strange missing fault

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traumjaeger
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Joined: Mon May 15, 2017 3:04 pm

strange missing fault

#1 Post by traumjaeger » Mon May 15, 2017 4:13 pm

Hi all,
I have a1965 Humber Sceptre MK1 which has an annoying fault. The car has been upgraded to electronic ignition and has a new fuel pump and Weber carburettor. The car starts and runs well but occasionally when driving along the car starts to miss and acts like a kangaroo. I may have driven for miles with no problem then all of a sudden the missing starts. There is no specific situation occurring which would give me a clue to the problem. I really don't know where to start fault finding, electrics or fuel. Can anyone out there suggest a possible cause?
Many thanks
Regards
T

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Luxobarge
Posts: 1783
Joined: Wed Jan 05, 2011 3:12 pm
Location: Horne, Surreyshire

Re: strange missing fault

#2 Post by Luxobarge » Mon May 15, 2017 7:34 pm

Welcome to the forum.

Tell us more about the ignition system - what sort of electronic ignition is it? If it's one that retains the use of the distributor cap and rotor, I'd be suspecting those components. And don't say it can't be because they are new - there are LOTS of really carp quality ignition components out there, only really good original quality ones will do. I'd particularly suspect the rotor arm - assuming it has one.

Hope this helps?
Some people are like Slinkies - they serve no useful purpose, but they still bring a smile to your face when you push them downstairs.

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JPB
Posts: 9818
Joined: Fri Jan 07, 2011 3:24 pm

Re: strange missing fault

#3 Post by JPB » Mon May 15, 2017 8:53 pm

^^^^^

Seconded. :thumbs:


Also, if you don't mind your car being drooled over by a whole load of old car fetishists, would there be any chance of seeing some pictures of the Humber please?

8-)
John, If it's old & badly broken, chances are I've owned it. :|

traumjaeger
Posts: 8
Joined: Mon May 15, 2017 3:04 pm

Re: strange missing fault

#4 Post by traumjaeger » Tue May 16, 2017 5:52 am

Hi John,
No I would love to post some photos of my car but at present I don't have any but will post some as soon as I can get my wife to get her camera organised for me, so please be patient and all will be revealed.
T

traumjaeger
Posts: 8
Joined: Mon May 15, 2017 3:04 pm

Re: strange missing fault

#5 Post by traumjaeger » Tue May 16, 2017 6:03 am

Thanks for the welcome Luxo. The ignition is a Petronix set up. The dizzy cap is a new old stock Lucas item as well as the rotor. There are no signs of any cracks or burn marks on the cap and the rotor is not loose in it's housing.
By the way one thing I forgot to mention in my initial blog was, that after the missing clears the car runs fine again for many more miles.
What can I do to check out your theory of the ignition being at fault apart from changing it all back to standard points, which I don't want to do?
This problem is really bugging me.
Thanks again for your reply
Regards
T

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JPB
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Joined: Fri Jan 07, 2011 3:24 pm

Re: strange missing fault

#6 Post by JPB » Tue May 16, 2017 7:03 am

Pertronix was marketed in the UK as the Aldon Ignitor, though the Californian manufacturer also made a cheaper, magnetically triggered version and those cause the symptoms you described. I had three in succession from Pertronix themselves, as the Aldon branded version cost some twice as much at the time, all developed the fault, thought at the time to have been caused by heatsoak as the supplied paste wasn't up to the job where the trigger unit was attached to the distributor baseplate. This was on a 750cc Reliant Rebel, the car ran perfectly again once I'd fitted a £10 device supplied by a Land Rover specialist and used some decent Dow-Corning paste to make sure that it didn't suffer with overheating. That one lasted a whole year, which in that car equated to 32,000 miles and was replaced with another as that was cheaper than replacing the points and sourcing a decent capacitor from Sovcom, whose military spec Teflon caps are what I always use to replace standard ignition condensers. The car is long since dead, but that engine lives on in another Rebel and had, last time its current owner was in touch, covered a further 70k on another of the cheap Britpart ignition kits.
Were I to do it all again, I'd stick to points and a good capacitor upgrade from Sovcom since nearly all new condensers leak as a result of lack of demand which leads to lengthy periods of inactivity. Even when I was running an electronic setup, I always carried a spare distributor baseplate, points ready gapped, so that a quick swap could be made by the side of the road when the electronic device died. Note that I say "when", there's no "if" about it! ;)
John, If it's old & badly broken, chances are I've owned it. :|

