What is the best ignition coil to use in a 73 squareback?

Thanks
Beetle Bailey

Bosch

There use to be the Blue coil

Most of the ones i have seen are Black

pretty sure the model is a SU12 ???

I did hear the blue was suitable for points and the Black was suitable for points and electronic

Whatever coil you use it has to be one with an internal resistor.

Internal resistor?????? No such animal dude.

nah, you either use an external ballast resistor and a cranking bypass wire for a 12V system or you use a plain 12V coil without a resistor at all.
The a 12V coil that requires a ballast resistor is really a...probably say a 8 or 9 volt coil and the ballast resistor drops the voltage to the coil to 9V when running.
The bypass wire bypasses the resistor on cranking to supply full battery voltage (whatever that may be depending on how good the battery is!) to the coil to assist in a stronger spark for easier starting, particularly when in cold and/or wet conditions.

Running a ballasted coil without a ballast resistor results in a very strong spark but leads to coil overheating and premature failure and points burning due to overly high currents being switched.

The electronic coils are designed to operate with extremely long dwell (coil switched on) times.
Most EFI cars ECU's simply pull the coil on and momentarily cut the negative side of the coil to induce spark whereas ye olde fashionede Kettering (points/ciol) system holds the coil on for a majorly reduced dwell time. Usually around 40 to 50 degrees (hence the term Dwell Angle)

So, an electronic coil running on a points ignition system tends to produce a weak spark unless the points gap is reduced to just a few thou to obtain absolutely maximum dwell time and then you have the drama of points arcing and spark timing scatter to deal with and a points type of coil running on an electronic ignition system tends to overheat and are prone to failure.

there you have it dudes

l8tr
E

The Bosch GT40 is probably the best oil filled coil for the VWs.
It has a higher spark output than a standard coil..
I have always used them, but I have just had to go to a standard coil to use with a high energy electronic ignition.
I wouldn't recommend the Non oil filled coils either...
So long as it isn't a resistor type...

Lee

I gotta ask why the problem with transformer type ignition coils?
If they are good enough for near enough every car and bike manufacturer in the world for the last god knows how many years then why not for a bloody dak dak kraut.
Have there been a raft of failures of them?
My two, and just about every other race car and motorcycle I know of use them with good results so why the resistance (no pun) to them and the insistance to cling to what amounts to dinosaur technology???

I gots 2 know.

l8tr
E

Original point made.

I have just heard the non oil filled coils fail with the high temperatures in a VW engine bay...
Who runs them in VW engine Bay???
I know everything else uses them these days....
Maybe its time for a change.....
they do look better than the prehistoric oil filled coils....
Although You can't get chromed ones

Lee

I still fail to see where the failure issue lies with these coils.

I cannot see why the engine bay of a dak dak would be any hotter than any other given that the engine bays of nearly all front engined cars have a radiator blasting hot air in there and massive amounts of radiated heat from exposed zorst manifolds, where most of the hot air from a kraut is ducted under and out along with the zorst.

Furthermore, what about the many cars that utillise a seperate coil attached directly to the spark plug in the very extreme and breathless conditions nestled between the cam covers of twin cam engines, subject to extreme heat and vibration and they seem to last just fine.

I tend to think that a lot of the responses here against the use of transformer coils is a result of innuendo and heresay and not necessarily based on fact.

There hasnt been an oil filled coil used in the most extreme of environments as the underside of a motorcycle fuel tank in dozens of years!

I am willing to bet that no-one can document any higher percentage of transformer coil failures than oil filled coil failures.

However, no they are not available in chrome but i reckon there is a market there for chrome covers for them!!!!! L8tr
E

OK....
I agree...
My Lancer has them sitting on the tappet cover.... and it does get very hot under there....
I don't know what voltage they give out.
The high energy electronic ignition I am installing says NOT to use a GT 40 Bosch coil as the voltage will be too high and they will burn out.... A standard coil must be used...
I think it puts around 100v into the coil....
cheers

Lee

Sounds like you are fitting some type of CDI system yeah?
Is the coil powered directly from the ignition itself?
This would explain the call for a standard coil.
However, a GT40 (not GT40R) coil for use without a ballast resistor can be considered a standard coil and will cope perfectly weell with 100V dump voltages.

I have a couple of old CDI's here, (the ones that whistle incessantly), that we have modified in the past to dump around 500V into the front end of the coil and GT40's worked just fine with them.

The sight of the dizzy cap and plug leads on a damp night is quite amusing with St Elmos fire dancing everywhere and the plug electrodes would erode down into the insulator tip after about 8000 K's!

We had to gap them neartly every couple of weeks!!!!

Fit your electronic system with your non-ballasted GT40 and go and enjoy it bloke.

L8tr
E

Interesting reading, Tass. Reminds me of a Fiat 500 I once owned. Quite a standard engine, nothing souped up at all. Despite replacing HT leads, etc, etc, I could never stop it sparking like you mention. BTW, St. Elmo's fire is usually associated with aircraft in conditions of electrical storms, no? So what patron saint do we use? St. Kettering? St. Agnelli? :-) Cheers.

Check this out. It's the Bosch ignition coil application guide.

http://www.bosch.com.au/productcatalogue/sat/products/files/ignition_coils.pdf

There are a few aircooled beetles listed that can take the new transformer type coils (GT40T). But why don't they have kombis (type 2) listed?

Dont worry too much about those bosch cattledogs dude. My wifes Pulsar Turbo needed a coil recently and Bosch had no listing for that despite having a listing for the atmo pulsar.

Paul. bwaaahahahahahahahahah! St Ketterings fire.........LMAO
Your right, but I got a sneaking suspicion that St Elmos fire goes way further back to old sailing ships where the rigging would sometimes light up in the appropriate weather conditions.


St Ketterings fire.................LOLOLOLOL