missfire when hot ser2 1969 fhc

[detiid]

Car runs perfectly for approx. 10 t0 15 mins then miss fire develops and then car stops, left to cool it restarts.
I have replaced ignition switch, coil, changed the powerspark ignition system for original distributor, when it stops coil is still live but no spark. I have ordered new leads.
Has any one any clue what to try next?

[mgcjag]

Hi..could well be the coil.(even though u have changed it)...not uncommon for them to go faulty when hot.....you say no spark out of the coil.....is this befor it goes into the dizzy cap..if so sounds like coil.....if spark out of coil ok and no spark at plugs then check dizzy cap/rotor arm....is the carbon contact in the cap in place....it sits on top of rotor arm...hope this helps...Steve

[MSM]

Check the timing and replace the rotor arm with a red one from Distributor Doctor. I had a similar problem and it was coil and timing.

[PeterCrespin]

You have changed things from stock. Your car originally had a ballast resistor and low voltage coil. Mixing coil and resistor specs can cause your symptoms. If you're sure it's a 12V coil try hot wiring it from the battery to see if that helps (remember to disconnect when motor stopped).

[SimonBrown]

I had a very similar problem. Replaced the rotor arm with a red one from the Distributor Doctor.
No further issues