440 six pack not running issues

[Jimmyspeed59]

Hi I’m Jim and I am just finishing a 1970 challenger restoration and the motor is giving me a fit. The motor runs very rich but idles fine. Has idle vacuum of 16 inches. The six pack is brand new when purchased from Jegs 6 years ago took me that long to finish this project. When motor was built it was dyno tuned making 408 hp and 506 torque a very mild build basically stock. Now when the motor is in the car it fuel fouls the plugs black but drives ok but after it warms up after 5 minutes of driving it wants to start misfiring and eventually just quits. Now here’s the strange part. I can disconnect the ballast resistor and run a jumper wire to send 12 volts to the coil and it will crank right back up and run fine. Also if it runs for a extended period of time at idle in the shop it will do the same thing. The ignition was converted to a brand new mopar electronic ignition system, the orange ECU, new ballast, coil etc. and this is the same set up that it was dyno with so it worked fine. All the wiring in the car is new and checked voltage at coil when in start 12 volts and run 8.1 volts. The fuel does seem to be boiling though because fuel will continue to slightly come out the center carb squirters even when the engine is off. I even lowered the fuel bowl level in the center carb to just below sight plug hole in center carb to help with this but no luck. The base timing is 14 degrees with 34 total seems to run best there and good vacuum. The engine temp is around 190 no overheating. I desperately need help with this because I would hate to scrap this six pack set up and put on fuel injection. Spent a ton of money as it is. I just want this thing to run

 

[rklein71]

Simple things first. Make sure your ECU is well grounded to the body and run a good ground from the engine to the body. Electronic ignition is real sensitive to a lack of ground. Since it is a new restoration, you will need to scrape off paint around the grounding points. A weak spark can cause a plethora of carb problems.

 

[rklein71]

By the way, your car looks amazing.

 

[Jimmyspeed59]

Thanks on the compliment on the car but yes I did grind the paint off before mounting the ECU and voltage regulator also ran a 4 gauge extra ground from back of block to the body also verified with a meter. But thanks

 

[aussiemark]

I agree awesome looking restoration, I always thought ballast resistors were only used on points type ignition systems and to run full 12v to electronic ignitions?

 

[Jimmyspeed59]

I have the 2 prong resistor that sends 12volt to the coil when you turn the key to start because it bypasses the resistor but when you release the key then it goes through the resistor to the coil and the voltage is around 8 volts. But 12 volts go to the ECU continuously. The earlier 5 pin ECU that actually used 5 pins needed the 4 prong resistor because they operated at a reduced voltage. The 5 pin orange boxes you get today doesn’t use the fifth pin it’s just a non connected wire. Basically the 4 prong resistor is 2 ballast resistors in one. One for the coil and one for the ECU only to be used with older “real” 5 pin ECU. It just seems like my car runs much better with the resistor bypassed because it creates a much hotter spark from the secondary winding of the coil but I don’t want to overheat and burn up my coil. There has to be a better way.

 

[rklein71]

Maybe try a different ballast resistor and control box to try to eliminate the cause. I like to try eliminate the simple things first when diagnosing before getting to the hard things.

 

[Jimmyspeed59]

Well I did try my old resistor that was in this car originally with the 318 points type motor and that resistor gave me about 1.5 volts more at the coil. The car idled faster and smoother I guess from the hotter spark from the coil but as the car warmed up the voltage started dropping and eventually would die. Just took a little longer. My thing is this engine ran once with this equipment when we ran the cam in and done dyno pulls. I don’t want to have to keep a dozen boxes and resistors in the car just to be able to drive it. I can’t imagine all these mopars are like this. All my wiring harnesses are new from year one except for my factory power window harness. I do have a MSD 6 box and a big accel coil I could mount on the firewall and scrap the factory stuff but would hate to do that. Take away the factory look of the car. Is there a better alternative than that orange mopar box? I did here they were unreliable.

 

[dadeo1852]

You sure it's the squirters that are dripping after shut off and not the boosters. The squirters are part of the accelerator pump circuit and would not be affected by fuel bowl level.

