Identifing Ingntion coil

[5bzhive]

I hope this is in the correct forum for this but it seems I have a coil dilemma.

A PO for my 4/73 240 put in an L28 with electronic ignition but left the coil's ballast resistor in place and hooked up.

Now I am trying to determine if I have the 240 coil and should leave the resistor hooked up or do I have a 280 coil and can remove the resistor.

The car seems to run fine but as always I want to get the most bang for my buck.

I have measured the resistance of the primary and secondary windings and find that, except for the a low reading on the primary for a 240 and a little high for a 280 (mine is 1.1ohms on the primary while the 240 FSM says 1.5-1.7 ohms and the 280 FSM says 0.84-1.02ohms), my secondary resistance fits into either the 240 or 280 ranges. Now this begs the question why can't a 240 coil handle the full voltage like a newer 280 coil? I mean that if the Resistance is within specs for both types then is there some type of difference in the material/construction that makes the 240 coil heat up more and fry?

I have checked the input voltage with and without the resistor and found that without it the coil is only getting about one more volt (13.3 instead of 12.25). I find that funny too because across the battery I have a little over 14 volts while at idle.

My tuning ear tells me that there is not a noticeable difference in the engine at idle with or without the resistor, but i haven't driven it with the resistor bypassed yet.

Any thoughts on how to ID the coils? there is no sticker or numbers on the coil and as far as i can tell it looks just like any other oil filled coil I have seen.

Glen

[240260280z]

- 1.1V is much closer to the 280z coil's specs.

- when taking a resistance measurement using a voltmeter, first touch the two leads together. The reading should be 0.00 ohms.If it reads 0.XX then the XX is the resistance of your leads and you should subtract that from your measurement of the coil.

Real World Advice:

The ballast resistor (current limiting resistor) is to prevent too much current flow from burning up your points (on an old distributor) or from burning up the switching transistors on an electronic distributor or from overheating your coil primary.

The 280zx distributor (with the transistors in a little black package on the side of the distributor can easily operate w/o the ballast resistor. You can also buy $30 coils that can operate w/o the ballast resistor if your's fails.

For better reliability, ensure your ignition module (electronics) has adequate cooling AND also that your coil has adequate cooling.

[5bzhive]

Blue

I did check the leads for resistance and it was 0.00.

I just was trying to figure out which way to go with this thing.

Thanks for your time in making a reply.

Glen