mis fire

[EuropatcSPECIAL]

Evening all, I had a misfire on number two (tc Special) I changed the cap, rota arm, leads problem cured it was the cap that was cracked. I went to start it yesterday and its on 3 again. At first I thought it could be flooded as I had not started the car for 6 weeks.  Again number two flooded. dried the plugs still missing. I took the distributor cap off and there are so tiny flecks of brass inside the cap. The terminals in the cap look ok as does the rota arm. All the new equipment has done less than 1000 miles. I'm thinking perhaps the distributor? Anyone had any similar experience please
thanking you in anticipation
all the best
Stuart

[BDA]

Is there any slop in the distributor?

[EuropatcSPECIAL]

Hi BDA just a tad

[BDA]

I wasn't clear, but I was referring to radial slop, not rotational slop (there should be a little of that from the gears that drive it). If the shaft wobbles in the body of the distributor, I wonder if this could be the problem: the slop in the distributor shaft doesn't allow the spark to get from the rotor to the cap electrodes reliably as well as some interference between the rotor and cap is causing the flaking. I'm thinking the fact that you're having trouble with #2 and #3 (did I understand that correctly?) might also be evidence of that. Otherwise, I would think the same cylinder would misfire - in which case I would change that plug and try again. The thing that makes me wonder is that I would expect that you'd see evidence of arcing from the rotor to the cap.

I have to say, the only problem I've had with a distributor is when the one on my Ford Probe went out and left me stranded, so I don't have a lot of experience to draw from. I guess I've been lucky. It might be time to find a shop with an old distributor machine (if there are any more) and have it tested or inspected to possibly rebuild it.

A couple of things come to mind when thinking about this. First, if you don't have one all ready, I would advise getting and installing a Pertronix ignition while the distributor is out. Second, you do know that you folks who have Twin Cams actually have Triplet Cams?   

[Arizona]

A couple of things come to mind when thinking about this. First, if you don't have one all ready, I would advise getting and installing a Pertronix ignition while the distributor is out.

That would be my suggestion also, and now you can even get a Pertronix distributor to replace the Lucas.
http://www.pertronix.com/prod/ig/flame/dist/british.aspx

[Bainford]

I had a miss on my Twin Cam which turned out to be the plug wire. It was laying against the sharp edge of the cam cover and wore through a bit until the spark was able to arc through the wire casing to ground. Took me awhile to find it. Its worth a look.

[EuropaTC]

I took the distributor cap off and there are so tiny flecks of brass inside the cap. The terminals in the cap look ok as does the rota arm. All the new equipment has done less than 1000 miles.

hmmm, I wonder where the brass is coming from ?  The most obvious source is the rotor arm, or if the replacement cap has brass terminals, I'm struggling to think of other places it could come from but we both know that it shouldn't be there.

At this stage my first thoughts would be that the spark is tracking internally over the brass dust inside and I'm a little surprised it's not a random misfire.  As you're in the UK I'm sure you've seen reports of dodgy rotor arms and cheap ignition parts on the market so I'd be looking very closely at the fit and appearances, maybe a 10x magnifying glass ?

Finally, I'm another Pertronix guy & I've got them on both Elan & Europa. For a luddite like me it was a traumatic move into the 21st century but one worth making. 

[EuropatcSPECIAL]

Gents onwards and up wards, Im off down to the garage now to have a strip down. Thank you for the great response (as always) watch this space
all the best
Stuart

[EuropaTC]

Second, you do know that you folks who have Twin Cams actually have Triplet Cams?   

Yes, but this is Lotus - it's always as well to have an installed spare.......   

[4129R]

Although the third shaft used to be the camshaft for pushrod  engines, for twin cams, it only uses an eccentric circle for the fuel pump and a gear drive for the distributor, so it is not really the third camshaft.

I was stripping down one of my engines over the weekend, so I am up close and personal to all the inner engine bits.

This particular engine had 4 rusty pistons that had to be carefully hammered out of the bores. The block is off for a re-bore then I have to carefully stick everything back together with much black goo to stop future oil leaks.

[BDA]

Although the third shaft used to be the camshaft for pushrod  engines, for twin cams, it only uses an eccentric circle for the fuel pump and a gear drive for the distributor, so it is not really the third camshaft.

I know! It was a tongue in cheek comment! That's why the   

I could draw a comparison to my BDA which does not have that third camshaft but rather a jack shaft that only drives the distributor (I don't think it has an eccentric to drive a mechanical fuel pump, but I could be wrong). So my BDA is a TRUE twin cam! 

[EuropatcSPECIAL]

Gents joyous news. In the cold light of day , when stripped down again the problem was found. The rota arm. Where it pushes on to the shaft there was one tiny piece of hard plastic which would not allow the rota to sit down square. A little bit of fettling and we are on all four again
cheers chaps
all the best
Stuart

[BDA]

Great news!!! Congratulations on finding the problem!!! 

[jbcollier]

"I have to carefully stick everything back together with much black goo to stop future oil leaks."

Careful with the excessive use of sealers.  I have seen engines where chunks of excess silicone have broken free and plugged oil passages.

[BDA]

That reminds me of what an engine builder told me happened to a race car they built: at some point, they couldn't get it to fire at all. After they looked at everything, they finally opened up the fuel system. They had apparently used a lot of silicone seal on their fuel cell. Even though fuel is not supposed to attack it, it had softened it up and it ended up being a rope of silicone in the fuel line from the cell toward the pump blocking the hose. The moral of the story is don't use too much sealant of any kind on anything. It could come around and bite you!