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MG MGB Technical - Magnetronic Ignition System

Anyone fitted a lumenition magnetronic ignition system to an MGB(1978cc).

Just fitted one and also fitted the lumenition coil, followed instructions now cannnot get rid of misfire/ lumpy tickover. Do not think its carburettors.

Any ideas please?
steve

hi ive had many problems with electronic ignition.ive tried crane xr 600 and magnetronic,they seem to be complicated wirh external amps ,ballast resistors and different gizzmos .i was advised by peter burgess and went for a new dizzy by aldon and they sell a great very simple electronic ignition system which replaces the points . if the unit lets you down you can swop it with points in a few mins on the road side.i think its better to get rid of the old dizzy then you get rid of any cam ware .get on to the aldon web site and have alook . most the guys who race the mg go for this unit. i think that the problem is cam ware on a very old dizzy thanks daren
daren

Hi Steve,

i too have a luminition magnetronic ignition with the luminition coil fitted to 78 bgt,and had the same problems as you,poor performance.
what you need to do is to readjust the timing,if you have a timing gun then use it,disconnect the vacuum advance pipe on the carb manifold and cover hole then check timing and re-adjust,slacken of distributer and turn in small segments either clockwise or anticlockwise until you get the right timing.
if you don't have a timing gun then you can slacken of dissy,start engine and then turn dissy insmall segments until the engine runs smoothley or nearly smooth( it is a B series engine,so does not always run smoothly),
you do not need to adjust the carbs unless you are changing the air filters for K&N type.

HTH phil.
phil mcneil

I've got Magnetronic, but not coil. Engine starts better, but I'm not convinced that it goes better.

I recall the timing being way, way out after I fitted it too.

Neil
Neil Lock

sounds like when I fit a magnetronic, it ran horrid after fitting......I then realised that the plug leads had been put back wrong - doh!

1-3-4-2 anti-clockwise.

S Longstaff

The Magnetronic system is virtually the same as the Crane here in the States. It can play games with your tach and is difficult to install properly, but its a very reliable system. The Aldon system is the same as our pertronix. Its simple to install and as reliable as the Crane. You need to run a 12V power lead to a new 3 Ohm coil in the RB cars though. The stock coil or a Sport coil from a CB car will work too.

Steve, part of your problem may be the poor igniton curve that comes in the '78 dizzy. Try advancing your timing a few degrees from the stock setting!
Jeff
Jeff Schlemmer

Assuming its Hertfordshire, England, the distributor curve shouldn't be the problem anyway, and especially if the problem is bad running only *after* fitting a different ignition system!

Timing could well be way out as the trigger systems are vastly different.

I thought the issue with RB cars was that the trigger needed a full 12v supply as it can fail to trigger on, but the coil could remain and hence the ballast. There is nothing in the Manufacturers application data sheet that says RB MGBs (which have a different model to CBs because of the change of distributor from 25D to 45D) must have a different coil as well. Losing the 6v system and its boost function is a retrograde step.
Paul Hunt 2

This thread was discussed between 09/02/2007 and 11/02/2007

MG MGB Technical index

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