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I'm shopping for a new distributor for my car, I'd prefer to stick with an HEI for simplicity.
This will be for street performance, seeing 6,000 RPM on occasion, in various built small blocks.
At one time the Chevy Performance 19432312 was recommended, it seems to have doubled in price over the last few years (I knew I should have bought one when I bought my car).
Is it worth the price if there are less costly units out there? Will it be more durable (last longer) and have better parts availability?
I've looked at D.U.I. mostly due to reputation and a lower cost than the Chevy unit, then I read that they use a proprietary module.
I want something with off the shelf parts availability.
I see Summit has their own model.
The Accel unit was recommended a few years ago on here, has the quality dropped since Covid?
Would I get a better product if I went with something other than an HEI distributor?
I have a DUI HEI. It takes regular modules or any OE brand that fits. You can change modules, caps, rotor, or coil if you want. I have an MSD module in mine. Has been reliable 15+ years, and was custom curved when I bought it.
Everything at GM costs lots more than before; little else doesn't.
Both Brand New 4-pin HEI's from either GM or DUI are very good and top quality.
Several years ago, GM began sourcing from IIRC Taiwan (that was printed on cartons). But they do have a pretty good performance curve. Very good Quality.
Davis' is equally good, with option to have them custom curve to your stated needs.
JME: only those two New 4-pin HEI are essentially equivalent.
If IF you have the chops, rebuilding & recurving a greasy old used GM 4-pin HEI will yield results just as good.
No doubt, there are dozens of relatively unknown auto electric shops; that can & do this work for you.
Also, not a thing wrong with a good points & condenser dist. Many hi-dollar points dist can be had for a song; primarily because of sheer ignorance. Virtually all of those are all-USA.
Of course, there are many guys who claim great results with a 50-dollar chinesium piece (until it turns fugly).
Last edited by Rebelyell; Apr 10, 2026 at 05:10 PM.
I have a DUI HEI. It takes regular modules or any OE brand that fits. You can change modules, caps, rotor, or coil if you want. I have an MSD module in mine. Has been reliable 15+ years, and was custom curved when I bought it.
The MSD module is the best. I did go with the MSD Ultra box this time. The old 6ALbox
can be swapped in place for a quick diagnosis if needed.
DUI all the way. All HEI distributors use a proprietary module. The DUI module will go straight into a GM distributor and vice versa.
I had DUI custom curve a distributor for my engine in my car.
Then send it overseas. No it wasn't the cheapest distributor.
I am extremely happy. No external boxes or complex wiring.
Most any add-on CD ignition boxes (as above) e.g. MSD, Accel, Mallory, Fast, Crane etc.
CD boxes typically replace only the HEI's module (which is essentially an inductance amplifier); replaced with a higher-voltage capacitive discharge amplifier.
Ignition System still requires a distributor, cap, rotor, coil & trigger (all of which are self-contained in a 4-pin HEI).
* terminology "4-pin" In earliest iteration of GM HEI, refers to quantity of electric terminals on GM ignition module. More-recent models have more pins which assist in ancillary functions. Most performance HEI ignition modules have but 4 pins.
** To date: OE serial production ignitions with CD are Very rare. Rare because OEM's REQUIRE substantially robust long-term reliability. OEM's have the resources & have done the reliability & probability studies. The purported reward of CDI, hasn't squared with CDI's probable risks; not on large-scale production.
The distributor that is on it is an unknown as to it's history.
It has a Napa module and the timing jumps around some.
I also like to have spare parts on hand, particularly electronics.
Originally Posted by peters220
I suggest that you investigate the reason for the timing moving around. JP
Agree, find why timing jumps.
If dist is a genuine GM 4-pin HEI, repair & freshen it with best quality parts. Standard Ignition aka SMP makes very good parts (do Not buy the "budget" series with "T" suffix). If this dist uses 4-pin module, Seek out & acquire NOS "990" aka 1875990 ign module (beware counterfeits). Ensure that heat transfer paste as Required to be between bottom of module and dist housing hasn't dried up & disappeared (it does); renew that w/ genuine heat transfer paste (same as used to mount PC cpu).
