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MG Midget and Sprite Technical - HT Leads advises for beginner

Good morning !

Hope you all enjoyed your long weekend ! And had a chance to make "essential" shopping with your Spridget :)

I did it with mine, and as I start to know her more and more, I did notice that the car rev counter was "jumping" from time to time, +/- 500rpm. Hard to tell if I had it before or not, hard to find any "pattern" for when this to happen... Anyway, distributor caps and HT leads were always suspicious to me (don't know why...) and I decided to have a closer look at them during my tea break :)

Conclusions:
The 4 HT leads to spark plugs all have around 6k Ohm resistance
The number 3 looked not so nice compare to others, at both ends with surface corrosion on the connector and the screw.
The HT lead between coil and distributor cap is pretty "bad": a cut in it, and around 30k Ohm resistance

Questions :)
- I never changed HT leads and I have no idea what kind of tools I need, or which parts to buy... To my view, I would change the number 3 connector to spark plug, and the "coil to distributor cap" lead and connector
> Would you do the same ?
> Which tools do I need ?
> Which parts would you buy ?

Might sound like "HT for dummies" questions, but I assume I never did to any car... As it is almost routine for you I guess :p
Thanks !






CH Hamon

Cedric,
you have possibly found the misfire you're car has had for a while.

You could cut out the split section and reconnect the, er, connector. Or you can buy individual HT leads and just replace the one(s) you think is/are faulty.

Some say HT leads last for decades so why replace them.

But a set of 5 you can get so cheap why would you not replace the whole set.

You need a suitable screwdriver for the dissy cap screws, a hand and at least one good eye. The screws need to go through the insulation to contact the core 'wire'.

What is the condition of your dissy cap and rotor are they fully functioning and do not need replacing?

It is a pity that you were not advised to check these at say a service or to replace sooner, someone should have advised you.
Nigel Atkins

As Nigel says, just get a new set, they're as cheap as chips----Just be aware that if you're getting resistor leads like you have now, some have a metal end for the screw in the cap to screw up against and some don't--IF you happen to get a set without you need to push a pin into the end of each one otherwise the screw can loose contact with the core and it will burn there and will fail early
William Revit

Cedric,
The rev counter needle "jumping" can be an indication of a fault with the ignition circuit, but not the HT side of things. It shows up low tension faults. That's not to say that your HT leads etc are OK, but don't take the jumping needle as an indication of this. It may suggest another fault elsewhere. Or it may just be a sticking needle in the rev counter as ignition faults would normally make the needdle flicker quite violently.
GuyW

Nigel, just tried to shorter the lead from coil to distributor, and I still have 30k Ohm...

Regarding the connectors, that is where I am a bit lost... Mines are without the push pin, just the screw. And I think it is what damaged the number 3 earlier than others... Would you mind showing some examples Willy ?
Also, don't I need a special tool to crimp the connectors ? The one on the coil or spark plug side looks well put...

Thanks for the advise Guy. I see what you mean... When people are talking about "rev counter jumping", of how much rpm roughly are we talking about ? Maximum range I have seen on mine is 1 000rpm (current rpm and oscillating +/- 500rpm). Maybe I miss-interpret it (hopefully :p).

Do you guys recommend any specific supplier ?
CH Hamon

Did you test the testing equipment before carrying out the test, is the testing equipment and tester reliable.

Yes there will be a crimping tool but a pair of pliers will also do the job. Why buy new leads when they last decades as other say. So the connector has to be bent twice more to get it off and back on again I am sure it will not suffer too much fatigue and it will be a repair rather than replacement that you will have the joy of knowing you repaired it.

But do not let your girlfriend know in case you need to do so again after you have stopped the car for another adventure of a roadside repair which for some unknown reason she does not appreciate.

The Powerspark leads *look* alright, the Ferroflex material is good, I do not know about the quality of assembly depends who does it for them. I think Gary bought some.

Willy *I think* means a cap comes with the lead (I've never seen those though) or you yourself push some pins/tacks/small nails into the centre of open cut ends of the leads to be fixed in the dissy.

