70 Duster runs rough or dies when up to operating temps

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70DUSTER/74SCAMP

Sold the scamp ....still got the duster tho
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So short story......slant 6 70 duster to 318 swap...all new components carb electrical ect......when i start the car cold runs decent idles great ....go drive it down the road drives good . try and back up or turn around wants to stumble. drive home runs good. park in the drive way idles rough spits and sputters and dies. while at idle my coil gets 7.22 Volts.. the ballast resistor ( pass side) has 12.70 Volts, the driver side of the ballast is 7.05 Volts...... 600 rpm idle edelbrock 600 cfm, electric pump with 6.8 lbs of pressure.....battery volts at idle is 13.34 volts. alternator at idle is 14.15 volts ...... TIMING is at 9 degrees BTDC . i feel like when the engine gets up to op temp it wants to act up.....not sure if i got the wires switched on the ballast resistor or not. Hooked them up the way the factory slant 6 wires was, besides i added the wire to orange box for 12 v feed. i feel like when running the coil should have near batt voltage....maybe not enough hot spark for the fuel , im at a loss . new orange box module new coil , plugs wires, cap rotor, distributor alternator , battery .. obviously frustrated and need help. thank you all

zach
 
Also is there a difference between a slant 6 ballast resistor and a v8 one? im running a oem replacement 2 prong resistor......
 
you have 7 volts to the coil, I would say you got the ballast wired correctly. I have seen that at higher RPM the voltage to the coil increases but I'm not sure it ever reaches 12V

  1. Your 12V source to the orange box comes from the correct cir? 12 V in Run / Start not after the ballast resister?
  2. Orange box is well grounded?
  3. Do you have another to swap in to see if that is the issue?
  4. The reluctor gap is correct?
  5. the carb is adjusted correctly?
  6. the choke is opening when at temp?
  7. there have been reports of distributer wires from the pickup being reversed and making a difference ( I still don't know how that works) but you could get 2 trailer light pigtails and make a polarity switched connector
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OR it might be as simple as you need to tune it to idle when hot rather than cold. Choke will take care of that for you.
 
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Too much fuel pressure for an ede carb. Turn it down to 5-5.5 max

Initial timing may be a little low. I run pretty much everything at a minimum of 12-14 degrees BTDC. Requires limiting mechanical in distributor most of the time.
 
Edel/Carter AFB/AVS carbs will run comfortably with 8.5 psi of fuel pressure.
Why a specific FP might be specified is because it changes the fuel level; so float level setting may have to be adjusted to suit FP. My experience with these carbs is that they are not overly sensitive to FP or slight differences in float level settings, so I doubt this is causing the problem.
Also, not pick up wires reversed. That causes a drastic change in timing & misfires. Since it starts, runs & idles great, this cannot be the problem.
Since the problem only seems to occur once up to operating temp, I would check for the choke sticking on or the blade loose. It could also be electrical, something failing when hot. These ign systems do NOT supply a full 12v to the coil in run mode, nor will they work with a coil that is designed to use a full 12v [ no bal res ]; your measurements look OK for coil voltage, but the bal res HAS to match the coil. The Mopar ECU uses a 0.5 ohm bal res for the coil. If the coil was designed for, say, a 0.8 ohm BR, then it will getting more current than designed..& getting hotter.
 
What trans, auto or manual? What converter?
What camshaft hydraulic or solid? Stock or lumpy.
What is the idle vacuum?
Do you have any vacuum leaks?
does the accelerator pump work normal?


Idle at 600 RPM, is this in gear or park?

Start with raise idle speed, advance timing, lower fuel pressure.
 
Try checking the reluctor gap in the distributor...
 
