DUI HEI weird advance
 

Helping a local guy with a Pontiac motor in a 81/78(81 car 78 nose tail) 5 speed.
New motor Kaufman D port top end Performer Crower HFT, DUI HEI.Holley Street Brawler carb, headers. Nicely done car.

Original distributor was doing strange stuff (I was not there) when he test fired it and ran it to break in cam, so got a DUI.

I have 3 in most of my Pontiacs and all work flawlessly. So putting the tining light on it is when it gets weird . It is an electronic light. Liked about 30 BTC at idle! DIU has 24 degrees in by 3000. Rev it it RETARDS for a second then goes back to where it was at idle! Consistently the same. Vacuum unhooked(It adds 10 degrees. Pulled cap off and advance weights not sticking and go the correct direction. He did put a whole new Painless wiring harness and the 12V wire he just has a spade connector and to me looks like a smaller gauge than factory wires. Not enough juice to module? It does not make sense to me it retarding then advancing but not any more than I had it at 800 rpm idle.

Carb having primary accel pump issues, takes a lot of throttle movement to get fuel out then it squirts. Lever moves with throttle. I adjusted the slack out of spring. It does it every time so not like it is building pressure. Thinking either check valve in bowl or under squirters for that.

I can figure carb out or even swap on one of my extras but the timing has me baffled!

Hope someone has some input. Sounds frustrating !

Going from fuzzy recollection I think the DUI system uses a touch more current than OE so wire gauge may be important... was the advance cam right side up for pontiac?

There has been a time where a holley carb squirter was lethargic with light and slower activation and I bent the bar that holds the check ball in place on the float bowl so it would activate a touch quicker, very slight bend ya can over do it

Skip I bet you have an issue like that other fella had the other day that had a post up.

I’d bet there’s an issue with a flaky Dyna Mod module.

Most will say it’s the timing light, but I’m gonna be honest about it, I’ve never seen that on my end. I’ve had the straight craftsman blink light they sold, and the same one with the dial back knob both. I will say the dial back craftsman was fine if turned to 0 and used as a straight blink light. No issues there for me. Now the thing was off a few degrees from what the knob said but it was off all the way up and down the same number.

I’ve seen most lights that get the pickup banged on the concrete when they get rolled up and stuck in/banged off the fan….well I can’t tell you about that they will all be off if you make a go it of that nonsense, but that’s not you.

95% sure you have a wacky Dyna Mod. I bet that West Coast Gto fella got the same thing going on. And if so … then perf Dist has an issue I warned em about a year ago…
The supplier of these modules is now and has been the under the same umbrella for about 2 years now.

And if that’s the case, the world has got problems coming they yet not realize is coming with these modules.

Short answer is call em and see if they’ll warranty it, I think they will. Ask for Brian. 901-396-5782.


Immediately short term, grab one from your favorite parts place(good luck and Godspeed), or better substitute in a good known used one for the short interim.

Let us know what happens…

What Formulas said plus look close to see if carb is sitting too close to intake manifold and squashing pump arm wasting travel motion…. Look at it, seen that before on small chevies.

While not the main issue the use of a lighter then required wire will reduce the needed available current as the firing rate ( rpm. ) goes up .

Ironically, I’ve seen that too on a small block Chevy. The pump was pressing against the heat shield below the carb. Made the pump delay squirting. It was surprising just a slightly thicker gasket fixed the problem.

Did you check for 12v to the dist? It’s possible the harness is wired for points and has a resistor wire for power? Maybe run a jumper wire straight from the battery. Also make sure the dist has a good path to ground.

I experienced what sun tuned explained. Some of these modules (I should say many lol) are whacky. They do weird things with the dwell time and affect timing.
I'd swap in a known good module and try again.

This is very interesting to me. I'm having some issues with my car as well - distributer and electrical is the issue (not the carb). My situation is inconsistency in timing/etc. With my 68 Lemans/455. I have the Americal Wire harness/fuel box kit. The wire (yellow) that goes from the engine fire wall bulk connection block I used a wire that is what I believe could be smaller that what it should be. Note: the 68 wire to the coil is a 2 wire set up. One wire to the coil is for start and the second wire (yellow) is for run. In this case my run wire is a smaller wire/Guage then I believe might be causing my issue.

Definitely put a voltmeter on that 12v feed wire and see what’s going on there, at key on, start, and while it’s idling.

