Engine dies unexpectantly

[Mrbill426]

 

After over a dozen years our 'Cuda is finally back together and "derivable" again.  Hopefully there are just a few more things to do and it's done, for now, so we can enjoy it again.

Sorry, this is kinda long but...

I have an annoyance that I have not dug into yet but I am wondering if anyone has had a similar problem and found the culprit.  Yesterday after warming it up I drove it to a local car show just to get it out, and when leaving I got half way "up" my 300 ft of inclined driveway when the car ran out of pull and finally died.  I could have nursed the throttle in order to continue up but it is gravel and when it regained any pull it was spitting rocks so not an option.  I coasted it back down and then looked at the engine, and shift linkages etc over for any obvious problems and found nothing.

I started it back up and it ran rough for a bit but after burping the throttle a few time some it smoothed out.  Having found nothing obvious I went for it again with a bit more of a running start and it went all the way up the drive without a problem.  The 8 mile (non-highway) drive with stop lights were without incident.  I met up with some friends at a rendezvous point so shut it off for maybe 3 minutes... restarting was a bit of a chore but it did finally stay running and ran fine for the 1/2 mile trip to the show.  Back-up... when cold in the morning it fires up in seemingly less than one crank rotation.

After the all day (in 80-90 heat) show it started, idled, and ran fine; we stopped for dinner for and hour or so then I went home (again, it ran fine).  I pull into my driveway, stopped, and put it in park to check the mail box; the car is now angled downhill but not nearly as steep up by the road.  In less that 15 seconds while I'm out checking the box the engine sputters down and dies    I got it started but it ran lousy and as I feathered the throttle while coasting down to the house.  I let it sit for an hour or more then restarted it and put it in the shop...it ran fine once again.

Rebuilt .020"-over 340,  Edlebrock 750 carb, LD340 manifold, Lunati Voodo 262/268 cam, 9.50:1 measured compression ratio, stock Mopar electronic ignition, 727 automatic, 3.23 Sure Grip.   The carb I bought as gently used and put a gasket kit in it and put the original sized jets and metering rods back in as it had been altered. I carefully set the floats by the book; think is was 7/16"?

I suspect a fuel issue but I know zip about Edelbrocks or if they have "issues".  I may be a total coincidence but both times it has died were facing up or down hill.

Anyone have a similar issue, or can point me to a possible culprit?

Thanks!

[moreparts]

That does sound like a fuel issue, but I've had an electrical issue that was a lot like that too.  In my case it turned out to be a bad connection at the harness plugging in at the firewall.  Before you start chasing down the fuel I'd unplug the harness and make sure all the connectors are clean, tight, and making good contact.  You can check your wiring harness too if you think it's old enough to have any breaks or bad connections.

[Bullitt-]

  Would be extremely unlikely but I recall a member here that had a car that died occasionally when turning in a particular direction.... Problem turned out to be a bare wire dangling that only grounded out the ignition under certain circumstances.   

[Jay Bee]

I had a Mopar orange box go south on me decades ago. Car would run great when cold and all day long then for no reason just stall on hot days. Happened as a fluke, I thought, then started stalling out more frequently until the dealership finally found the problem. If you have a chrome or black one you're better off.

[Mixup7071]

I had a ignition coil when it got hot it would start cutting out and a side note it seem like the high performance ones would quit with in 6 months switch back to original equipment been on for years no problem

[Mrbill426]

Thanks, guys, I will be checking connections.
I do recall now that when I took it to have it aligned a couple weeks ago while sitting a a light it suddenly idled way down about 500rpm (on the factory tac) a couple times like it was going to die but then perked back up to  around 1000rpms.  I'm not sure how accurate that factory take is; it certainly does not match my old tac/dwell meter... it shows higher than the meter

[Brads70]

Has your ignition switch ever been replaced?

[Mrbill426]

@Jay Bee actually the module is an Echlin TP50.  Besides cam break in time the car has less than 40 miles on it. 

@Brads70 the switch is new; I replaced it and the signal switch when I went through the steering column.

I had a Mopar orange box go south on me decades ago. Car would run great when cold and all day long then for no reason just stall on hot days. Happened as a fluke, I thought, then started stalling out more frequently until the dealership finally found the problem. If you have a chrome or black one you're better off.

[bdschnei]

There's a speck of dirt or rust floating around in the carb primary fuel bowl. Ignition problems don't generally cause the issues you're having.

[tparker]

 

I was thinking the same. Something probably impeding the flow of fuel. I had something similar a long time ago.

[BIGSHCLUNK]

I had an issue on a Duster years ago very close to the described. Ignition box was the issue... once it got hot it needed a "cool down" period. Replced the box  - problem solved   

[Dakota]

I'm just thinking out loud here.... How comfortable are you that carb floats are set correctly and working correctly?   I don't have a lot of direct experience with carbs but the floats may be one components of the fuel system that could be sensitive to the incline/decline angle of the car.    It suggesting this to be the first thing you check, but maybe add it to the bottom of the "check this" list. 

[MoparLeo]

You start out " After over a dozen years..."
When was the fuel system replaced/gone over ? New tank, sending unit, fuel lines, fuel pump, carb "regasketed"?Fuel pressure checked ?
Next time it dies in a safe area, before trying to restart, pull the air cleaner and looking down the carb. Manually operate throttle and look to see if any fuel is squirting from the accelerator pump nozzles.
Electrical is generally off or on.

[Mrbill426]

@MoparLeo I probably should have left out the "dozen years" comment; that is simply how long the entire project has run.  New tank/sending unit, new lines, new mech pump, new inline fuel filter, regasketed and adjusted carb, rebuilt engine, etc. 

I have a list of things to check now including taking the carb off and (rechecking) the float adjustments, while inspecting the insides for foreign particles.  Going to remove the plugs and read them too.

Thanks 

You start out " After over a dozen years..."
When was the fuel system replaced/gone over ? New tank, sending unit, fuel lines, fuel pump, carb "regasketed"?Fuel pressure checked ?
Next time it dies in a safe area, before trying to restart, pull the air cleaner and looking down the carb. Manually operate throttle and look to see if any fuel is squirting from the accelerator pump nozzles.
Electrical is generally off or on.

[Mrbill426]

@Dakota yep I am going to check them over.

I'm just thinking out loud here.... How comfortable are you that carb floats are set correctly and working correctly?   I don't have a lot of direct experience with carbs but the floats may be one components of the fuel system that could be sensitive to the incline/decline angle of the car.    It suggesting this to be the first thing you check, but maybe add it to the bottom of the "check this" list.