The Triumph Dolomite Club - Discussion Forum

I know I may get a slating for this posting but I have a problem with a 1500 Midget. I know how helpful you all are, so thought I would ask on here.

We are in the early stages of getting it ready for racing but it has an intermittent problem which seems to be a misfire. At the moment it will run fine for about 8 -10 miles then it will begin to run roughly and sometimes cut out. The previous owner has told us that it was blighted by this problem when he had it. We suspected the coil and changed this for a known good secondhand one (which with hindsight may have been 12 volt) but it made no difference and the previous owner, it turned out, had already had a new one fitted before.

I am thinking off fitting an Accuspark electronic ignition kit which consists of a distributor, pick up, cap, rotor arm, high performance leads, three electrode plugs and a sports coil. This should eliminate all of the ignition components being at fault and will be a useful upgrade too. Their coil is compatible with the ballast resistor.

I wanted to ask, what is the feed from the starter solenoid to the positive terminal of the coil for? Does this provide 12v during cranking? Also, is it worth removing the ballast resistor and running a 12 volt system?

At the moment the engine is running in standard tune apart from pancake air-filters, AAQ needles, yellow springs and a single silencer exhaust. More modifications are planned when we get some funds together.

Thanks,

Glen.

If it only starts after a while, is it possible it's fuel, not ignition? Also, does the car have to cool right down before it goes away, and if not, is it different when the car's started again when it's only half cooled?

Graham

GlenM wrote:...

I wanted to ask, what is the feed from the starter solenoid to the positive terminal of the coil for? Does this provide 12v during cranking?

Thanks,

Glen.

Yes, the coil will run at 6 - 9 volts when the engine is not being cranked.

GlenM wrote:...
Also, is it worth removing the ballast resistor and running a 12 volt system?...

Thanks,

Glen.

Yes, remove the ballast resistor and with the Accuspark upgrade fit a 12V coil.

Jeroen still prefers a ballasted system, but the full 12v option is much simpler.

Its all here...

https://www.dollywiki.co.uk/wiki/Igniti ... ss_removal

How to get rid of the ballast and why you might want to.

Your current problem could well be your condensor breaking down as it warms up.

Britpart kits are cheap and work well.

AAQ's will be a bit rich on a midget with its more restrictive exhaust. Try ADH.

Jonners

The Midget should be fairly easy to diagnose with a problem like this.
Does the rev; counter immediately drop to zero when the problem happens and the engine is running down to a standstill ? If so its probably L.T. electrics. Also have a look at the thin braided earthing wire that runs from the distributor baseplate to the fixing screw on the side. If the rev; counter continues to work have a look at H.T. electrics; A faulty HT lead from the coil to the distributor will stop the engine. Faulty plug leads will only cause rough running.
If you have a Midget with the electric SU fuel pump does it continue to tick from time to time when the engine has stopped ? If so I'd check for fuel flow going into the carbs; No fuel with the pump ticking = blockage or suction side air leak. No ticking ; I'd check electrics to the pump and the pump points under the cap.
I had an unusual problem on my "B" soon after replacing the ignition switch. The ignition light would come on and the engine would stop, rev counter dropped straight away. Hint: The replacement IGN switch wasn't made by Mr Lucas. I found the crimps on the connector hadn't been made properly and would just pull-out. I soldered them in the end.
Tony.

Graham, I thought it might be fuel related before. A few weeks ago it was missing when I had it on the drive at home, so I turned it off and checked the float chambers and there was plenty of fuel in them. I did check the fuel pump diaphragm, which was fine, and I fitted a new in-line fuel filter. I did literally a couple of miles in it after and it seemed to be ok.

On Friday evening I did a round trip of about 8 or 9 miles to collect my daughter, the car ran really well, then just as I turned back into our village it began to hiccup and splutter but we just got home.

Yesterday I was Best Man at a friends wedding and I was due to drive him to the church in the Midget. The car started fine and again ran really well but about a mile from his house (8 or 9 miles into the journey again) it spluttered and died a few times and was difficult to get re-started. I got to his house, we took a coil off of his Minor (in our wedding suits), put it on and the Midget fired up. However, it began miss-firing and spluttering just 100 yards down the road, so we abandoned it and went in another car.

I have just been to collect it and it fired up first time with no problems, did the same return journey, it ran absolutely fine, then a mile from my house had the same problem again.

If it was fuel related I would have thought that it would be spluttering more under load - when accelerating hard, or going up a hill. It seems to be much more temperature related than load related, as when it is playing up it will start to die if you just blip the throttle. It hasn't yet played up, then cleared and completed the rest of the journey running fine again.

Tony, the rev counter doesn't drop straight away when it runs roughly, only if the engine dies completely. The distributor earth was checked by the previous owner's mechanic but I will look at again. It is a mechanical fuel pump on this car.

As I say, I may as well just replace the whole ignition system with the Accuspark electronic ignition kit.

Water in the petrol tank?

Jonners, thanks for the link, that explains it all.

Is there a particular web-site that you can recommend, to look at the cost of the Britpart kit?

Appreciate that the AAQ needles might be a little rich at the moment. We are currently running the standard system with the large rear box removed but we will be getting a four branch manifold and system soon, so the needles have been selected to be ready for that. According to what I have read, it is purely the 4-2-1 cast manifold on the Midget that causes it to be rated at 5 BHP less than the Spitfire. A 4-2-1 tubular manifold is supposed to make a huge difference on the Midget.

soe8m wrote:Water in the petrol tank?

Maybe, if it did it all the time but it only does it when the engine is up to temperature (after 8 - 9 miles). It will then start fine again if left for a few hours.

Check the fuel tank breather and possibly the filler cap to make sure it is vented, other than that, I agree with Jonners, it's probably condenser related, I had a similar problem with an early Passat I owned which ran fine till hot when it suddenly developed an allergy to hills. It took me a week or more of repeated carb and fuel pump stripdowns before I went back to basics (which I should have done from the start) and replaced the ignition LT components, hey presto, no more problem!

Steve

I was also going to suggest that you took the petrol filler cap off next time it happened to check that air was able to get into the petrol tank. If as you remove the filler cap you hear air being drawn in you have found the problem. I had been using the same locking filler cap for a number of years on one of my dolomites before it decide to make a perfect seal that prevented air getting into the tank. The result was the engine would cut out due to the pump not being able to draw sufficient petrol from the tank. I cut a groove across the rubber seal in the petrol tank and the problem was solved.

Havent bought a Britpart for a while now but one of the Land Rover sites M + M 4x4 seemed pretty good. Some Landies
have a similar distributor.

I lost about 5mpg when I swapped to the Triumphtune flangeless manifold with the twin boxes on my Spit. You do pay a price for the extra go...

Jonners

Jon Tilson wrote:Havent bought a Britpart for a while now but one of the Land Rover sites M + M 4x4 seemed pretty good. Some Landies
have a similar distributor.

I lost about 5mpg when I swapped to the Triumphtune flangeless manifold with the twin boxes on my Spit. You do pay a price for the extra go...

Jonners

Thanks, I will take a look.

If you get extra go you do tend to use it, especially if it sounds nicer too. Loss of MPG is not going to be an issue, ultimately it will be an occasional fast road/race car.

Here's the Britpart electronic ignition kit. I've got this fitted to a Sprint dizzy on my 1850 and it hasn't given me a moment's bother since I fitted it. Well worth every penny. It is a straight swap for the points and condenser and you can keep your existing coil.