A common source of timing jumping around is a failed harmonic balancer aka damper. The rubber bonding outer inertia ring (where the TDC timing groove is) to the inner hub fails, and outer ring slips along with its groove. When ring is slipping, its groove will be seen with timing light to be moving about. This is quite common, given the car's age; it has fifty years of heat & oil degrading damper's rubber. If ring's slipping, Do Replace damper asap.
Last edited by Rebelyell; Apr 11, 2026 at 03:12 AM.
Plastic Cam timing gear teeth flying off can do that. Worn out distributor advance mechanism will do that too.
If you need to replace the worn out advance mechanism, you can buy a NOS GM replacement shaft assembly. It comes with all the moving parts for the centrifugal advance, plus a new GM rotor. You just pop the gear off, slide the old shaft assembly out, slide the new one in, and add the distributor shims as required while you are at it and reinstal the gear. The ZZ4 shaft assembly or many L-48 shafts have curves with a desirable length, but might benefit from a spring swap if you want it to come in faster. ZZ4 curve is about perfect for what I build. Pick out a new vacuum advance can from the Lars list and drop it in.
Last edited by stingr69; Apr 11, 2026 at 07:55 AM.
Fresh rebuilt engine, new damper, timing set and cam.
I used the carb (Quadrajet off a '76 CA Camaro w. auto) and distributor off the old engine.
I'm getting the timing nailed down before looking into the carb.
I have Lars's papers and Cliff's book, this carb has been set back to factory spec and tuned to the best of my ability.
I'll seek help with it if it indicates it needs it.
Freshly rebuilt C3 engine indicates New flat tappet cam + New flat tappets (lifters).
If new flat tappet cam + lifters did Not break-in as intended; that certainly can lead to flattened lobes + wrecked lifters.
And a distinct miss.
Sadly, failed flat tappet cams/lifters have become all-too common. Often those failures occur during attempted break-in.
Root cause(s) run the gamut. Regardless, it's a real thing.
To help rule in Or rule out flattened lobe(s), suggest measure lobe lift on All sixteen lobes and compare to new cam's specs.
The car ran great, better than it did with the old distributor, until it quit.
Got it towed home, verified no spark, swapped in the old distributor and it fired right up.
That was on a Sat., so on Sun. I was texting with Summit returns, they got a new one shipped out, I think I had it by Tues.
The second one one lasted 120 miles, this time it quit after a 20 mile drive, half a block from home.
I was carrying my spare distributor and tools, so I swapped it out and limped it home (I was too frustrated to mess with the timing, I made it run well enough to limp it half a block).
Summit says two failures is rare, they have very few failures on the DUI distributors.
They suggested I contact DUI. If I get no help there I'll swap the module out and see what it does.
This car ran for 1600 miles with the old distributor while under my ownership.
Two new ones fail?
I have 14.22 V @ idle @ the distributor, 14.17V @ 4000 RPM, both with no load.
New upgraded GM alternator (I forget the amperage, it was sufficient for the electric fans I installed).
I can't think of anything on the car that would cause the module to fail.
Very unusual they make a good product
I don't run a module I run a MSD 6 AL. Not a problem. Contact the manufacturer there is probably something wired wrong
I put a DUI in my 77 a couple years ago now. Best thing I ever did for my engine. Excellent quality. Had them custom curve one for my car. Works fantastic.
Really makes me wonder about your double failure.
If the old one hadn't run for so long I'd suspect something on the car was causing the failure.
I'll see what they say tomorrow but I'd like to reinstall the DUI and, if it's still dead, swap the module from the old one that runs.
I wonder if it's heat related, we set records for high temps here today.
Last week I was out for a much longer drive but it was a cooler.
Who Builds A Quality HEI Anymore?