Stock 904 transmission with a aftermarket stahl convertor i thing 2500 i was told, bm shift kit. with z gate shifter. hydraulic camp , lumpy one. stock internals. aluminimum eddy intake and a 1405 carb. choke is actally pinned back but when warm at 70 out or higher i wouldnt think it would run rough. i am going to try and back fuel pressure down , raise timing a hair and back idle down. also check the reluctor gap . it idles at 750 when in park around 600 in gear. Getting ready to head out and see what we can come up with i will let u guys know. i took the day off to work on it lol.....and possibly have some busch lights lol
 
You don’t want idle any lower than 600, raise it to 700. It won’t bang into gear with that converter. But you don’t want to carb open too far at idle, so go a little bit higher.

check the idle vacuum and set the mixture screws for highest vacuum on the gauge.

choke wired open is fine/good.
 
Sounds like its leaking or driven in partial choke mode. Have you ever tuned from when its rough idling and dying? Or do you just set it in choke and drive off?

Try 4 turns out on the idle screws.
Try a little wd40 or water on spray bottle around the carb base to check for a vac leak as well. Do you have the flat adapter plate under the carb or this one not need it? I prefer holleys..so my memory isnt crisp on the plate requirement.
 
Edel/Carter AFB/AVS carbs will run comfortably with 8.5 psi of fuel pressure.

My experience and many others here, Ede's don't like excessive fuel pressure. Run more than 5.5 and it pushes past the needles in many cases. Ede instruction say no more than 6.5 for the 1403-1413 carbs

It take little time to adjust and see if the car runs better at a reduced pressure.

Good luck to the OP getting it fixed up.
 
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Stock 904 transmission with a aftermarket stahl convertor i thing 2500 i was told, bm shift kit. with z gate shifter. hydraulic camp , lumpy one. stock internals. aluminimum eddy intake and a 1405 carb. choke is actally pinned back but when warm at 70 out or higher i wouldnt think it would run rough. i am going to try and back fuel pressure down , raise timing a hair and back idle down. also check the reluctor gap . it idles at 750 when in park around 600 in gear. Getting ready to head out and see what we can come up with i will let u guys know. i took the day off to work on it lol.....and possibly have some busch lights lol
A 150 RPM drop going into gear is too much. Likely your initial timing is too low. You want to aim to only have the engine drop 50-75 RPM when going into gear. What kind of distributor are you running? Stock Mopar, MSD, etc.? You will likely need to check the timing curve as well. Lots of performance/economy can be had from fine tuning the curve.
 
@70DUSTER/74SCAMP

Do you have the cam grind that is in the engine? That would help a lot. Also what type of vacuum is it pulling at idle of about 750-800, lumpy cam set it to 800-850 and see what happens. I'd set the idle there and tune it a bit for close to highest vac reading. Lots of suggestions how to set via vac reading by searching the board.

You know where the timing is now. Try this if it's easy to do. Flip the wires coming out of distributor. If the timing retards, put them back to original position.
If it advances timing, wires were hooked up backwards to start with. Reset timing and move on knowing it is now wired correctly.
 
I fought the same issue (warm up and dies in 10 to 20 minutes) in my 340. Although you said that you have a new coil, my coil bench tested (ohms) okay. Swapped coils and car ran fine. Evidently when the coil heated up something went wrong in it. I would suggest trying a different coil.
Yote
 
Ok i just had to gap my reluctor to .08 it was pretty far gapped from factory. its a oem replacement on from oreilys. timing was 9 BTDC so i advanced it to around 13.... set idle around 800 in park. i also backed my fuel pressure down a bit hovering between 5 and 6.... the coil is a stock napa oem. i do have a msd blaster two laying around may have some life left in it i could try but i still have my new oem ballast resistor. can i run those together? i just let it warm up for 10 mins drove it down the road about 2 miles came back , ran good no stumble nothing. came home and let it idle it ran for 7 mins then fumbled and dies. this is the vacuum i just checked at idle . scratching my head here. i do have a spare old school crome mopar ignition box i could swap out and see if that helps. if it works lol......idk im scratching my damn head . on busch light one may need more lol......thanks for all the help so far like i said i know enough to get my self in trouble if that makes any sense . if anyone is up for a chat via the phone later dm ur number lol.

