Re: 1937 ignition coil specs

Posted by HH56 On 2018/5/18 17:29:01

Packard didn't give much info on coils other than amp draw. For 37 coils, the current for "idling" which I assume is points open is 1/2 amp and for "stopped" which is probably points closed is 2 1/2 amps. When testing all they used was a go or no go type coil tester so don't have any actual winding specs but approx half the value of a 12v coil doesn't sound too bad.

Have you verified coil voltage as measured to ground and the possibility of shorts? If pos ground, 6v or battery voltage should be at the negative terminal coming from ign switch. If the points are open 6v would also be on the positive coil terminal or at dist. If points are closed pos terminal should be low near 0v or no more than about 3/10 at the terminals. I would verify the points are closing and the positive or dist terminal is making the change. Also check that nothing in the dist is shorted keeping it at a constant 0 or a high resistance problem with the dist ground is not allowing the points to pull the terminal to a full low. Anything higher than 1/2 v with points closed needs to be looked into. When cranking, ideally the supply voltage to coil should not drop much below 5.5 v. If it goes much lower -- say close to 5v -- the spark will be weak and might not reliably jump the plug gap under compression.