8n coil

[profire31]

Can anyone please tell me if the is a way to test a coil to see if it is good? I'm dealing with a 1949 8n that is still on a 6V system. thanks.

 

[souNdguy]

Yeah..

pull a spark plug wire and stick a spare plug in it and ground the threads to the head and crank over... if ya got blue spark you are good. if not.. make sure you have power to the coil and that points open and close electrically.

technically you can check continuity ont he primary and secondary.. about 1 ohm on the primary screwtop to the pigtail, and about 4k or so from the screw top to the flat spring... that's a basic test.. might still have shorted turns even if it has continuity...

open condition however will be tell-tale..e tc.

post back if you need more help.

soundguy

 

[profire31]

Thanks for the quick response. I don't have a ohm meter so I'm gonna skip that part but I did do this. I got power to the coil and through to the points. When I crank it over there is no fire coming to the plugs. Can say this. I took the dist. cap off and checked where the little spring thing on the coil was sitting. It had somehow gotten put on wrong and it was touching the screw (like it's supposed to) but also the distrubitor. After I had stopped cranking on it about a minute later I heard a little pop from the front of the tractor. Not real sure where it came from but I did notice the coil was warm to the touch. I'm thinking I fried $35. Thanks again. Probally would have helped to said all this the first time. Sorry for not it's only my lack of experience coming out. Cliff

 

[souNdguy]

A test lamp inline to ground with the coil will tell you about the primary.. not real easy to test the secondary without some equipment though... even a volt meter.. etc.

coils can pop and crack their epoxy / plastic / metal housings.. sometimes this is the end of them.. sometimes it's just a lil too much thermal expansion.

basically you need power to the top terminal.. down theru the primary winding, to the points screw, thru the points and to ground... ( points must oepn and close ).. condensor acts as a switch debouncer across the points gap to keep them from burning. secondary should make KV when the points open for the distrib cap and rotor to 'distribute' tot he plug wires and plugs.

pull a plug and check spark.

soundguy

 

[profire31]

thanks for the info. I still have power coming through the coil as I did test it down through through the points. I did pull and check for spark in all 4 plugs. Nothing there. Guessing it's something with the points opening and closing as I'm thinking they aren't doing the closing part.

 

[souNdguy]

can trick em on the bench with some gator clips and battery cables since the distrib comes off with 2 bolts..

soundguy

 

[profire31]

cool. I'll try some other stuff in the morning. I'm thinking it has to be something simple. Thanks for your help.

 

[souNdguy]

start a new thread when you post back to bring us up to speed.

soundguy

 

[profire31]

will do. thanks again