Now tearing my hair out and would really appreciate some advice on this one if anyone can help.
For around 15 years, I had next to no ignition problems with twin points, and later Accuspark electronic unit, then I suddenly had hot starting problems.
Since then I have replaced the rotor arm and cap twice (now running a LD green rotor arm and motor factor sourced Lucas cap, new HT leads, Pertronix Ignitor and have three coils. (A Blue Accuspark, Bosch red and Intermotor), all 6V.
The car starts and runs fine initially, no hot starting issues. The misfire doesn't show until the car is thoroughly warm and has done 10 to 20 miles when the coil is hot. Starts as very slight misfire and gets worse over the next few miles to the point the car misfires under anything but the lightest throttle. Swap the coil for a cold spare and all is good for another 10 miles.
Timing is ok and was set after replacing timing chains, ballast wire checked and 1.5 ohms between fuse 2 and the white/pink coil connection.
There is around 7.1 ohms between coil -ve white/slate tacho coil wire (is this right?) and the 12V supply to the Pertronics is ok.
Earth strap on the distributer plate ok, slight resistance (<0.3 ohms) between distributer plate and battery -ve
When running at tickover, there is only around 2 Volts across the LV coil contacts measured with a DVM and 12V between coil +ve and earth. Is this correct?
Wondering if the Pertronics is faulty, but these devices tend to either work or they don't. I could re-fit the accuspark but it is a bit of a rave.
I don't see why I would need to run a 12V coil without ballast and believe that Pertronix advise against this anyway.
Does anyone have any opinion if my coil is overheating for some reason or if the coil isn't seeing enough voltage across it for some reason causing a weak spark when the coil is hot, or where the fault may be? (it's definitely not fuel related).
Thanks in advance, Mark.
For around 15 years, I had next to no ignition problems with twin points, and later Accuspark electronic unit, then I suddenly had hot starting problems.
Since then I have replaced the rotor arm and cap twice (now running a LD green rotor arm and motor factor sourced Lucas cap, new HT leads, Pertronix Ignitor and have three coils. (A Blue Accuspark, Bosch red and Intermotor), all 6V.
The car starts and runs fine initially, no hot starting issues. The misfire doesn't show until the car is thoroughly warm and has done 10 to 20 miles when the coil is hot. Starts as very slight misfire and gets worse over the next few miles to the point the car misfires under anything but the lightest throttle. Swap the coil for a cold spare and all is good for another 10 miles.
Timing is ok and was set after replacing timing chains, ballast wire checked and 1.5 ohms between fuse 2 and the white/pink coil connection.
There is around 7.1 ohms between coil -ve white/slate tacho coil wire (is this right?) and the 12V supply to the Pertronics is ok.
Earth strap on the distributer plate ok, slight resistance (<0.3 ohms) between distributer plate and battery -ve
When running at tickover, there is only around 2 Volts across the LV coil contacts measured with a DVM and 12V between coil +ve and earth. Is this correct?
Wondering if the Pertronics is faulty, but these devices tend to either work or they don't. I could re-fit the accuspark but it is a bit of a rave.
I don't see why I would need to run a 12V coil without ballast and believe that Pertronix advise against this anyway.
Does anyone have any opinion if my coil is overheating for some reason or if the coil isn't seeing enough voltage across it for some reason causing a weak spark when the coil is hot, or where the fault may be? (it's definitely not fuel related).
Thanks in advance, Mark.
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