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MG MGB Technical - Electronic Ignition Question

Have a '74 1/2 GT four cylinder. Wish to put in new distributor and electronic ignition. Any recommendations on brand or? Thanks!
JW Colson

The most poplar conversion seems to be a pertronix.
That said, I have used a Crane Allison since early 79, it has worked great for me. You do have to mount the ignition box outside the distributor, the Pertronix is inside the distributor.

Clifton Gordon

WE, [BMC-British] have installed many of the Pertronix.
Just did one this last week in a early MGA.
Runs nice...........

DCM McCullough

Pertronix now sells a FLANE THROWER PERFORMANCE DISTRIBUTOR that incorporates their electronic ignition into a new distributor. While not yet in the Moss catalog, it is sold by both them and Little British Car Co. I am thinking of buying it, so would love to here comments from those who already have.
Bob R.

Recomendations? Stick with points! If you must fit electronic make sure you carry points and a condenser with you and can retro-fit them at the roadside. Points problems usually give warning and can usually be fixed at the roadside, electronic systems usually fail suddenly and totally and can only be fixed by substitution.
Paul Hunt 2

I always follow Paul Hunt's advice (well almost always) and I've never gone wrong yet. Still waiting for him to set up his workshop in Sydney, Australia btw.

I use the Lumenition Magnetron Electronic Ignition. They market it as the "entry level" or budget system, but in my opinion it is far simpler and therefore less likely to fail than most of the expensive and complicated systems.

You fit it inside your existing distributor and once in place everything still looks original or factory. As long as the shaft on your old distributor is not bent or worn, you remove the condensor and points and replace it with the Magnetron parts (so simple ANYONE can do it... even me).

Definitely, definitely, definitely... keep the old points and condensor in your trunk or glove box for emergencies. If the Magnetron ever fails you can swap the old gear back in and you're on your way. In more than 3 years I've had nothing go wrong with mine at all, but I did have another problem which in order to rule everything else out I replaced the old condensor and points just to know exactly what I was dealing with. Once the problem I was dealing with was fixed, the Magnetron went straight back in.

BTW - I've not had to adjust my timing ever since I installed it. Admittedly you should never need to adjust it with condensor/points either (according to Paul) but for the life of me I could never get mine to be that reliable.

If the Lumenition Magnetron is not available anymore (they wouldn't would they?!?) then I don't know what else to recommend. If not for the simplicity of the Magnetron I'd be staying with condensor and points... and getting Paul Hunt to set my timing for me. :)

Sydney, Australia
D O'Brien

MGOC still advertise Magnetronic, and Optronic which has an optical trigger under the cap with an external switching module.

Planning to visit Oz in about 4 years, David, to celebrate our 40th anniversary :o)
Paul Hunt 2

I've always used the Lumenition Optronic on my race cars and never had any reliability issues.
Road cars have always had points.
I did once try a Lucas TAC5 unit, in conjunction with points, but it died!
Dave O'Neill

I've solds about a dozen of the Pertronix Flame Thrower distributors, and they work very well. Its a repaired version of Moss's 45D replacement distributor. Of all the Flame Throwers I've sold, they have virtually all had a different ignition curve, so I recurve every one that passes through the shop to suit each engine.

With that said, for less than the cost of the Pertronix, your original dizzy can be rebuilt, recurved, and have a pertronix kit installed. Points can be installed in either unit.
Jeff Schlemmer

Could someone explain what it means. to recurve a distributor.
Bob R.

Bob. To recurve the distribiutor you have to have some way to test what the current mechanical advance curve is. Then, you alter the advance stop on the points cam, as necessary, to give you the proper overall mechanical advance. They, you play with springs so that the mechanical advance is correct at various engine rpms. A somewhat labor intensive process and best done on a distributor test machine.

Ideally, the car is put on a chassis dynamometer, a rolling road to our Brit friends, and the best possible advance curve for that specific engine is plotted. Then, with those figures in hand, the distributor is sent off to a competent craftsman who will make the mechanical advance is close to that ideal curve as is physically possible. At that point, the distributor can be installed and the engine timed to suit the advance curve of the distributor.

Hope this helps.

Les Bengtson

I can vouch for the reliability of the Crane system. I installed one on my Volvo in 1988, and I've driven it well over 100,000 miles since then. No repairs, no adjustments, no attention paid to it at all. It just works, always. It outlasted the engine I put it on, I moved it to the new engine, and it's still going. Never heard of one failing. I don't even carry spare points anymore; I know that my ignition will never die on me, and that's that. Needless to say, I'm absolutely happy with it.

This thread was discussed between 26/11/2006 and 02/12/2006

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