Missing elan plus 2

[tdafforn]

Before I rebuilt my engine it used to missfire at idle..
Watching the engine one night at idle and noticed periodically a nice fat spark would jump from the engine block by the thermostat to the brake servo!
the before my very eyes it jumped to the temp sender wire and the wire began to melt!
anyhow cleaned the engine earthing points and it all went away..
Now I run wasted spark, with no problems
Tim

[gwiz22]

Stonks,

I had a similar problem. I wasn't so much a misfire, the engine just wouldn't run smooth. It seemd to be running on three cylinders. I tried all the suggestions you have had so far and then some. For me, it turned out that the plugs were fouling. I'd take them out and 3 of them were sooty black and one was wet. On a new set of plugs, it would run ok for a bit, then one would become wet. This was a random process, not always the same cylinder. After a few iterations of this, in desperation for another set of plugs after Halfords was shut, I went over to my son's old Fiesta XR2, took out his old N9Ys which had done thousands of miles, put them in the twin cam and the engine burst into full reving action on all four cylinders. I adjusted the carbs for mixture and tickover and never had the problem since. So if you are running N7Ys try replacing them with N9Ys.

BTW, my plugs are still always black which signifies rich running. However, when I weaken the mixture the tickover goes rough. If anybody knows how to get a twin cam to provide smooth running and the plugs a nice mid brown colour, I'd love to here from them.

Good luck

Graham.

[paddy]

BTW, my plugs are still always black which signifies rich running. However, when I weaken the mixture the tickover goes rough. If anybody knows how to get a twin cam to provide smooth running and the plugs a nice mid brown colour, I'd love to here from them.

The mixture adjustment screw only affects the mixture at idle. The mixture when running is primarily determined by the all the various permutations of jet sizes together with air filtering arrangements, float level etc. It sounds like you may need to check everything is to spec there. I had a problem with rich running which turned out to be because the carbs had an odd collection of different jets in, all wrong.

Paddy

[gwiz22]

Paddy,

Thanks for your feedback. I have checked all the jets etc. and they are as per the manual. I'm reluctant to go experimenting. I am hoping someone has had the same issues and found a set of jets that gives mid brown plugs and smooth running with no hiccups through the rev range.

Alternatively, one day I'll take it to a rolling road. Again, I would really like to know of a company with good experience of the twin cam.

Regards
Graham

[paddy]

Alternatively, one day I'll take it to a rolling road. Again, I would really like to know of a company with good experience of the twin cam.

Ian at GRL motors in Woking has a rolling road, lots of twink experience, knows his Webers inside out, and has a complete stock of all of the different jets. Very highly recommended from my own experience.

http://www.grlmotors.co.uk/

Don't email (he never replies), but call the number on the website.

Paddy

[stonks]

Well, so far I have replaced the plugs - again with NGK ones, replaced the points and coil with a contact less set, see ebay item 120486932971. for twenty odd pounds it just rules out any issues. fits with very minor mod to baseplate.

Will replace the leads again. I will advise you once I get the time to spend more time on it....

[gwiz22]

Stonks,

I visited GRL motors mentioned by Paddy earlier in this thread to get an idea of how much a rolling road session would cost. I spoke with Ian, again mentioned by Paddy, and he was very helpful an seemed very knowledgeable on the twin cam engine. One thing he mentioned as a typical issue with old twin cams is the distributor. He commented that after 30 odd years, you have to expect some wear in the shaft and the weights and springs in the advance mechanism get tired and worn. He generally replaces them with an electronic version. It is still a distributor as we know it, it looks the same and works in conjunction with the electronic ignition, it just has an electronic module where the weights and springs normally reside. This can be accurately set for the required ignition advance as the engine moves up the rev range.

As you initially suspected the distributor in your first post, and as you have changed everything else, I thought this info may be of interest.

BTW, GRL Motors charge ?70 per hour (plus VAT I guess) for rolling road services. Ian said he can typically sort a twin cam out in 1 to 3 hours depending on what needs doing. He said, you will always get an improvement in power output after a RR session, how much depends on how poor it was to start with. I have a few things to do to my Plus 2 over the winter and plan to invest in their services in the spring.

Regards
Graham

[tawnyowl]

Copied from an earlier post. Many cars must have this problem.

I had a similar problem once which took months to resolve as it was so deceptively obscure. The symptoms were the same, everything Ok until you want some power then it dies.

The problem was fuel starvation and was caused by flakes of rust from the inside of the fuel tank coagulating in the bottom of the fuel tank and partially blocking the outlet pipe.

To check/clear syphon the petrol from the tank and then undo the banjo thingy below the tank and clear all the stuff out.

Tawny