How hot should a coil get? Lotus breaks down - press shocker

[TimHaydnJones]

I am in the process of bringing Linford Lotus
http://www.facebook.com/album.php?aid=269116&i...
back to life after too long under a sheet.
He's just had a cam-belt change, plus various other obvious bits and bobs so I thought I'd take him for a short run, just to get him up to operating temperature for the first time in years and have a bit of air run through him.
He dumped me at the side of the road! Bless!
Boyish enthusiasm on my part, I know, as good old Linford did have a knack of dumping me at the side of the road - why do you think he was garaged in the first place?
Anyway - to get to the point - my theory is that something is making the Lumenition Optronic electronic ignition throw his hand in - let it all cool down and he used to restart and take you home.
At the point he stopped today, the Lumenition box of tricks was cool. The coil wasn't red hot but it was somewhere between very warm and hot. Is this expected?
I've read various threads that the Lumenition Optronic doesn't like a dodgy earth (and Lotus's are famous for dodgy earths) but I'd had the Lumentition earth wired straight back to the battery.

So, back to the question - how hot should a coil get? - could I have fried it?
and does anyone have any other ideas or suggestions?

Thanking you all in anticipation. Linford will work one day. Honest!

[TimHaydnJones]

c'mon peeps - some of you must have an opinion

[EDLT]

I'm no expert on cars of that era (I assume it doesn't have a coolant temperature sensor), but hot-start problems are usually fuel related.

[TimHaydnJones]

Thanks for taking the time to reply, but this isn't a hot start issue - it's a 'cut-out-in-the-middle-of-normality' issue
I have replaced the fuel pump and in-line fuel filter.
I had considered something like 'vapour-lock' but, having experienced that in the past, it doesn't feel the same - when I've had fuel issues, they were normally prefixed by spluttering, but this is 'out like a light switch', which says electrical to me - but then what do I know? - I have never got to the bottom of it.

[EDLT]

In that case, check that there are no relays in places likely to get hot too.

[marshalla]

At the risk of asking the obvious - did you change the ignition leads ? I've experienced some horrible problems with leads which break down when they get warm.

Coil shouldn't really run that warm - possibly a ballast resistor issue ?

[anonymous-user]

Can't access the face book, is it a Twin Cam or a 900? either way the carbs/petrol would not cause ut out, it must be ignition, and as a general rule a coil to hot to touch is gone.
There is no reason you should not get a lotus reliable, I used an elan sprint and aeurope twin cam as daily drivers and raced a 900 sort out oil leeks and electrics and they are good engines,.

[Zad]

I suspect that sometime in the past, some bright apark (ho ho) has seen the ballast resistor and thought "ha, that's reducing the power getting to the coil, it's bound to go better if I bypass it" and removed it. I'm sure they shouldn't get 'hot' hot. It is bound to compromise the dielectric and wire insulation at some point. Check it is there and being used at any rate.

[TimHaydnJones]

It's a type 907 2 litre.
Anyone know whereabouts the ballast resister used to be located and what one looks like?

[TimHaydnJones]

OK, I think I've answered my question about what one looks like
http://classicsagogo.co.uk/acatalog/ballast_Lotus....
Are we saying that if fitted, there will be a wire direct from the coil to one of these jobbies?

So, Zad and Marshalla - if a car was supposed to have a ballast resistor fitted but doesn't have one - how would it be expected to behave?

[RobM77]

I had problems with a coil getting too hot on my Metro race car. To get the car to run I needed to re-site the coil away from the engine and then run a cooling pipe to it from a cold air pick up point above the headlight. It's a fairly common problem. Not sure if that helps or not!

[marshalla]

TimHaydnJones said:

OK, I think I've answered my question about what one looks like
http://classicsagogo.co.uk/acatalog/ballast_Lotus....
Are we saying that if fitted, there will be a wire direct from the coil to one of these jobbies?

So, Zad and Marshalla - if a car was supposed to have a ballast resistor fitted but doesn't have one - how would it be expected to behave?

Without a ballast resistor, too much current will pass through the coil and it will overheat and break down.

Tim - you might be better popping back across to the forum you've already joined where we can get into more detail on this if necessary.

Edited by marshalla on Saturday 6th November 09:57

[marshalla]

Of course, all this is assuming that you have a standard 6V coil - if it's a 12V I think you can ignore anything that's been said about ballast resistors.