1956 Johnson FD-10 coil test

[YN2(SS)]

i have a intemittent miss at idle and im believe it is an ignition problem. I have new coils but rather than jus replace the coils, is there any way to test them?

 

[kbait]

Re: 1956 Johnson FD-10 coil test

If the current coils aren't cracked, and you have an intermittent miss, I'd try filing up the pointset faces to shiny and re-setting to .020" and give it a go.. w/new spark plugs j6c champions gapped to .030".

 

[freddyray21]

Re: 1956 Johnson FD-10 coil test

as stated if the coils are not cracked then they are rarely bad. I would check points. clean and regap and also replace condensers

 

[kfa4303]

Re: 1956 Johnson FD-10 coil test

I agree if the coils aren't damaged, scorched, or cracked they're probably ok, and cleaning and resetting the points is always good, but new s'plug wires may be in order too. They can wiggle loose from the coils' posts and/or corrode over time. New 7mm copper core (or stainless steel) wires will make a world of difference. They usually sell it for about $3 a foot at places like NAPA or Carquest. Spark should be able to jump 1/4" gap once evrything is working properly again.

 

[YN2(SS)]

Re: 1956 Johnson FD-10 coil test

Well, I ran the motor yeaterday and found by using a timing light that my miss is only on the lower cylinder. I swapped plugs and found the miss remained on the lower cylinder. I have already purchased NGK plugs, 2 coils and a points and condensor set from here. When I removed the flywheel, I found on coil looks fairly new and the same as my new ones. The other however has some black soot on it and the coil itself is loose on it's mount. I noticed a thin black line of residue where the coil attaches to it's mount. So I'm gonna assume the coil is bad. I'm gonna totally disassemble and inspect the whole area, replace that coil, the points and condensers, replace the high tension leads and plugs. Adjust the coils and gap the plugs and points, out her together and set the sync. That's shud do it. Shuoud I do anythin else?

 

[kfa4303]

Re: 1956 Johnson FD-10 coil test

That should do it, but get Champion J4C plugs, rather than the NGK variety. Overall, it's a surprisingly easy job to rebuild the magneto system. Do one half at a time, if you're unsure, that way you have a guide and be sure to twist the new s'plug wires on to the coil post. Here's a handy pic. Keep us posted. Good luck.