Help! It's driving me nuts

[HoggyN]

OK it time to swallow my pride and ask for help.

I can’t get my Series One to run properly. Every so often it loses power and backfires like hell.

Coincidentally (I think) it started just after I fitted a new petrol tank but I initially thought it was a faulty condenser.

Condenser was replaced with a new one - no improvement.

I then suspected that the vents on the new petrol tank were faulty resulting in a vacuum in the tank, which in turn was causing fuel starvation.

I took the cap off – no change

Suspected a faulty fuel pump.

Replaced the pump – no change

Ignition coil was replaced with another, and then another, to be sure.

No change, in fact it was worse, it wouldn’t even start.

Replaced the condenser again.

Started and ran like a dream. Drove it around the farm with no problems for a couple of weeks. Thought it was fixed.

Today took it out on the road for the first time and it ran perfectly. Five miles down the road… Bang! Bang! Ran it for another five with the occasional falter and backfire before stopping to have a look at it. The coil was very hot but the condenser was barely warm. I also noticed smoke coming from the dynamo which stopped when I disconnected it (the wires were not hot). I’m not sure if that is related to the engine running problems or pure coincidence (BTW it was still charging). I eventually got home on the battery but the thing was still banging and farting at intervals despite running as smooth as a sewing machine in between.

For the record it is a bog standard 1955 2 litre Series 1. It runs a dynamo and it is still positive earth. All the ignition components (except the leads) are new and the timing is ok. The wiring loom has been replaced. It will still do 60mph so the engine can't be too bad.

Has anyone any ideas? My wife hates seeing a grown man cry.

[missingsid]

Answers simple.

Bung a V8 in it

Sorry hope some one comes along soon that can help.

Marc.

[Rich_P]

Check the small wire inside the dizzy for shorting out or being broken. If that's damaged or shorting out there will be poor connectivity between the coil and distributor.

I would also suggest that you check the advance and retard, particularly if it's a new distributor that's been fitted. When the engine starts to run poorly, stop it and check the distributor. You may find the central shaft is jammed too far retarded or advanced in relation to the engine speed.

[Les Henson]

I would suggest the dizzy too.

Les.

[HoggyN]

It's fixed!

I thought I'd found the cause this morning when I discovered that the brass contact on the rotor arm was loose. Replaced it and went out for a test drive...

Bang! Bang! Bang!

This time was different, the engine stopped and wouldn't restart. Took the top off the dizzie and checked the contact - perfect. But, and it's a big but, I noticed that the dizzie drive shaft was not engaged. I turned it round until it clicked into place and bingo, the engine would start.

I took the distributor off and found that the cork seal at its base had become dislodged preventing the drive dog from engaging properly. The misfire was caused by it becoming disengaged momentarily. When I backed off the throttle the dog dropped back into place and normal service was resumed as if nothing had happened. No wonder it was a bitch to find. I've replaced the cork seal with an 'O' ring and it's running fine - so far.

Just got to sort the smoking dynamo now.

Thanks for the suggestions