 

[rklein71]

I have seen where an HEI unit is put inside the orange box, the ballast resistor has a bypass wire behind it, which maintains the stock look.

 

[Jimmyspeed59]

I have seen where an HEI unit is put inside the orange box, the ballast resistor has a bypass wire behind it, which maintains the stock look.

 

[Jimmyspeed59]

Yes I’ve seen that done too. I think I might try my MSD box six I got a brand new one laying around in the shop left over from a previous project.

 

[rklein71]

I wouldn't blame the six pack. I ran one for 25 years. This sounds entirely ignition related. These parts can work great for a short time and start messing up without any rhyme or reason, even when brand new. I have had brand new ignition parts go belly up shortly after purchase.

 

[Jimmyspeed59]

You sure it's the squirters that are dripping after shut off and not the boosters. The squirters are part of the accelerator pump circuit and would not be affected by fuel bowl level.

Yes it’s definitely the squirters or aka accelerator nozzles. It was just barely dripping out after the engine was off.

 

[Jimmyspeed59]

I wouldn't blame the six pack. I ran one for 25 years. This sounds entirely ignition related. These parts can work great for a short time and start messing up without any rhyme or reason, even when brand new. I have had brand new ignition parts go belly up shortly after purchase.

I know electronic parts aren’t what they used to be but I just want something dependable.

 

[Jimmyspeed59]

Yes it’s definitely the squirters or aka accelerator nozzles. It was just barely dripping out after the engine was off.

I have a video of it but I can’t get it to upload on this sight.

 

[rklein71]

I did have problems with my six pack at the end before I sold the car in that the alcohol in today's gas doesn't go well with rubber and messed up the needle and seat assemblies. I bought rebuild kits from Dayton that are ethanol friendly and that cleared up the issues I was having, running rough and not idling as well as it used to.

 

[Jimmyspeed59]

I only use non ethanol 93 octane fuel. That’s all we can get without buying race gas somewhere. Although the shop that built the motor and dyno it I’m sure probably used race gas or a blend of it. Maybe I need to start mixing race gas with my 93 octane to bring it up some. I’ve also pulled my carbs off a half dozen times checking needle seat, jets,gaskets,etc. I wish I had just put on the 4 barrel now or fuel injection but I was going for the WOW factor. Ol well hind sight. Thanks for the reply I’ll keep plugging at it.

 

[rklein71]

Don't be afraid of the six pack, sounds like you know your way around a four barrel and they are really no different. Make sure your linkages fully close the outboards when the center carb is shut. The outboard carbs have air fuel mixture screws under lead plugs at the front of each base plate. If your center carb can kill the engine either direction with the air fuel mixture screws, then you probably do not have to mess with the outboard air fuel mixture screws. I think I had to unscrew my outboards about a turn and a half and never messed with them again. To me, it sounds like your issues are electrical.

 

[Jimmyspeed59]

Don't be afraid of the six pack, sounds like you know your way around a four barrel and they are really no different. Make sure your linkages fully close the outboards when the center carb is shut. The outboard carbs have air fuel mixture screws under lead plugs at the front of each base plate. If your center carb can kill the engine either direction with the air fuel mixture screws, then you probably do not have to mess with the outboard air fuel mixture screws. I think I had to unscrew my outboards about a turn and a half and never messed with them again. To me, it sounds like your issues are electrical.

Yep pulled carbs off several times and tried 3/4 turn on outboards then 1/2and now 1/2turn but still has strong gas smell. The transfer slot on center carb is the traditional small square below the throttle blades. I think your right about the electrical though I think I’m just not getting enough spark to burn the fuel properly. Thinking about trying this MSD box I have and finding some stock champion plugs instead of these auto lites the engine builder used already cleaned them 3 times anyway from being fuel fouled. I have been working on this thing for months I have never run into this kind of problem tuning a car. I won’t give up though got to get this car finished I have another project I want to build.