Easy enough to pull coil cover and then you can get right at it without issue.

The original feed wire from GM was a strange deal. It was about between a 12 and a 14 gauge wire conductor with an over size large diameter of insulation. With using up to date modern type wire a 12 gauge wire is quite sufficient.

I’ve seen all kinds of goofy stuff done with the feed wire going to these HEI distributors on cars.

Too small gauge wire for sure won’t have the current carrying capacity it needs. Most HEis will only draw about 1.2-1.7 amps(Stock) the coils used in the DUI will only draw about 1-1.2 amps more than stock, so a total of 2-3 amps total at most.

My all time favorite deal to see on cars is where they pulled a points distributor and found a 12v keyed source to run the HEI that’s hot in the start AND run position and then run the distributor off that. At that point that’s a good deal…but then they pull the old carb and upgrade to one with an electric choke and then find theres not much places to find a choke power wire …so they T into the one powering the distributor.

I don’t like that.

Second favorite boo boo is where they try to power the choke off the positive side of a canister type ignition coil…
Yeah it’ll work, but not the most ideal situation at all.

With a smaller gauge wire used anywhere near where engine heat can soak into it that heat will raise the resistance of that length of wire and reduce the voltage level even more.

Also make sure your distributor hold down clamp is making a good ground connection to the distributor..
If I am running a painted clamp and distributor body I sand / scrape the paint off the contact point of the clamp and the lip of the distributor where they touch.

Don’t forget that the gasket under the distributor insulates it from electrical ground.

Another option is to make a separate ground wire to the distributor with a male and female spade used in it for a quick disconnect and lug rings to bolt it down at each end.

So to throw another wrinkle in talked to Lee on his engine stand -different distributor and different wiring motor did some similar weird stuff with timing ! I would think if balancer ring were moving it would not move back and that dramatic amount.

Cam thrust? would increased rpm move cam gear to retard it?

Getting a new pigtail for connection but something else is weird with engine.

Man just for giggles, try a different timing light just to see.

I posted last week regarding the new Proform dizzy that I just replaced in my 455 ( after the Davis unit took a crap 3 times with one coil and two modules). The Proform dizzy really likes 40 degrees at idle after warm up at the crank with vacuum disconnected. I choked it down to 30 degrees and the vacuum number off the carb went down to 12 inches. Car will run and start easily but you can feel it wants more advance.
I am going to pull off the bottom pulleys tomorrow and verify that the new SFI damper is not spun at the keyway. Other than that, it is time for a dyno to lock down what is wrong.

To clarify, I had this engine on my test stand a little over a month ago. The owner of the engine lives near another friend of mine, and that friend put us in touch. The owner built the motor himself. We ran it on the test stand to break in the cam and check for leaks and such.

I've got plenty of voltage and larger than needed wiring. I've got a dial-back timing light that I've used on other motors. After break-in, we set the total timing to ~36 with the engine @3000-3200rpm. Upon idling it down, the timing was higher than expected. "Hmmm, maybe the distributor moved" I thought, and brought it down around 14. When I revved the motor with the timing light on, the timing RETARDED!

I checked the weights, and they seemed correct and moved freely. I tried a different rotor, thinking that maybe it was binding - not the issue. My conclusion was that SOMETHING was screwy with the distributor, which was a new Summit house brand. I set his float levels, and the car was running decently. I tagged Skip in a video I took, of the motor running on my stand - smooth and proper throttle response.

Owner took the motor home, and ordered the DUI. Once he had it in the car, he first had issues with the carb - turned out he had a kinked return line and carb was over-pressuring. He got THAT fixed, and now he is at the problems described by Skip.
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I've seen that scenario multiple times, all when the timing chain is off one-tooth.

He is running a larger hot wire tday as the Painless did look a little small.

I had to swap in one of my RobbMac starters as the ProTorque was eating up the gear on the new flywheel to even crank it.

He is going to check voltage after he runs the larger wire. Also got a correct tach/Bat plug for it.

Weird two distributors, two timing lights doing weird stuff! He said he did put the cam thrust plate on it when he installed and degreed the cam so not like a SBC with a roller and no thrust button. It ran smooth once we got more advance in it with the new distributor.
I'll keep you all posted as what we find out.

I figure a balancer outer ring slipping would not be oscillating back and forth the exactly same amount!