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Ok i just had to gap my reluctor to .08 it was pretty far gapped from factory. its a oem replacement on from oreilys. timing was 9 BTDC so i advanced it to around 13.... set idle around 800 in park. i also backed my fuel pressure down a bit hovering between 5 and 6.... the coil is a stock napa oem. i do have a msd blaster two laying around may have some life left in it i could try but i still have my new oem ballast resistor. can i run those together? i just let it warm up for 10 mins drove it down the road about 2 miles came back , ran good no stumble nothing. came home and let it idle it ran for 7 mins then fumbled and dies. this is the vacuum i just checked at idle . scratching my head here. i do have a spare old school crome mopar ignition box i could swap out and see if that helps. if it works lol......idk im scratching my damn head . on busch light one may need more lol......thanks for all the help so far like i said i know enough to get my self in trouble if that makes any sense . if anyone is up for a chat via the phone later dm ur number lol.

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Sure sounds like something is getting hot and failing. Your idle vacuum is high, which is good. You must not have a very lopey cam. My 360 engine had a Blaster 2 with a stock ballast resistor and worked fine. I would try the Blaster coil to see if that makes any difference. As RRR has said many times, new (parts) does not always mean good.
 
lumpy one.
If that vacuum is at 800 rpm in Park then may WAG is thats a cam with around 270 adv duration.
Crackedback is giving you good advice. You have nothing to lose and all to gain by backing the fuel pressure down to 5.5 psi or less.
With winter fuel and hot temperatures, its that much more likely to be getting high fuel levels in the bowl. 4 psi is plenty to keep the bowls filled driving around and in idle. I don't know that's the problem but again nothing to lose and all to gain.

The fact it runs good cold suggests the idle mix may be rich or the fuel levels were high. However there seems to be some inconsistancy in that so don't see that as a clear cause - effect.

Establishing fuel level is one of the first things to do. That's why I covered it first.

Close to first is establishing timing. However you have some wiring questions and those take precedent.
The ballast resistor itself is non-directional. It will .5 to .7 ohms whether the current flows left to right or right to left. With the electronic ECU resistance should closer to 0.5 ohms. So far not seeing this as the issue but make sure resistance is in this range as many aftermarket ones peple are reporting as over an ohm.

The 16 gage blue or blue with stripe wire is power supply with key in run. It should be very close to the same voltage as the power source.
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while at idle my coil gets 7.22 Volts.. the ballast resistor ( pass side) has 12.70 Volts, the driver side of the ballast is 7.05 Volts......
battery volts at idle is 13.34 volts. alternator at idle is 14.15 volts
As Dana wrote, having lower voltage on the coil side of the resistor when the engine is running is correct.
HOWEVER, you found 12.7 V at feed side of the resistor while the alternator is producing 14.1 Volts. That's a problem.
Additionally, you found the battery was only seeing 13.3 Volts when the alternator was producing at 14.1 V - also a problem.
Those two measurements indicate
1. resistance between the alternator output and the battery.
2. resistance between the main splice and the ballast resistor.
Next time note the current on the ammeter when measuring these voltages. That will further clarify where the problems are as well as the severity.

electric pump with 6.8 lbs of pressure
Depending on how the pump is wired in, and the type of pump, this could be making the problems worse.

Now timing
TIMING is at 9 degrees BTDC
If that's at 700 rpm that would be plenty for a stock 318, but your cam is not stock.

timing was 9 BTDC so i advanced it to around 13.... set idle around 800 in park.
When measuring at 800 rpm with a parts store distributor, its likely that the advance has begun. Take some timing measurements at higher and lower rpm if at all possible. Its possible, and common, to set timing at 800 rpm or more, then when the transmission is in gear and the engine rpm goes down, timing goes down. I don't think this is the cause of the rough running you're experiencing but important to be aware of when setting 'iniital'. Whether stock or hot rodded, knowing the rpm of the timing measurement is important.
 
