DUI problems?
Thread Starter
Instructor
Joined: Jan 2015
Posts: 101
Likes: 2
From: Rochester NY
DUI problems?
I just installed a new DUI distributor on my 355 crate engine and have problems a ready. I started the car and it was clearly not firing on all cylinders. I took out the plugs - cleaned them off and the car ran fine. I switched the car off, restarted it and the same happened again. This time on investigation the plugs were wet.
So
I replaced the plugs - took it for a drive and things again were fine. The next day - again - it is chugging away on less than all cylinders. And so the story goes on - each time I start the car on a different day it is neccesary to clean the plugs first or it will not be firing properly. I will typically get 20miles before I need to take remedial action.
The car is garaged and not driven too hard. It has a new crate engine with new plugs,wires,carb and manifold.
I know that I am not special and hope that it is a standard problem that someone with more mechanical knowhow than me can help with?
Any and all greatly appreciated
So
I replaced the plugs - took it for a drive and things again were fine. The next day - again - it is chugging away on less than all cylinders. And so the story goes on - each time I start the car on a different day it is neccesary to clean the plugs first or it will not be firing properly. I will typically get 20miles before I need to take remedial action.
The car is garaged and not driven too hard. It has a new crate engine with new plugs,wires,carb and manifold.
I know that I am not special and hope that it is a standard problem that someone with more mechanical knowhow than me can help with?
Any and all greatly appreciated
2026 Loser of the Year
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From: New Or-leens Loo-z-anna
I did a search of DUI: Suggestions were to add a second 10 ga. ground cable (to the head from the battery negative post). They also said to add a 12 ga. wire from the battery negative post to the distributor housing.
Thread Starter
Instructor
Joined: Jan 2015
Posts: 101
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From: Rochester NY
Thanks for the quick response. I was thinking it was a ground issue as well. Any idea how to add a wire to the housing?
Le Mans Master
Joined: May 2003
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
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To me- it sounds way too random to be a bad ground....The distributor doesn't pull that much current to warrant extra grounds. I mean if your car's starter turns fine- then I doubt another-bigger ground would make a difference.
Sounds to me like a bad module- or just another case of Chinese junk. Do you have another distributor to drop in and verify it is the DUI.
Richard
Sounds to me like a bad module- or just another case of Chinese junk. Do you have another distributor to drop in and verify it is the DUI.
Richard
Race Director
Joined: Jul 2015
Posts: 13,082
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From: SW Florida.
Actually that dist is grounded pretty good bolted to the engine. And the starter works so the engine ground can handle several hundred amps. I buy 50 buck Chinese Large cap HEI distributors for my boats and they run great.
Le Mans Master
Joined: May 2008
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2022 C3 of the Year Finalist - Modified
I installed a DUI distributor in my car when I restored it, timed it, and its run perfect ever since. No additional grounding, nothing. And DUI is MADE IN USA. Call them, when I bought mine, I ordered direct from them, and they seemed very friendly.
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Drifting
Joined: Mar 2011
Posts: 1,347
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From: Kernersville NC
Same experience here. Looking at their website they recommend that any paint on the intake as well as the hold down be free of paint at contact points. If you can confirm metal to metal contact points I would suggest calling Davis. You could have a bad module.
Thread Starter
Instructor
Joined: Jan 2015
Posts: 101
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From: Rochester NY
I put a 12 gauge ground wire on the hold clip because it is a new manifold and it still didnt work. I put my multi meter to the hot wire and it drops when i start it to 9. It has a new battery but i think i ran it down. Im going to recharge and see what that does. Plus when i was trying to start it some of the exhausts were hot and some cold which tells me that not all cylinders are firing. Right?
Last edited by Japery; Aug 9, 2018 at 07:50 PM.
Instructor
Joined: Apr 2011
Posts: 161
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From: NW CT
What year is your corvette? Was it points originally? If so did you you bypass the resistance circuit?
If you didn't then that could be causing your 9volts and misfiring. You need a good solid power source for the HEI.
For testing you can run a jumper wire to the BATT terminal on the HEI to something like the B+ on the alternator or even in to the plus side of the battery. Unhook the wire that is connected there now so you don't backfeed in to the harness. Remember the car wont shut off until you unhook the jumper wire.
http://www.superchevy.com/how-to/130...an-hei-system/
If you didn't then that could be causing your 9volts and misfiring. You need a good solid power source for the HEI.
For testing you can run a jumper wire to the BATT terminal on the HEI to something like the B+ on the alternator or even in to the plus side of the battery. Unhook the wire that is connected there now so you don't backfeed in to the harness. Remember the car wont shut off until you unhook the jumper wire.
http://www.superchevy.com/how-to/130...an-hei-system/
2026 Loser of the Year
Joined: Sep 2013
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From: New Or-leens Loo-z-anna
Post your results. More experienced members can narrow down the problem from your results.
Thread Starter
Instructor
Joined: Jan 2015
Posts: 101
Likes: 2
From: Rochester NY
The car is a 77 and it did come with a 94 Iroc engine with TPI. I couldn't get the thing tuned thou. I charged the battery and seems to work OK but thats what happend the last time. Fingers crossed,
Thread Starter
Instructor
Joined: Jan 2015
Posts: 101
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From: Rochester NY
Instructor
Joined: Apr 2011
Posts: 161
Likes: 17
From: NW CT
Next time it acts up measure the voltage at the BAT terminal on the HEI then measure the voltage right at the battery. If its drastically different then you have a wiring issue. If your 9volts on the battery then you got something up with your charging system.
Le Mans Master
Joined: Mar 2004
Posts: 7,493
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From: Little Rock AR
I vote for a bad coil. Mine was acting up intermittently after I replaced the coil with an aftermarket unit. Put the original GM coil back in and all is well.
Try another known good coil.
Try another known good coil.
Drifting
Joined: Apr 2014
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From: montague michigan
C2 of Year Finalist (stock) 2019
What year is your corvette? Was it points originally? If so did you you bypass the resistance circuit?
If you didn't then that could be causing your 9volts and misfiring. You need a good solid power source for the HEI.
For testing you can run a jumper wire to the BATT terminal on the HEI to something like the B+ on the alternator or even in to the plus side of the battery. Unhook the wire that is connected there now so you don't backfeed in to the harness. Remember the car wont shut off until you unhook the jumper wire.
http://www.superchevy.com/how-to/130...an-hei-system/
If you didn't then that could be causing your 9volts and misfiring. You need a good solid power source for the HEI.
For testing you can run a jumper wire to the BATT terminal on the HEI to something like the B+ on the alternator or even in to the plus side of the battery. Unhook the wire that is connected there now so you don't backfeed in to the harness. Remember the car wont shut off until you unhook the jumper wire.
http://www.superchevy.com/how-to/130...an-hei-system/