traumjaeger
Posts: 8
Joined: Mon May 15, 2017 3:04 pm

Re: strange missing fault

#7 Post by traumjaeger » Tue May 16, 2017 9:08 am

HI John, some clarification please. You say that your electronic ignition died and you changed it at the side of the road back to points. My system doesn't actually die but starts suddenly as a severe miss which after short period clears and the car runs normally again. I never know when its going to happen but its usually when my wife drives and she really gets annoyed with it. I don't want to change back to points if I can help it.
Thanks
T

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JPB
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Re: strange missing fault

#8 Post by JPB » Tue May 16, 2017 12:40 pm

Hi T,
Yes these things tended to be somewhat erratic for a short time, then, one day, the car would stop entirely and so I carried a spare baseplate, with ready gapped contacts and a fresh, new high quality capacitor, other distributor types' contacts may be fitted to separate parts of a split baseplate and in that case, then the contacts will need to be gapped at the time of fitting, but carrying a (typically 0.016") feeler blade will get the gap at least good enough to get you running reliably again, until you have a dwell meter to hand. (in my case the car had a Lucas 43D4 distributor, but any Lucas distributor and many other makes too can equally easily be swapped back to points in the event of ignition sensor and/or amplifier failure).
The only real reliability issues with contact breaker ignition comes from the uncertainty that exists these days concerning how long the condenser is likely to last or indeed whether it will be capable of maintaining its potential in use, other components can be found wanting and some, such as the rotor arm, will affect electronic and contact breaker systems similarly so avoid old stock condensers, avoid an arm that has a riveted contact in combination with a thermoplastic substrate as these leak to earth, Phenolic or Urea formaldehyde (Bakelite) arms are fine and will keep their insulating ability when warm and even when they're ancient so buy up old ones at autojumbles and other venues where these are available, same with distributor caps, but replace condensers with compatible (0.22uF or 0.47uF @>/=630WV) new capacitors that can either be fitted externally to the distributor or, as I do with Lucas ones, in the original can, which is large enough for a typical, modern capacitor of suitable value in either Teflon, Polypropylene or ceramic. A higher working voltage is fine, I can supply these but Sovcom sell them for far less and they ship much more quickly.
Try each value and decide which is the better match for your coil by looking at the physical condition of the points' faces, a condenser with too much capacitance will cause a deposit on the mounting side of the points. A condenser of too little capacitance will cause a deposit on the arm side of the points. Ideally, you don't want to see this symptom in either direction for at least the interval between services.
John, If it's old & badly broken, chances are I've owned it. :|

kevin
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Joined: Sun May 12, 2013 7:49 am

Re: strange missing fault

#9 Post by kevin » Tue May 16, 2017 6:55 pm

A few years back, during the period following my singers recommision, I had a very similar experience.
My problems turned out to be the lucas electronic ignition. Fitted sometime in the 1970s it would run fine then start to break down, giving the impressions of a fuel problem.
Eventually gave up the ghost in my garage 😀
As a stop gap I fitted an accuspark distributor, £59 delivered, but it was only needed for that weekend until the NOS distributor arrived. Fitted, timed in and the singer runs faultless.
That was a few years back and the NOS distributor sits on the shelf and won't be fitted unless something drastic happens.
Worth a try for the money and will help eliminate that potential problem?

Kevin

Penguin45
Posts: 174
Joined: Wed Jan 19, 2011 7:39 pm

Re: strange missing fault

#10 Post by Penguin45 » Tue May 16, 2017 11:21 pm

I've had nowt but trouble with these "Hall Effect" trigger systems. The heat seems to get them quite quickly.,

P45.

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