Yet more woes

Technical MGB discussion
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Steven collins
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Yet more woes

Post by Steven collins » Mon May 04, 2020 6:53 pm

Everything was rosy this morning - then I started work on the car 😱
I “lost” the choke trunnions the other day, but a fellow MGer was kind enough to post one on to me, having arrived this morning I promptly fitted it to the choke (choke now works better than its ever done) all good so far—-
Started engine good oil pressure then a bit of back firing from carbs then 😥car cut out tried to restart but not firing.
Took out a plug to check spark - no spark
Took off 123 ignition cap - oh S?1t - “lost” trunnion had somehow got in the cap!!
I am assuming that the trunnion being in the cap with a rotating rotor arm has messed up the electronic ignition hence no spark
Does anyone know of a company that will repair said 123 dizzy for less than a new one?

Ian Fozzard
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Re: Yet more woes

Post by Ian Fozzard » Mon May 04, 2020 7:42 pm

Well, that's one for the record books - the most improbable combination of mishaps☹️. My sympathy....

I am not familiar with the workings of the 123 distributor, but it would seem it may just be some slight mechanical damage? Can you see a broken wire or a damaged component?

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Steven collins
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Re: Yet more woes

Post by Steven collins » Mon May 04, 2020 11:29 pm

Not sure as it’s difficult to see directly, I did look at the cap and this appeared damaged inside at the back of the contacts. Some of the plastic which holds them into position had broken away.

Ian Fozzard
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Re: Yet more woes

Post by Ian Fozzard » Tue May 05, 2020 8:13 am

Steven, is it a standard cap which fits this distributor? If so, I would try replacing that first if that's where the damage can be seen. The distributor caps are relatively cheap - you may even have an old one lying around somewhere??

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

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Charles Farran
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Location: Warwickshire

Re: Yet more woes

Post by Charles Farran » Tue May 05, 2020 9:18 am

Steven,

I have a 123 Distributor on my 1980 Roadster & have had it for at least 10 years . I believe there are at least two distributor caps as i replaced mine approx 3 years ago. My 123 was not the variable programmable one that you can now get which enable drivers to vary the timing at the click of a button if changing from track driving to driving home. The caps are different & when reordering from MGOC in this instance i had to tell then if it was before or after a particular year. (2013 springs to mind but i may be wrong. Your rotor arm may be damaged as well & that might have been altered as well, so that maybe year specific as well.(My 123 just required setting at the particular setting point as specified by the particular MGB engine in my car).
May be a worthwhile spending a modest amount on a new cap & rotor arm first before assuming the worst!
Cheers
Charles
1980 Roadster

Steven collins
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Re: Yet more woes

Post by Steven collins » Tue May 05, 2020 9:28 am

Charles spot on, I looked at the distributor again this morning the rotor arm key way inside was damaged and misshapen, I cleaned this up and put it back into shape as best I could cleaned the contacts on the cap again and refitted. Car thankfully started, she is running rough but the carbs need tuning up so not surprised.
I will order a new cap and rotor arm, thanks for the heads up about year specific will look through my paper work to see when I purchased it which is probably around 9/10 years ago. It is also the non programmable one.

ChargedAutoGT
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Re: Yet more woes

Post by ChargedAutoGT » Sat May 09, 2020 10:52 pm

Lucas caps/rotors do not fit the 123. Pity as they are far cheaper.
G

Steven collins
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Re: Yet more woes

Post by Steven collins » Sat May 09, 2020 11:09 pm

Hmm, yes don’t I know it —— just under £27 for a cap & rotor arm!!

Vic Butler
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Location: North West Hampshire

Re: Yet more woes

Post by Vic Butler » Sun May 10, 2020 8:32 am

I had a 123 distributor on my Land Rover. It was worse than the old points system despite my following the installation instructions to the letter, and then the engine developed a misfire. The supplier asked me to return the distributor and they conveniently lost it so I had a refund. I used a standard points distributor in the meantime and performance was restored.
The Distributor Doctor rebuilt a used Land Rover distributor and fitted it with Petronix electronic ignition for less than the cost of a 123. I fitted it, timed the engine dynamically by ear, and haven't touched it since apart from the occasional drop of oil. That was in 2010. The Doctor's distributor caps and red rotor arms are the best.
The 123 distributor doesn't give enough advance for low compression engines (8:1 for the Land Rover.)
My Stage 2 BGT has a distributor built by the Doctor to suit the engine modifications.
1977 Stage 2 MGB GT
1975 SWB Series 3 Land Rover with a later 2.5 petrol engine

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