Bench test

Technical MGB discussion
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Steven collins
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Joined: Fri Oct 31, 2014 5:20 am
Forename: Steve
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Bench test

Post by Steven collins »

Is it possible to bench test an original 123 distributor and if so how?
Alternatively does anybody know where if possible I could get it tested/repaired.
Many thanks
Steve.
Ian Fozzard
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Re: Bench test

Post by Ian Fozzard »

Steve, I guess it depends on exactly what you want to test? I believe that most engine tuning companies/rolling roads would be able to plot out the advance curve, but the manufacturer would be the place to get a comprehensive test.
Look for local rolling roads and ask for advice.

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
Vic Butler
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Location: North West Hampshire

Re: Bench test

Post by Vic Butler »

Steve, have you tried the original supplier?. Personally I think the 123 is a waste of time. I fitted one to my Land Rover, set up per the book and it was down on power. I fitted the correct Lucas distributor equipped with Charles Kettering's antiquated points and condenser system, roughly timed it and power restored.
A misfire had developed with the 123 so I contacted the supplier who asked for its return. Fortunately they "lost" it and refunded my money which I used to have a proper Lucas distributor rebuilt and fitted with electronic ignition by the Distributor Doctor. I timed it by ear 10 years ago and have had no need to touch it since apart from the occasional lubrication.
1977 Stage 2 MGB GT
1975 SWB Series 3 Land Rover with a later 2.5 petrol engine
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Steven collins
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Re: Bench test

Post by Steven collins »

Ian, I had the 123 dizzy fitted to the B back in 2009 worked well for years, then last year the car was hard to start wouldn’t fire up straight away producing intermittent poor spark then when I rebuilt the engine earlier this year I messed up when refitting the dizzy - left a piece of metal in the cap 😥 didn’t improve the function of the dizzy strangely enough!!
Changed it back for original dizzy and points - so far working well.
Guess I would like to see if it can be repaired once I find out why it’s not working efficiently as when new.
Good as a spare part if working as I will not change it back whilst dizzy and points working well.
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Paul Hollingworth
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Re: Bench test

Post by Paul Hollingworth »

My friend and I fitted a 123 distributor to his B and it has been excellent. We set it to curve 2 which is the original 25D curve 40897. He had HS4 (later HS6) carbs but originally had a 45D distributor which just don't go. I couldn't justify spending £270 on a 123 for my old girl so I fitted the Luminition Mangnatronic electronic system from his old distributor. I had to pay £50 for a new baseplate and trigger disc to fit my 25D. It works fine but I haven't noticed much improvement over my old points set up but my distributor spindle bearings are quite worn. I didn't check my advance curve before but have since fitting the electronics and it seems to follow the published curve well. Just at the moment I've got my engine ticking over really smoothly which I'd struggled to do before but I'm thinking this is more to do with carb set up than ignition. I will buy a pirate pick up off E-bay before I do any Motorway journeys (£35 versus £90 for a pucker one). I don't fancy trying to retrofit points on the hard shoulder which would probably take half an hour. I could change pick-ups in 5 mins.
Incidentally, Distributor Doctor recons that cheap Chinese pick-ups as offered by some suppliers give too much scatter on timing.
1971 MGB roadster & 2006 MGTF
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