David lives my side of town and about 5 miles from my shop. His whole street has a bunch of car guys . One with a blue Cobra kit car-I saw cruising the curvy roads near the shop this afternoon. Paul that Lee knows has a 62 and a 75 Vette and a gold "Rockford" TV show Firebird maybe a 76-that also cruises the curvy roads. And when you are on those roads 10 crotch rockets will scream past you going about 90 MPH!

DUI had not ideas. Said a bad module usually runs bad. Said could cheek ohms between green and white wire. Should be 90 ohms.

90,Ohms and steady with a little wire wiggle to check for a near break in wire..

One time I cobbled together a system using a old Hays electronic ignition mag. coil/pick up to a Crane HI6 box, I started it up and timing would retard with RPM swapped wires from mag. pick up and then it acted right .... but with so many distributors being used in this case it would appear that it's something else that is present during all observations

I'll pull the old orignal(and still old!) points distributor out of my 65 GTO and see what it does:)

Skip if they said check ohms between green and white pickup coil wires…. I’m quite sure they meant 900 ohms.

Myself I cut em back to anything between 760 -850 and they better be steady cold and hot.

You might try one last thing… remove the pickup coil leads from module and twist them together 2-3 turns. A twisted pair. Will help alleviate stray EMI but it not a fix all all the time.

They’ll fix it if you send it back or I’m sure I can. Lemme look sometime.

Thanks. Yea I did see the extra 0 now that you mention it at 900!

So Bob, when you re-build a 4 pin HEI distributor for a customer, that needs a new module, what do you use???

I remember a couple of years ago you were helping a friend with a crate engine install in a 56Chevy?

Seems like the engine wouldn't run right, you found the 4 pin module to be at fault. you tried modules from different part stores, but none performed properly... I'm not sure you mentioned the solution to this???
THanks
Jeff:confused2

Jeff,
That was a few years ago. Good memory!

That was a brand new GM crate 350. I had bought modules from autozone(Wells), Oreilleys (Standard), and Napa (Echlin). All were sub par.all suffered same symptoms.
It wasn’t until about 3 weeks later that I found out why.
Standard had apparently bought everybody else out and as I was told we’re operating under the same umbrella of buying power.

Well it don’t take a finance major to figure that one out. They gonna use the lowest bid.


In the year and a half that followed, I watched about 8 bought for customers cars and with 0 exceptions all 8 were returned . That was enough for me on the 4 I bought one Saturday previously to figure that deal out.

So I went and bought 12 Dyna Mods from Perf. Dist. I think I got 1 left. When I get back over there I’ll likely do it again. If I have an issue, I can get it resolved without any hassle.
So far I’ve not had any. Now a couple guys at work recently have used the modules Oreilleys sell (Standard) with no issue yet. So maybe they’ve identified that problem and corrected it. Not sure.

I’ll just put it this way. I’ve got a stash of about 6 GM modules from 1995 the ones made in Singapore, those I got put back for stuff I own. Those will do me fine. And I swear to you guys, I won’t mess with stuff too long, I’ll yank it if it’s problematic and I will put a worked cast iron single or dual point distributor right where that HEI was sitting in a heartbeat and not lose one second of sleep over it or about it.

I remember back in the early 90’s when everyone was talking about em coming for our cars… nah, but it’s hard to drive it if you don’t have parts. Parts is where it’s gonna get ya. And sorry quality parts will put the worst taste I. Your mouth you ever had.

We’ve had several customers at work come in and want the new fuel injection some other shops have installed a couple years ago took off the car and regular old stuff that actually works put back in its place. I love that! It’s a sad waste though, but you can’t argue with the result. I mean I hate they paid all that $$ for what’ originally was supposed to be a better mousetrap, but it rarely works out that way. I mean if you’re gonna let gas go stale it’s gonna wreck the internals of a carb, but guess what? It’s gonna do same to EFI also….

I don’t know what the problem is exactly on these modules, or really if there actually is one here in the original post, but I’m sure it’ll shake itself out eventually. And when and if we do we just have to figure out a plan B.

He got the squirter system flushed and new hot wire measures 12.7 so will try and see what the timing is doing this weekend.

New hot wire larger gauge and a correct pigtail got it pretty normal, different timing light did the trick also. Not sure what the deal was with original distributor and Lee's hook up but seems to advance "normal" now.

Well done Skip!!

Thank you for the update. Glad it was something simple.

Me too!