HEI distributor GM vs DUI

Does anyone know if there/what are differences between the DUI distributor and a OEM GM distributor (other than the AMC gear, of course)?

The quality of the parts will be the difference. The module with probably be a china made part in the DUI and the weights in the DUI will be probably non-hardened. It's hard to beat the OEM parts. Whenever I have an opportunity, I always remove the China made modules and put an AC Delco part in instead. Besides, they generally last a lot longer than the offshore stuff. With the weights, DUI may use hardened weights but I'd definitely ask to make sure. The cheap distributors have soft metal so the weights end up getting worn on the pivot pins which oblongs the pivot holes and eventually hang up the advance mechanism. They also in turn wear the pivot pin rendering the distributor shaft useless. It's like everything these days,"It's pay now or pay later. Either way you'll be paying"........

I pulled two junkyard dizzies, replaced the gear (with the amc gear), and installed one as pulled. @ 8 deg btdc, I'm getting 8mpg (258 tbi) and no power, but runs good. Was wondering about advance differences. I'll rebuild the other and install it, probably the worn out antique parts causing me problems.

Your mileage depends on of the O2 sensor is working and how much timing you actually have driving down the road.

I bought and installed a D.U.I. in my 1978 CJ-7 back in 2005. I have had no problems with it at all. It probably has about 25,000 miles on it

i put a dui ignition in a cj7 that i had years back. i gapped the spark plugs way out and got great ignition with it. always idled great, and started right up. i added about 10 mph to my top speed with that bad boy.

Put a DUI in mine about 3 years ago. No problems. Only about 15,000 miles on it, but convinced it was the best thing I have ever put on it to date. Huge increases in performance, minor increase in mileage, but starts and runs much better.

jallan said:

I pulled two junkyard dizzies, replaced the gear (with the amc gear), and installed one as pulled. @ 8 deg btdc, I'm getting 8mpg (258 tbi) and no power, but runs good. Was wondering about advance differences. I'll rebuild the other and install it, probably the worn out antique parts causing me problems.

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Did you regap the plugs when you installed? Definitely want to do that to take advantage of the new stronger spark.

Other than finish, there is very little, if any, difference physically.

That said, this is one of those cases that I belive you do get what you pay for.
The DUI will come mapped to your specific engine/carb setup you have. The GM unit will not.
As for changing out parts on the DUI: DONT! Every part in it is comperable or better than the OEM GM part. The DUI is NOT a cheap Chinese disty. Its a high quality American Made performance part.

Be very wary of the CHEAP HEI units for sale, especially the ones online from China. They typically have Issues with tolerance and materials. They also come with incorrectly hardened gears that will wipe out your camshaft.

Currently I am running two GM HEI's and one DUI Dizzy right now.
No prblems with either, but the GM units are on GM/Buick engines and the DUI is on an AMC 304 V8.

Spark gap is .045 iirc, 8-10* BTC depending on the engine, the plug burn is great, power is smooth and they idle better than stock......Mileage is undetrmined, I am still dialing in the carbs as all three are running rich right now and not streetable. (too many Jeeps, too little time to work on them).

Love my HEI Dizzy's.
Hope that helps you some.

Gapped out the plugs to the max recommended limit. I had E3 plugs in it, thinking they would work best, but, as I expected when I installed them, they seemed cheap and easily broken/cracked. Switched back to the Split Fires and have had no problems. Them seem to be the best plug for the DUI. Trimmed the carb back to a lean mixture and it runs like a top (still).

Thanks everyone, made too many mods w/o putting a lot of miles on it between installs. And as Mark stated, too much to do and not enough time to work on Jeeps. I am currently getting a check engine light on my TBI (Howell) and need to diagnose it. Cranks/runs smooth, does not have the power it should....the tbi problem could be/is likely part of the problem. Plugs are gapped, running at timing at about 8deg btc.