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Chevy ignition module mod

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The matchbox ignition module went out on my 720 pickup, none to be found at the wrecker, dealer price sky high, so I adapted a Chevy TP45SB 4 pin module to the stock distributor and coil.


The surprise is the engine (L20-b head on Z24 block) runs MUCH better than when I had the matchbox module on it!

Nicer idle and easily revs past 4500 rpm (it used to bog at 4500)

Cheap module at $20 and common item at any auto parts store. :)

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  • 4 years later...

Does anyone know if this mod would work on my 1980 L20B in my 720? I'd really like to try it. Mine is barely running now and I don't want to spring for the price of the matchbox module if I can avoid it.

Thanks for any advice anyone can offer.


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Hello everyone,

I'm wondering if anyone can tell me how to replace my matchbox with the Chevy module. I've got a 1980 720 with the L20B that has only four plugs and the matchbox dizzie. After hearing about this mod I did an image search for the HEI module and I see several variations on the number of prongs that they have. I see one that has only two prongs. Would that work?

Would love it if it increased the spark a little bit - especially if it saved money over buying a replacement matchbox.



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This mod is only for replacing a very expensive matchbox ($320 at Nissan) that is broken or missing. There is zero gain from this, only savings of +$300. The HEI unit is simply an electronic switch turning the coil on and off. If your matchbox is working leave it.... this is like changing a tire that's not flat.


If you have the older style remote igniter style this is also a cheap alternative.

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I would like to try this mod for practical reasons. I'm not sure my matchbox works. the truck has multiple problems. One of them is that it feels like it's losing sparking intermittently. I'm thinking if I can try a different module cheaply it might be a good way to figure out if my module is bad. Does anyone know how to wire it up to take the place of a matchbox?

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It seems that the JNC.com link to the writeup is gone & or not working but theres plenty of info in this thread. Ill add that on my 620 ive now mounted the HEI to a bracket thats attached to the coil bracket & is grounded that way. Its "floating" so to speak & not screwed onto the inner fender support.

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