What is the difference between DUI and the HEI dist?

[OEM1984CJ7]

I see the DUI sells for $300 and the HEI models you can get for $59-$99. What is the biggest difference and anyone have troubles with the HEI models? I have a rebuilt AMC 304 with new cam gear so wanting the one wire hookup.

Any suggestions?

thanks.

 

[BusaDave9]

HEI is the name GM came up with.
All those distributors you see from $59 to $300 are the same design as what GM made. As a matter of fact you can put GM parts into any of those distributors.
The real difference in quality is the gears. If the gears are mis-matched metals your distributor gear can wear out or worse yet is when the distributor gear wreaks the cam gear. Some people will remove the gear off their OEM distributor and swap it out with the aftermarket one but that doesn't always work out. Some aftermarket distributors have a different size shaft.

 

[Incommando]

Most of the GM-style HEI dists. for AMC have the correct shaft and gear. The problem comes on mixing a new dist. gear with a used cam gear. Either replace both gears at the same time or put the old gear off of your original dist. on the new HEI type dist. so that it mates with the original cam gear.

This dist. swap along with upgraded wires and opening your spark plug gap is a great upgrade for power, economy, ease of starting... I have used both the HEI and the TFI conversion that is so popular and the HEI is superior.

My personal belief is that you are only buying a name when you pay the extra for the Davis. I suspect that they call it DUI to be catchy and avoid royalties to GM because HEI is their property. The great thing is that you can get replacement parts anywhere for both...and the fact that the Davis uses the same off the shelf GM parts as the others is a big tip-off to me. Although Performance Distributors says they "assemble" and "tune" the distributors their web site stops well short of saying they "make" their distributors. To me that would be a huge selling point and the fact that they don't make that claim makes me wonder if they do not start with the same dist. as the cheapos???
www.performancedistributors.com

Here is a well-respected AMC engine authority's offering for $179.00:
http://www.bulltear.com/catalog/index.php?cPath=21_35
I am pretty sure that that is the popular $100 internet distributor and the fact that they are also vague about its origins kind supports that in my mind.

and the ultimate solution for those worried about the gears:
http://www.bulltear.com/catalog/product_info.php?cPath=21_35&products_id=33
I have just always re-used the old gears if there was no visible issues.

 

[justinfonder]

glad i searched for this thread before i started a new one. I had this exact same question as i'm looking to go HEI as well. Summit makes an HEI unit for $AMC 150 . in my eyes, summit is a pretty respectable brand, seeing how they are one of, if not thee, biggest parts distributors around. i've found a few others from unheard of companies. anyone have any bad experiences with these? i'm looking for a reason as to why anyone would spend twice the money for the DUI. if the gears are the issue, i feel like this would be an issue with the DUI as well.

 

[Old Dog]

I feel you get what you pay for most of the time. With that said I would avoid the cheap import dist. Anything under $AMC 150 probally isn't worth owing.

 

[xena1]

I found the Proform unit has too long a shaft and interferes with the P/S pump. I bought the Summit Brand (black cap) and it worked better. Ignition module crapped out because it wasn't coated with enough grease and overheated but it was standard GM item and not expensive. Other than that, unit worked out well.

 

[JR74CJ5]

All I can say is the DUI with a New set of MSD cam and distributor gears is so far working great for me, but too soon to be sure.

I chewed my cam gear up with either a combination of hardened dist. gear on a softer cam gear, or 3 positions of 2 different gears meshing and wearing out the cam gear slowly but completely...



DUI and MSD are typically considered the "better" brands, however as many have stated above, they are far from your ONLY option...

~ JR

 

[JR74CJ5]

and the ultimate solution for those worried about the gears:
Bulltear-Online
I have just always re-used the old gears if there was no visible issues.

I heard of a few of bull tears even failing, but would assume thats more user install etc? Though the accusations were they were still imported gears, though from how long ago those accusations were I couldn't tell you, nor weather they were "truthful"

 

[Rescue Diver]

I see the DUI sells for $300 and the HEI models you can get for $59-$99. What is the biggest difference and anyone have troubles with the HEI models? I have a rebuilt 304 with new cam gear so wanting the one wire hookup.

Any suggestions?

thanks.

I'm running the cheapest of the cheap HEI distributor. It was the $59 special, new from an ebay seller. Just like others have said, the factory GM parts including the 4 tab module will bolt right in.

I now have over 25,000 miles on it without a single problem. I'm running it in an inline 6, so the gear issues aren't really a factor like they are in an AMC V8.

Since you're running a AMC 304 , I would use a lot more caution where gears are concerned. Is your new cam gear a hardened one, or soft metal? If you don't know, I'd put just a few miles on it and pull the dizzy to look for signs of wear. I'd continue to do that every thousand miles or so for a while, as well as straining the old oil through a paint strainer to look for metal. I'd say if you make it through a couple of oil changes with no trouble, you should be good to go.

I'm a big proponent of the HEI because of its simplicity, but the gear issues with V8's are well documented, and setting it up with the right parts is crucial. Just because some company sells a new HEI for an AMC V8, it doesn't mean it has a soft gear, and the last thing you want is ground off metal running through your engine.

Good luck!

 

[justinfonder]

I now have over 25,000 miles on it without a single problem. I'm running it in an inline 6, so the gear issues aren't really a factor like they are in an AMC V8.

so the gear issue is not so with the AMC 258 i6 / 4.2l ? is this because the cam gear is already hardened in the AMC 258 i6 / 4.2l ? this is good to know as i'm about to do this swap. thanks

 

[Rescue Diver]

so the gear issue is not so with the 258? is this because the cam gear is already hardened in the 258? this is good to know as i'm about to do this swap. thanks

The cam gear on the inline 6 isn't an add on part like the V8. It's machined as part of the cam, so it's very hard steel. I can tell you for sure that I'm running the cheapest new HEI I could find in my 6 and I absolutely have no cam/distributor gear problems. I've heard from plently of others on here using an HEI in a AMC 258 i6 / 4.2l that also have no problems with theirs. There have however been a member or two that say they've heard of gear issues in the six, but I have yet to hear it first hand from someone that had gear failure in one, let alone what exact distributor they were running?

Just a theory, if some people have had problems with HEI gears in sixes, maybe they were running a factory GM HEI and they installed a reverse cut gear that they dug up somewhere that seemed to fit it, but it didn't match the cut perfectly, or the pin hole wasn't at the right height for the gears to mesh properly? Again, that's just a theory, because nobody with HEI gear issues of their own in a six has ever joined in on any of the many threads we've had going so we could learn from their experience.

I for one am MUCH more inclined to learn from those with direct experience than from those who read something somewhere that someone else wrote.

One piece of advice that I did find usefull with an HEI in a six is to make sure the distributor shaft isn't putting pressure on the oil pump drive shaft. Install the dizzy without a gasket to see if it's resting on the shaft or the block. If it has a little gap between the distributor housing and the block where the gasket would go, it's most likely sitting on the oil pump shaft. In that case, double up on gaskets so there's no bind before tightening down the keeper.

The only other issue you should have is the diameter of the distributor cap is a lot larger, so you'll need to clock it in such a way that the metal cap retainer closest to the block doesn't hit the block and interfere with setting the timing. That's easy to do.