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MG MGA - MGA /MGB distributor

I suppose that this question is not strictly speaking an MGA one but Im hoping someone out there knows the answer.
My MGB has a 3 bearing MGB engine fitted which runs very well with a pertronix electronic distributor (no vacuum advance) and matching "flamethrower" coil. I realise that if an electronic ignition system fails then there is usually no way to fix it and a replacement is the only way to go.
So I have considered buying a standard MGB dizzy complete with points to carry in case of breakdown especially for long journeys. (I always carry a spare coil)
Then I recalled that I have a 1600 dizzy amongst my spares which maybe I could fix up.

Would the 1600 dizzy fit the MGB engine and also would it run well enough to get me home without damaging anything?

Thanks
Colyn
Colyn Firth

Yes. The MGB block and the MGA block are interchangeable. Most use the original dizzy when they change to a 3 main B block in a MGA. Did you mean to say your MGA has a MGB engine?
R J Brown

Sorry RJ, yes I meant to say that my MGA has an MGB engine, I must be too busy concentrating on my sandwich to check my the wording. Its my lunch break and I was trying to multi task. I suppose I will have to blow the crumbs off the keypad next!
Thanks
Colyn
Colyn Firth

Colyn

RJ is the knowledge on this topic.

If you have a known distributor then you are likely to have no problem. By 'known' I mean one that you have previously used or know the history. The problem could arise when buying at an autojumble. Although the distributor may look the same externally, the internals could be optimised for another engine. i.e. the mechanical advance lobe and the springs may be different.

I had such a problem when my 1500 distributor came back from a 'professional' rebuild. It had the wrong advance lobe deep down inside the workings; 7 degrees instead of about 12 degrees. This would then only give me 22 degrees of mechanical advance (7 x 2 + static) instead of the desired 32 degrees (12 x 2 + static). The engine ran horribly flat.

Steve
Steve Gyles

Thanks Steve, I just wasnt sure if the advance curve on the 1600 dizzy would be ok to use with the 3 bearing 1800 engine. I suppose that knowing MG, it will probably virtually the same dizzy on both engines.
I had better get started with the degreasing and cleaning up then.
Colyn
Colyn Firth

Colyn,

not 100% sure, but you might have an issue with the rev counter if going from elecronic to points, but if it's just as get-you-home fix, then I suppose that wouldnt be too much of an issue.

Kind regards,

Grant :-)
G Hudson

Grant

He will be using a mechanical tacho with the 3-bearing 1800!

Steve
Steve Gyles

This thread was discussed on 24/03/2010

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