Strange Spark Issue

[MKnight702]

I have had problems with the car running badly. Tried to isolate the issue by pulling leads off in turn and seeing if there was any change in rpm. Initially no dice until I held the lead close to the plug and it sparked accross and the revs picked up, push the plug lead on properly and the revs drop again, this was true on both 3 & 4.

Replaced the plugs and leads and it was fine, firing on all cylinders again. Now, a week later, and the car is misfiring again. Is it likely that I have a duff set of Bosch leads or is there something else happening that I don't understand?

I don't believe it is crank sensor bracket as the misfire is at all engine speeds from tickover up to 6k. Plugs show probably running slightly rich, but then I have a Weber 45 so that's probably normal!! (It has been set up on the RR by Peter Baldwin though).

Any ideas?

I'm going to take the new leads back to Halfrauds anyway and get them swapped.

[MillersMule]

What type of coil are you using? Some coils require different wire/lead ends to make a proper connection.

Do you have another coil you can swap?

My guess is a poor connection somewhere, and when you fiddle with the leads or coil pack its fixing itself.

[MKnight702]

It is the type 1 Ford coil pack with the clips on the leads to hold the cable securely. I didn't touch that end when the problems occurred and when I did remove the cables they seemed pretty secure in their sockets. The new cables are all clipped in tight. I can have another go at the coil end but I don't think that that's an issue. In fact the old leads only made good connection when they weren't in contact with the spark plug which is just plain wierd.