engine issue

[Dawg66]

Hello,
I am kind of desperate here guys. I have a 66 charger with a 383 4 barrel . This engine was rebuilt and I am having problems getting it running smoothly. It has had all the wiring replaced as well. The car starts and will run fine with timing appearing to be correct.... set by a mechanic, and no sputtering or back fire. The car will run fine... then will sputter and maybe even backfire......not all the time. The TDC has been checked , firing order to cylinders....all wiring new. It is like, it is running great then it goes south any ideas would be helpful. I have replaced the distributor as well and then even put in a pertronix kit thinking that might help. I am just at whits end. Thank you for any new direction.

 

[HEMI-ITIS]

Check the timing curve and fuel level to start.

 

[66 Sat]

Coil breaking down when hot?

 

[Rockland71GTX]

Are you using fresh gas? Stay away from gas with methanol if possible too and use premium . What about the exhaust? Any chance critters built a nest in it while the engine was being rebuilt?

 

[Don Frelier]

Might be the fuel sending unit sock is getting plugged.
Try a temporary hose from the fuel pump inlet into a gas can.
Of course you can't drive it like that but see if that makes a difference.
Another item is the fuel pump pushrod length there has been a run of soft push rods that wear and get shorter.

 

[ddpsnake]

x2 on the coil

 

[Dawg66]

I appreciate the quick responses. It has new fuel tank and sender , and a new coil, timing has been checked and double checked, new plugs, even tried new wires, distributor , per tronix kit. This is why I am stumped......and of course no critters nesting. It will run fine then it can stutter and even backfire....like the timing is off. Vacuum advance also comes to mind but I know little about it. Everything is new, including all new wiring in car.....which is perfect. I was thinking carb now, but I am at a loss.....why it would run fine , then do this. BTW new Edelbrock , fuel pump. And No vacuum leaks.

 

[Don Frelier]

I would take the top off the carb and inspect for a fleck of rubber from a hose connection.
Blow that sucker out good.
Also new parts today does not necessarily mean they are good.
You just can't get anything good these days...

 

[91r/t]

I am with Don.....had a new coil from rev-n-nator and it took a crap in less than a year. Threw my old trusty coil on it from my Roadrunner which is an original Chrysler unit from the 70's and it runs fine now.

 

[theman440]

When is it sputtering? Accelerating from a stop, cruising, full throttle?

 

[Don Frelier]

I have an Accel super coil circa 1989 on my Charger.
My son said "its starting to look kinda crappy".
I said no way am I replacing that thing it works great I have confidence in it.

 

[Bad B-rad]

Not that this is 100% your issue, but I also have had a new out of the box MSD blaster coil, not function.

The fact that issue stayed present with the distributer changes, (did you install new cap, or use the same one) would point me toward fuel, like DON said.
Good luck!!

 

[Bad B-rad]

Thinking about it a bit more, how long will it stay running?
Are you driving the car when it happens, or just sitting in drive way?
Have you checked fuel bowl level?

Also when was it rebuilt, recently, or does she have some miles on it?
Just wondering if you may have a bad lobe in cam, due to lack of lube at start up, or no zinc in the oil.

Just tossing some ideas at you, I know how bad it can suck when an issue starts to drive you crazy!!!

 

[Dawg66]

New cap ,new coilx2, thinking same thing as you Brad..., new points and distributor then even converted to Pertronix... carb looked at too...even though it is new....will run great then and it happens when running and at idle in park....it is almost like a switch flips, and the timing appears screwed up .......therefore the back fire and rough running.....new vacuum advance canister as well.... but may have to look at it too, it is set at factory and on my second one too.......will check the fuel by bypassing tomorrow as I am off to work later on. I really appreciate all the input. I will follow up. It is ticking me off.....shouldn't be a bad lobe either or it would just be there. That is why I am so perplexed?????

 

[retroron]

I had something similar happen on my street rod. I had a high resistance ignition switch fault. When the switch got hot it would open and everything would turn to ****.

 

[Rockland71GTX]

What gets the condition to stop? Will it return to normal on its own or do you have to shut down and let it sit? Does it come and go or once it starts it stays that way? What is voltage at the coil? Is it lower when the sputtering starts? Try putting the timing light pickup on the coil lead to see if the spark is steady. What hasn't been changed? Fuel filter? As mentioned before hook up a temporary fuel supply straight to the carb. When the sputtering starts try giving it a spray of starting fluid to see if anything changes, that would point towards a fuel issue.

 

[coloradodave]

Yes, a worn cam lobe would not come and go... Check your distributor shaft for side clearance (shouldn't be any) and also check the reluctor to pick-up gap. The answers to the questions in post 16 above might help.

 

[Durandal25]

Coil , and more coil

 

[91r/t]

I have an Accel super coil circa 1989 on my Charger.
My son said "its starting to look kinda crappy".
I said no way am I replacing that thing it works great I have confidence in it.

I'd paint it and run it another 25 years!

 

[Dawg66]

Okay another update , then time for a nap, long night at work. I bypassed tank and ran separate gas line and it still happened. I have now pulled the carb....also pulled it partially apart and found a very small amount of dirt in each bowl....not a lot..BUT STILL. The only thing that was replaced last year was one gas filler pipe(horizontal) that was rusty, leading to the tank(problems getting in Canada at the time) . It likely had gas run through it once maybe since tank and sending unit were replaced the previous year; every piece is completely new now......I am figuring that is where the dirt came from. I rebuilt the entire car, so I do know it. That being said... I am thinking from look of plugs it was running a little rich as well. I will clean carb reassemble when I get up...if I have it in me.