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MGB 1974 MGB distributor drive dog- which one is it?

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wkilleffer

wkilleffer

Jedi Knight
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Which drive dog does the distributor on an 18GK engine use equipped with a 25D4 distributor? I'm thinking about ordering a new Ignitor-equipped dizzy which requires an A-series drive dog. I'm assuming that part has not been changed on my car.

Thank you,
 
I believe all the A- and B-series engines used the same profile Lucas dizzy and dizzy drive dog up until the introduction of the A+ series engines. Sorry, I don't know the part number for the dog. If your engine is currently running the 25D4, you will be able to install an A-series dizzy if you want to.
 
Ok, I was looking at a distributor on the retro rockets site that was made for BMC A and B series engines. The company responded to my email and said it was made out of a Lucas 45D4 distributor, with a Pertronix Ignitor pre-installed. It would cure alot of what ails my current setup.

Thank you,
 
Your original dog will work with it.
 
Re: 1974 MGB distributor drive dog- which one is i

Yup. It's nearly a "one size fits all" with MGB engines.
 
Re: 1974 MGB distributor drive dog- which one is i

So, how do I put the original dog on the new dizzy? Will the worn shaft bushing cause a problem there as well? Or will the new dizzy just drop right in to the hole that the old one comes out of?

Thanks,
 
Re: 1974 MGB distributor drive dog- which one is i

Nevermind that last question. I think I've got it figured out.

Thank you,
 
Re: 1974 MGB distributor drive dog- which one is i

Does Pertronix actually sell the 45D4 with no dog on it?

If it's an honest-to-God Lucas part that they've rebuilt the shaft will be pre-drilled for the dowel pin that secures the dog to the dizzy shaft. If the new dizzy comes with no dog, press the pin out of your old dizzy so you can remove its dog. Move the old dog along with any shim washers between it an the dizzy housing, and press the pin back in to secure it.

Any place you could install a 25D4 you can install a 45D4. The top half is different due to changes in the advance weight system, the part that goes in the block is the same size. If you wanted... you could even put an old DM2 dizzy in the MGB block. They didn't change for decades. The 45D4 will fit right in your MGB block.
 
Re: 1974 MGB distributor drive dog- which one is i

I went ahead and ordered the new distributor and one of their coils. We'll see what happens and hope for the best.
 
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