[Freddie]

My 75 Spider just got some new NGK plugs and a new electronic ignition. Carbi's checked and found to be Ok not requiiring any work.

I still find it hard to start and when it does start, it runs really rough. The leads have not been changed yet and I'm not sure how old they are. But what I've found is that it seems as if it's running on 3 cylinders, coughing and splattering for at least 5 mins.

However, after that, it runs quit smooth. It does seem to be running rich with a substantial petrol smell from the exhaust.

Should I look at replacing the leads, and if so, which brand should I look at.
Being a 1975 model, do I need to change the type of fuel I use. Are trhere any other things that I need to looks at?.

 

[eedneco]

If you think it's running on 3 cylinders, you can locate which one is not firing quite easily - by checking the temperature of each exhaust branch.
e.g. from cold, start it, and keep feeling each exhaust branch with a bare hand, you'll soon tell which ones are heating up and which one isn't. Or if already hot, squirt a bit of water, or spit, onto each exhaust branch and compare the fizzing off, you'll see which it is.

Take the plug out of that cylinder and change it (or swap with another cylinder's plug) and see if the problem follows the plug. It is possible to get a faulty plug.

During the time the plug isn't firing, you'll be accumulating unburnt fuel in that cylinder. A lot and it'll end up in your sump too.

Clearly, if the problem doesn't follow the plug, moving the plug wire is the next thing. Obviously make sure your lead contacts are making good contact at both ends, and that boots haven't gotten pulled outward, keeping the contact from being solid.

Hope that helps a bit.
Neil

 

[Freddie]

Thanks for the advice. OK, I'll adopt this theory and see if I can isolate the problem.

But also, it seems that after say, 5 mins, the car runs smoothly after it has warmed up. Many years ago I had an Alfetta GTV and back then discovered that a cracked lead gave me similar symptons as did a faulty plug.

As I said i don't know how old the leads were when I got the car and it has been sitting for about 7 years. If I were to also change the leads, is there a particular brand In should stick to.

 

[Dennie Cliff]

Hi Freddie, I had the same symptoms per my 74 spider. It ran on two or three cylinders upon starting and later smoothed out and ran fine. In my engine it was extremely easy to foul the plugs if I wasn't estremely careful when starting the engine. I struggled for a long time trying to lean out rich running Webers and finally replaced the old Webers with new ones and installed a MSD capacitive discharge ignition. Gas on a plug will foul it and cause it not to fire. Pulling a plug and looking at it may not tell you if it is fouled. If I suspect a fouled plug I heat the plug threads with a torch being careful not to heat the ceramic insulator. The heat rids the plug of gas fouling. What did your old plugs look like? If your carbs are running rich then you will have black soot on your plugs. Good luck, Dennie