260z or 280z Distributor into 240z

[Harry Dinkle]

I don't know about the 280zx coil, but 280z had a 0.45-0.65ohm coil with a 1.15-1.45 ohm ballast resistor for 1.8 ohm total.  The 240z (points distributors) had a 1.5 ohm coil and 1.5 ohm ballast for 3 ohm total.

I am not going the 280zx route but the tach wiring is the same as Blue's instructions so I should be good.

[Zed Head]

25 minutes ago, Harry Dinkle said:

I believe you don't need any ballast with the HEI module because as you have stated, it limits the current so there is no need for a current limiting resistor.  The Pertronix D2000 Flamethrower module limits current to 6.9A.  The 280z stock setup should be 6.6A (12v/1.8ohm) so it isn't a huge upgrade which is why keeping the stock ballast/coil setup in a 280z could be just fine.

My current planned setup is 260z distributor, Pertronix D2000 HEI module, Flamethrower II coil 0.6ohm, no ballast resistor.  Jump the two wires currently on the ballast so my tach still works.

I think that the low resistance primary circuit allows a faster "ramp up" to saturation for the coil current.  It's not just the voltage-primary resistance calculation that matters.  You need a fast ramp time at higher RPM because the time available to reach saturation is shorter.  The Pertronix 6.9 A limit will produce more heat and will degrade your parts faster.  If you don't have a turbo or are running at 7500+ RPM it's kind of an unnecessary heat load on the system.  I use the actual GM HEI coil with my GM HEI module, just for parts harmony.  The GM HEI coil has about 0.4 - 0.6 ohm primary resistance.  By the way, with a good alternator you'll see over 14 volts.

Also, the reason for connecting the two wires at the ballast is because one is Start power and the other is Run power.  With the ballast in-use they bypassed the ballast to balance the voltage drop from the starter draw.

Here's an interesting file I found out there about coils.  I was looking for ramp rate and it's in there but there's a bunch of other neat stuff too.

http://www.beruparts.co.uk/content/dam/marketing/emea/beru/brochure/en-all-about-ignition-coils.pdf

[EuroDat]

When I changed over to the HEI module I bridged the ballast resistor and fitted the HEI module into the old TIU case to keep it as original looking as possible.

 

Edited July 31, 2018 by EuroDat