has a longer shaft for the IC and something internally was done to compensate for that. I know this because I chased my tail for months thinking I had a ignition problem and tried to swap mags side to side. I'd have to check, but I think the IC mag was on the right.

[Guest]

Re: Bendix Mags, add impulse coupling?

I have at least two brand new never used coils for those mags if you are interested pm me.

Dave R

[Kerbs]

Re: Bendix Mags, add impulse coupling?

I have dual bendix mags with an impulse coupler on the left mag only. Happy to take a picture if its of any help.

[Garry Crookham]

Re: Bendix Mags, add impulse coupling?

SF4RN-8 mags were non-impulse mags. S4RN-20 mags were non-impulse and S4RN-21 mags had an impulse. Both types of mags are approved on the A65-8 engines. Early accessory cases were made to accept impulse mags on the left side only. Late style accessory cases were made to handle impulse mags on both sides.

[Garry Crookham]

Re: Bendix Mags, add impulse coupling?

Continental SB M47-16

[Edwin Otha]

Re: Bendix Mags, add impulse coupling?

Looks like the SF4 on the 65 never had an impulse installed. Shouldn't ever need one the spark is real hot in these little mags.
Any retard magneto should be installed on the left side only if you are using a single impulse or retard breaker magneto.
The SF4 magnetos are the little lunch box mags and the S4RN are the standard cased mag we use now days.
EO

[Garry Crookham]

Re: Bendix Mags, add impulse coupling?

Picture of 4 mags approved on an A-65: left to right Case 47, Eiseman AM-4, Bendix S4RN-21, Bendix SF4RN-8

[Mike S]

Re: Bendix Mags, add impulse coupling?

Thanks for the replies and info.