Whatever you do do not check or change the dissy cap or rotor as this potential spending is getting out of hand!
Nigel Atkins

Cedric the screw in the cap isn't going to make the sparkplug end of the lead fail, what you have there is simply a broken spring clip

The pin
What I'm talking about there is where the lead pushes into the cap and then the screw inside the cap screws into it, the end of the lead that pushes in needs a pin up the middle to get a good permanent contact with the screw some leads have a metal end for this purpouse, some don't
Sounds like you need a new coil lead and a No3 so just treat it to a new set
When /if you're trying to fix the end of a resistor lead you need 1/2" of core poking out the end to double over to go in the lug to get a good contact , otherwise it won't last
William Revit

Surface corrosion on the connector and the screw could be cleaned off, think of the pride you would get.

Even the bits of string sets are £8.95 then there's P&P.

Terminals! That's the word I could not think of, terminals and boots, you can buy terminals and boots and loose lead to make up your own custom lengths sets (or you can cut the cut ends of the standards sets to custom length if they are long enough).
Nigel Atkins

dont know if this will help when i fitted a new set of leads a couple of years ago wrote down the resistance of each lead before i fit them.
main 1978 ohms
1. 1066 ohms
2. 1083 ohms
3. 1234 ohms
4. 1461 ohms
all insulation greater than 1000 megohms
mark heyworth

The tach issue is possibly internal. It has an electronic circuit with ageing componens, especially capacitors which tend to fail or change in value after several years. You might have a failing "condenser" (a capacitor really) in the distributor. Is it an RVI or RVC tach (will say on the face)?
Bill Bretherton

I thought people always buy the wire and connectors/terminals separately, and then you assemble them. Like what we do for electrical wiring on the car...

RVI ! I did notice in fact that when I change down a gear on a "sporty2 drive, the rev counter needle is in fact jumping a lot....

I continue with stupid question... I have an electronic ignition (lumenition): do I still have a condenser then ?

CH Hamon

My rev counter has the odd jump about sometimes - I think its due to electronic ignition.
Have read that a 'clean' supply to the tac can help but not bothered.
The RV1 is I understand it more prone than the later RVC which i have and both of them I have do the occasional bounce.
richard b

There was a thread about spark plug leads on MGexp a few weeks ago, where it was asserted that carbon leads and screw caps don't match. Kelvin Dodd weighed in with his (considerable) experience,

"As noted above, carbon core wires can be used with side entry caps. Back when I was working on the (Moss USA) parts counter, we sold the regular plug on Lucas wire sets for earlier applications and just cut the cap plugs off. They worked fine.
A suggestion, if you are have any concerns is to insert a piece of solid copper wire into the carbon core, so the screw in the cap has a better purchase.

This has become more of an issue of late, as internally damaged copper core wires have been believed to cause problems with pertronix electronic ignitions. Note the damage is caused by wires that have poor internal connections which cause damaging spikes.

Kelvin."

the MGExp thread is here

https://www.mgexp.com/forum/mga-forum.2/silicon-ht-leads-with-side-entry-cap.4132791/

I have used carbon core wires with screw side entry caps for over thirty years, absolutely no problem ever. Even without inserting bits of copper wire or any pins.

So if you have electronic points and are getting such spikes, a new set of cables is definitely required before you need to buy a new one. And Kelvin's suggestion to buy the push-on cap leads and cut the ends off is a good one, as the push on wires are usually lower cost due to greater demand.

And no condenser is usually the status with an electronic points system.
Dominic Clancy

Thanks Dominic for these informations. As I thought, HT leads are a more complicated subject than it looks like... Glad I posted here first, again :)

I also found this, where people suggest that copper leads might not work with every electronic ignition: https://www.mgexp.com/forum/mg-midget-forum.3/ignition-leads-best-to-use.3945442.3947126/

I bought a set of carbon wires for £9. Maybe when they break, I will by then have learned how to build my own copper ones !

Richard, I will leave it like this then :) I prefer a jumpy needle than no needle at all ;)
CH Hamon

Cedric,
you had the opportunity to improve, but instead you acted like a typical tight-fisted classic car owner. You have bought cheap.

