adn both lite aces with the 5k and 4k are listed as GT40R or GT40 RT in the bosch manual. And i have that 5K distributor.

ok so i have spent the better part of half a day physically testing only to come to an abrupt halt.
I attempted to test spark without cranking the engine, but it doesn't work on either of the 2 coils i have, and i suspect this is because the igniter turns off the coil when the engine is below a certain rpm in order to stop it burning out. so cranking is the only way to test, unless u can perhaps jack up the rear and have someone spin the wheels really fast, or perhaps push start the car while someone sits in the engine bay monitoring spark hahaha. Or crank the engine from a different battery.

anyway the results are in and its not good.

FUELMISER CC215
I tested my existing fuelmiser CC215 and it appears to have a nice bright white spark to the unaided eye. I tested it with all circuits normal operating (this includes the electric fuel pump which is on the same circuit as the coil) which takes the volts from 12.4 down to 12 at the coil, but still nice bright white spark. Then tested it again with everythign disconnected apart from the coil, and the spark looked much the same.
THEN
Then i i repeated the test one more time, this time with the coil attached directly to the battery with a new fresh wire, and all other circuits disconnected, and the spark actually appeared to be stronger.
So this teaches us, that the voltage drop from all accessories and in particular electric motors and fuel pumps, greatly affects the power available to the coil while cranking.

BOSCH BLUE
Then i put the old Bosch Blue Coil back in.
With this coil i did the exact same tests again, and interestingly, and, unlike 2 years ago, i could not replicate the bad spark.  :/ It was weaker, but nothing near as bad as it looked 2 years ago before i replaced it.
There was a bit of spark jumping off the insulator to the spark plug body so i cleaned out the plug and tried again and the spark then looked JUST AS GOOD AS THE NEW FUELMISER.



SO at this point i thought for god sake i better just run this old bosch again.
Hooked everything up. 

NO START
The bosch blue is able to make a nice bright spark to the naked eye, but its all a joke, your naked eye cannot test a coil or spark plug.
The spark looks good to the eye, but it lacks the power required to spark a compressed air and fuel mixture. 

I didnt have this issue when i replaced the bosch blue. I replaced it for fuel economy reasons. So i suspect what you said BANJO,  has happened. That is, the coil has burned out the igniter and the igniter is on its last legs, (hence the slight misfiring over the hills), and now combining it with the old 3 ohm coil, there is not enough spark to even stat the engine.

So the fuelmiser is back in for now, and i think I am going to have to look at a new ignition system because the options available with this stock 5K distributor are limited to the GT40R and I am quite sure that sticking a new 1.5 ohm coil on a 1.5 ohm ballast on a burnt igniter will only last a a short while.

Edited December 6, 20178 yr by rebuilder86

Hi Jeremy,  You've missed the point about the extra external resistor. It does not reduce the time to saturate the coil as you state. It is out of circuit (s/c ) whilst starting, so the saturation can be reached. It is in circuit, so the coil only sees 9 volts across it, whilst running at alternator volts, because coils that need a ballast resistor, are designed for 9 volts. Cheers. Banjo

 

oh no i know that. but after start, when its running (through the resistor) surely that will affect the spark size?
I mean, the same 1.5 ohm coil run on ballast will be weaker than without ballast?
But it would be stronger than a 3 ohm coil, because it has the extra 1.5 ohms worth of turns as coil wire making spark rather than 1.5 ohms of resistor reducing current before the coil.

Edited December 6, 20178 yr by rebuilder86

I have a sneakign feeling that the warnign of using 3 ohms doesnt apply to factory igniter systems
Different sources

12V Bosch Blue Coil with Mounting Bracket, US Version, 00-012US is a factory replacement Bosch Blue Coil with the 3 ohm impedance (internal resistance), compatible with points, and points replacement devices, in 12V electrical systems. 

If you are running points, or a points replacement device (Compufire or Pertronix), you MUST make sure your ignition coil has the ballast resistor. Stock Bosch blue coils have the 3 ohm ballast resistor INSIDE the coil. If your coil or primary ignition winding doesn't have this ballast, the distributor will burn up and leave you walking. There are five different "Bosch Blue Coils", and only one of them has the ballast in it.

Edited December 7, 20178 yr by rebuilder86

wow, i found this
Pretty tempted to try the Bosch BIC100 on a 1.5 ohm ballast and just see if it goes well...
Looks as if someone has gone and tested the power of all the coils available.

ok this needs to be settled. and ahoukd be settled here.

the rexommendation by hot spark and the likes, do not apply to original equipment. the minimum specs of 3 ohms is for their dodgy aftermarket creation only.

see this screenshot of a bosch document.

Note

it sais HEC/MEC coils are for electronic distributors.

HEC and MEC coils go down to o.5 ohms.

This proves tgat the recommendation for 3 ohms only applies to aftermarket points replacement devices. 

The confusion would have come directly from thibgs like this .an EK kit is another electronic conversion. conversion kits are the problem.

Bosch EK kits must not be used with HEC or MEC ignition coils

It is recommended that ignition coils designed for use with contact sets are not used with any electronic ignition module, as higher than normal back voltage may damage the switching transistor. Bosch EK kits are designed to operate with SU120R and GT40R ignition coils, along with the original ballast resistor. Only the original vehicle coil can be used, otherwise the switching transistor will be destroyed.

my current coil is fine, and my missfire must by a dodgy electric fuel pump.(again)

thats the difference between research and blindly beleiving everything.

 

Dammit!  Went & bought the Fuelmiser CC215 based on its 0.6ohm primary, but sitting on my desk here it has a resistance of 1.3ohm, the same as any points coil! I'll check with the guys on Ebay and see what else they have.