0-320-D2J converting to single impulse coupling ignition

New guy introduction
I am Carl Bray, retired, airplane nut, residing @TA66, Pipe Creek, Texas
'56 Cessna 172
'85 Wittman Tailwind W8/W10
advise needed
0-320-D2J lists dual impulses coupled slick 4371 magnetos (25 degree lag)
for experimental application, what are the cons of installing slick 4370 on the right side and slick 4373 (impulsed coupled, 20 degree lag) on the left.
the reason I am asking, the engine log has no endorsement of any magneto inspection or replacement
engine logs shows 1800 TT, first run.
I have the slick 4370 and 4373, purchased for another project

regards
carl

Quote:

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Originally Posted by Carl Bray

New guy introduction
I am Carl Bray, retired, airplane nut, residing @TA66, Pipe Creek, Texas
'56 Cessna 172
'85 Wittman Tailwind W8/W10
advise needed
0-320-D2J lists dual impulses coupled slick 4371 magnetos (25 degree lag)
for experimental application, what are the cons of installing slick 4370 on the right side and slick 4373 (impulsed coupled, 20 degree lag) on the left.
the reason I am asking, the engine log has no endorsement of any magneto inspection or replacement
engine logs shows 1800 TT, first run.
I have the slick 4370 and 4373, purchased for another project
l

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I don't see a problem jumping out right off. Stock electric starter?

Not being logged doesn't mean nothing ever happened.

Quote:

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Originally Posted by Carl Bray

....slick 4371 magnetos (25 degree lag) ....slick 4373 (impulsed coupled, 20 degree lag)...

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OK,
I'm stupid enough to stick my keyboard out. If the impulse couplings have different lags, will that affect starting?

Mike M. That is a valid point.

Less lag on the impulse coupling could potentially allow the engine to kick back while cranking. I have tested that configuration with acceptable results

The last time my impulse coupled mag croaked on my O-320-E2G (Experimental SuperCub), I replaced it with a relatively new mag I had sitting on the shelf that had 20° lag rather than spending the $$ to buy a new mag with a 25° lag as called out in the engine manual. That was 250 hrs ago, and I have not experienced any issues with kickback or any adverse issues with starting. My O-320-E2G is the same core wide deck O-320 engine as the D2J model in the original post. As always, apply the standard disclaimer... "your mileage may vary."

-Cub Builder

A 320 isn't a hard staring engine and most of them had only one impulse mag. You'll need to put shorter studs in the accessory case on the right. Regardless of people trying it and getting lucky, the risk of kickback is still there. Imagine some poor bastard hand propping it when that happens. It's the wrong mag for the engine. Period. Think of the next person that might own your plane when you decide to install potentially hazardous parts.

The other issue you might have is your ignition switch. It needs to ground the right mag during start. If you have toggle switches, you're ok. Bendix style key switch, maybe not.

If one of the 4371 couplings is in good shape, swap it to the 4373. You could even use the new spring from the 4373.

I agree the issue is not starting using the starter. The issue rises when someone needs to or attempts to hand prop it. But saying this, could you not start on one mag, then once running switch both mags on? My A-65 only had an impulse on one mag. You started on one mag then switched them both on when running. Just placard the panel with these instruction and put it in the check list. Do Not Start on both Mags. Seems simple enough, if one looks at placards and checklists that is.

Tony

I thank all that replied, it helped my make a decision

regards
carl