Aldon flame thrower coil and ballast resistor

 
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leloups66
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PostPosted: Wed May 09, 2018 5:49 pm    Post subject: Aldon flame thrower coil and ballast resistor Reply with quote
Hi

My coil died on Saturday - an interesting thing because it tested as if it was sparking but actually the spark wasn't strong enough. Anyway RAC leant me a coil and I got home. Decided to buy a flame thrower coil from Aldon - I thought I did not have a ballast resistor in the circuit. Followed the instructions and it seems like I do have one!. Could find nothing in Haynes manual or anything else so tell me. So I messed up and have bought a 3 ohm one for non ballasted where as I should have a got a 1.5 ohm one. I have electronic ignition. Do I send it back or will it work ok? Any electrical experts out there?
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Alan Drover
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PostPosted: Wed May 09, 2018 6:18 pm    Post subject: Reply with quote
Evening leloups66.
What year of Land Rover have you and which engine? Ballast resistor coils are usually 6 volt. The idea of the resistor is during starting the ballast resistor is bypassed and the coil gets the full 12 volts for starting only. Once the engine has started the key is turned back to the run position and the ballast resistor is back in the circuit. My MGB GT has such a system. It doesn't have anything to do with the impedance of the coil. You should check with the manufacturer of your system what the correct impedance of the coil is. Most electronic systems use the same coil as the old points system and even their uprated coils are 3 ohm. I used a lower impedance coil with the Lumenition system in my Land Rover and first the coil packed up and after I replaced it with one of the correct impedance a misfire developed which was a fault with the ignition module. Fortunately as it was a Lumenition system I wad able to phone them they confirmed that the lower impedance coil had caused the module to start to fail and I was easily able to replace the module.
No Land Rover has a ballast resistor fitted unless it was an aftermarket fitting unlike the MG which has it in the wiring harness (it's actually a length of resistive wire.)Any aftermarket ballast resistor system won't work like the MG set but just supplies a lower voltage to the coil all the time which was a rather pointless exercise.
On the MG the coil is supplied with power via the ignition switch but when the starter motor is activated the coil is supplied with 12 volts via a terminal on the starter motor solenoid (it's a pre engaged motor.)
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Alan Drover.
1975 SWB hardtop with a 2.5 petrol engine, overdrive, front disc brakes, parabolic springs, hand throttle, Defender doors and Wolf wheels.
Also a 1977 Stage 2 MGB GT.


Last edited by Alan Drover on Wed May 09, 2018 6:27 pm; edited 1 time in total
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leloups66
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PostPosted: Wed May 09, 2018 6:26 pm    Post subject: Reply with quote
It is a 1974 2.25 litre petrol.
The manufacturer stated how to check if it has a ballast resistor in the circuit or not. I checked and according to their instructions it does! Electronic ignition so no points to burn out.
A very comprehensive answer Alan but I don't see the answer to my question. Should I use the 3 ohm one or swap it for a 1.5 ohm one. I don't want a misfire like you got.
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Alan Drover
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PostPosted: Thu May 10, 2018 6:59 am    Post subject: Reply with quote
Morning leloups66.
With a standard electronic ignition system a 3 ohm coil is the one to use. The 1.5 ohm ones were used when ignition was changing from coils to ignition packs and were used in the interim period. There was never a ballast resistor fitted to Land Rovers.
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Alan Drover.
1975 SWB hardtop with a 2.5 petrol engine, overdrive, front disc brakes, parabolic springs, hand throttle, Defender doors and Wolf wheels.
Also a 1977 Stage 2 MGB GT.
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Khaki Rover
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PostPosted: Thu May 10, 2018 7:21 am    Post subject: Reply with quote
Hi leloups66,
Out of interest, how did the manufacturer suggest you check if you had a ballast resistor or not?
If it involves checking the voltage into the coil, you might want to check your ignition switch - on my Landy there is a loss of about 1/2 Volt across the switch, but more than that may indicate a problem.
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Alan Drover
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PostPosted: Thu May 10, 2018 8:37 am    Post subject: Reply with quote
Morning again leloups66.
Make sure that the Aldon coil is a 12 volt one and not one designed for use with a ballast resistor otherwise if it is then it won't last very long on a 12 volt supply.
I'd be interested how to check for a ballast resistor as there should be as Khaki Rover said, a 12 volt supply to the coil. The voltage will be substantially less of with a resistor.
Make sure the coil is wired correctly, it's easy to get the connections wrong. Positive is the power supply, negative to the distributor or electronic ignition module if it's not contained in the distributor.
What make of electronic ignition have you fitted?
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Alan Drover.
1975 SWB hardtop with a 2.5 petrol engine, overdrive, front disc brakes, parabolic springs, hand throttle, Defender doors and Wolf wheels.
Also a 1977 Stage 2 MGB GT.
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Geoff2
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PostPosted: Thu May 10, 2018 10:09 am    Post subject: Reply with quote
Quote:
No Land Rover has a ballast resistor fitted unless it was an aftermarket fitting unlike the MG which has it in the wiring harness


Quote:
There was never a ballast resistor fitted to Land Rovers.


I can't help with the OP's question but, just to set the record straight regarding Alan's comments above, both my Stage Ones have a factory-fitted ballast resistor system that works like the MG one described by Alan and, as far as I know, they were standard fitment on all Stage Ones - it's there in the wiring diagram in the Owner's and Workshop Manuals. Sorry, no help to the OP, I know.
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Alan Drover
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PostPosted: Thu May 10, 2018 10:13 am    Post subject: Reply with quote
Thanks Geoff. I don't have any manuals on the Stage 1 but I had forgotten about them in my posting.
The coil will still be 3 ohms impedance.
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Alan Drover.
1975 SWB hardtop with a 2.5 petrol engine, overdrive, front disc brakes, parabolic springs, hand throttle, Defender doors and Wolf wheels.
Also a 1977 Stage 2 MGB GT.
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Geoff2
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PostPosted: Thu May 10, 2018 10:39 am    Post subject: Reply with quote
Forgotten about the Stage One? Shame on you! Smile Seriously, I wonder if it was a V8 thing, as one is also shown in the circuit diagram for the V8 in the 90/110 Workshop Manual but I don't see one there for the four cylinder.
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Alan Drover
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PostPosted: Thu May 10, 2018 11:39 am    Post subject: Reply with quote
Geoff looks like it was specific to the V8. ( Sorry for forgetting about your prides and joys.)
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Alan Drover.
1975 SWB hardtop with a 2.5 petrol engine, overdrive, front disc brakes, parabolic springs, hand throttle, Defender doors and Wolf wheels.
Also a 1977 Stage 2 MGB GT.
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