You might need a needle threader for them when they arrive, at least there will be no worry about getting them through the letterbox.

The last set of those I got for free and I was still overcharged.

It would be best if you went the whole hog and took that Luminintion and got back to good ole CB points and, as Bill rightly calls it, capacitor setting the points as a proper classic owner should.

Making up copper cables! - you been watching Jean-Luc wiring a factory video!
Nigel Atkins

Be nice Nigel! :)

I have made the same sort of mistake in the past buying cheap, to then have to buy again later. (Brake switch for example) Its all part of the learning curve.

I think some of the experienced members of the forum forget just how much experience and knowledge they have, and how little us new comers have :)



Chris Madge

Expensive doesn't always mean quality, and cheap doesn't always rimes with sh*t ;)

I don't buy my cucumbers at Waitrose :p
CH Hamon

I think you'll be better off with carbon leads. In the past I've made up copper leads till I tried to time the car and was left with a blurr of scatter. The guys at the rolling road explained copper leads produce white noise and they always swop to carbon when setting up a car.
f pollock

Chris,
I think Cedric can take it, he's meet me in person three times now so knows what I'm like.

My thing is that I too have not much knowledge (loads of experience) which is why I just stress the basics from the very beginning and can see more of a beginner's point of view but perhaps I'm losing that.

Cedric's had a Midget (or two) for about two years now so should have covered some of the basics well before now, as I put before vous pouvez conduire un cheval à l'eau (those ditchfinder tyres!, carb fiddling). Cedric can take verbal ar*e-kicking and give some back.

I will say you're right that I was caught out by Cedric thinking you had to made the leads up rather than buy them in sets but I thought the lines about the cheap leads needing a needle threader and getting through the letterbox and the Jean-Luc reference were quite good, perhaps I should have put smiley face symbols.
Nigel Atkins

Cedric,
I am sure your cheap leads will do the job just that with the photo of your HT lead coil side the lead does not appear to be that old yet it has that split that would be under the neck of the boot. I suppose it could be damage caused by, and I am not saying you, but someone. My thinking, which may as it often is, be totally wrong is that lead is not as robust as perhaps some others and the cheap leads I have seen appear to be the same.

I agree with you cheap is not always to do with price but an item that is short lived could turn out to be the more expensive overall.

On the rev counter, as has been put it may be entirely separate to your misfire, my rev counter always now needs a tap on the glass to get it moving from starting the engine otherwise if I pull off without doing so the needle will suddenly violently swing up and bounce around.

At one time for a period the needle did not stick at the start, I have no idea why, but then it returned to sticking, again I have no idea why, but now it seems to always stick whereas previously sometimes/often(I can't remember) it would not stick from starting the engine.

I think it may be that I had the leads made too short. :)

Obviously I am joking but I did have the leads made up to custom lengths (I have a 123 dissy with cap with side push-on terminals).
Nigel Atkins

Cedric

Nigel's often given advice on getting the basics right, including carrying out a full service according to the Driver's Handbook, is good. And doing this before modifying so you have the standard specification and set up properly as a known baseline that works. Also these days we have problems with the availability of new parts that are of good quality (old days you could buy poor quality parts too, just there were also OK ones more readily available).

If you do take off old parts that seem OK, keep them safely as spares.

Old days I would have said buy Unipart plug leads as good value (good quality and price) - these days who? What does Minispares supply or Magic Midget? For my MkII Sprite I have used a new old stock Ripaults set of leads cut to length from an ex military supplier - but only good for the earlier distributor caps with leads that are anchored by a grub screw, not a cap.

For distributor parts the Distributor Doctor comes recommended, e.g. for rotor arms. Old days I would buy Lucas, but modern Lucas is not the same quality (and in the old days I was never hugely impressed - our colleagues in USA talk of 'Lucas Smoke'!) I would fit new genuine points at every service because I could as they were readily available and good value.

Best wishes
Mike
M Wood

This thread was discussed between 26/05/2020 and 28/05/2020

MG Midget and Sprite Technical index

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