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I'm with Bewy, post #5 and offer this;

Your 150 rpm drop may be caused by; Not enough throttle-valve opening, caused by too much timing.
The proof is in the mixture screws being out too far and black sparkplugs.
The stalling could be because of sooted up plugs, or a too high or unstable fuel level.
The 15" of vacuum could be a bit of a cam, but without hearing it, it just as easily be a stock cam and a vacuum leak, or more likely a flooding condition..

I would begin by setting the Transferslot exposure under the closed throttle to a bit taller than wide, and closing the mixture screws to 3.0 turns. After this, do not readjust the speed screw!
Then reset the idlespeed using timing, to 550/600 in gear. I'm assuming you have a good working PCV system, no vacuum leaks and the coolant temp is around 185. Do not pay attention to the actual timing number just now, just make it idle as above.

A flooding condition is easy to diagnose, now; just pinch the fuel line right closed while the engine is nearing a stall, trans in Park. If the rpm starts to recover, there you go, the fuel is going too rich. Let it idle until the rpm peaks. then shut it off. Pull the top off. Whatever the fuel level is in there now, record it. It will be a lil lean for day to day driving but it will be close. And it will be your target WET fuel level. So make a float adjustment towards a lower level and repeat the test. When you get it synced up, time for another road test.
But first; reset your idle-speed to 550/600 in gear by using timing. And then fiddle the mixture screws for smoothest idle , between 2.5 to 3.5 turns. If it wants more than 3.5 turns, she is lean so give her a half a turn more on the SPEED SCREW, and twiddle the mixture screws again between 2.5 to 3.5 turns. If she wants less than 2.5 turns, she is fat so subtract transfer fuel by decreasing the speed screw by .5 turn. Depending on how many changes you made, the idle speed should not have changed much, but if it did, well, put it back to 550/600 in gear.
Now it's roadtest time.
Pay attention to freedom from; a tip-in hesitation, to response to gentle accelerations, to the rpm or speed they occur at, cuz we will have to fix that later. NO WOT bursts yet. Then take it home and see if it stalls again.......gotta fix this first. If it does it again, my money is on a leaky float valve, so you'll have to pop the top and compare the current WET level to your previously recorded numbers. If they differ by much, you have a choice to make, but first go look for debris in the valves. If none found, the choice is to reduce the fuel-pressure or to replace the valves. If the pressure is already below 4.5psi, just buy new valves. But before you do, if you have brass floats, make sure they do not contain fuel; take'em out and shake them. If they do, you have another choice; fix them or replace them.

Happy HotRodding
 
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It is not a fuel pressure problem. The Edel fuel system is an EXACT copy of the original Carter AFB fuel system & Carter recommended 7.5-8.5 psi for performance applications. The Carter float level chart goes to 10 psi. I have personally run 11 psi, zero problems. The float leverage system on Carter/Edel carbs is well designed for high leverage on the float needle BEFORE flooding would occur. Further, the Edel carbs use the smaller 0.093" n/seats, where some AFBs used larger 0.101" n/seats. The smaller the n/s seat, the more pressure it can take before fuel pressure overcomes it. If somebody would like a copy of the 10 psi chart, pm me an email address.
For the umpteenth time, Edel specifies a 5.5 psi pressure because that sets up the fuel level for their 7/16" float level as a datum point for the correct a/f ratio with the jets that the carb is built with. It is NOT the max pressure that can be used.
The Max Wedge & Street hemis used Carter AFBs, exactly the same float system as the Edel carbs & they came with 6-8 psi pump ratings.

Run the engine again at idle with the timing light hooked up to the coil lead so you can watch the flash. When it starts to fumble, see if the flash rate changes; this might be hard to see but could give a clue if the problem is spark loss.
 
I read through this pretty carefully and I think I found your problem
"on busch light"

I had similar situation on a car I just bought. I swapped the coil and ECU and I'm good now. Plus no Busch light
 
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