Motor won’t stay running

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Dana67Dart said:
Good thought. And good question.



OP says it will run for 30 seconds but maybe that's with the key in start?
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He said it runs for a few seconds and dies. Total run time is 30 seconds.

The coil is not overheating in a few seconds, it will run quite a while with 12 volts to it.


Now then I'm going with a vacuum leak. Look over the intake runners and make sure all vacuum ports are plugged.
 
moparhunter said:
( I haven’t timed it yet. )
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Well that's probably it then, not because the timing is wrong but because with too much timing, the throttle has to be closed to not have a high idle, and when you close the throttle, that shuts off or at least reduces the amount of Transfer-slot fuel dispensation.
My guess is that an extra turn of the curb-idle screw will get you in the ball-park. If the idle speed is too high, just retard the timing until she is happy.

If you take the carb off, reset the transfer slot exposure to between dead square and a lil taller than wide..... then leave it there! adjust Idle-speed with timing.
 
413 said:
The coil is not overheating in a few seconds, it will run quite a while with 12 volts to it
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I agree but if the coil is full volted for 5 minutes before the start attempts and the points are closed, maybe.


But I agree it is most likely a fuel delivery issue.
 
I have a few thoughts:
1. I am not trying to be rude, but when you completely rule out something, in this instance the carb, you can chase your tail forever looking for other problems only to eventually find that it is the carb. I have learned that the hard way! I am NOT saying it is the carb, I am just saying not to rule it out at this stage. It's like losing your keys and saying, "They couldn't possibly be in the garage, so I won't even look there. Then, two days later, you fine them in the garage. Oh yes, I remember now. My phone rang and I set my keys down so I could dig my phone out of my pocket!
2. You said the carb worked fine on another 400 big block 3 weeks ago. Perhaps something got jostled or tweaked between engines. Perhaps the idle adjustment for one engine isn't working well on the other. Perhaps a float is sticking. Who knows, but I would not rule out the carb yet. You've got several very knowledgeable guys suggesting that it could be the problem. Try this; crank the mechanical engine idle speed screw (the one on the linkage, not the idle mixture screws) in so that when the engine starts, it will run at way above an idle speed. That should help bypass the idle circuit.
3. Get someone to help you by dribbling some gas down the carb when it starts. If it keeps running then but not on it's own, I would lean towards carb, fuel pump or a partially clogged fuel filter.
4. It is not on an actual Engine run stand, so perhaps something is not hooked up properly? My friend Mark, the guy with the Studebaker Power Hawk, has an actual engine run stand. We have had several engines on it. It sounds to me like your setup is not working well for you if you can't even get it started and then shoot some gas down the cab before it dies.
5. Bad timing could be your culprit. That would be tops on my list.
6. A vacuum leak will ABSOLUTELY allow an engine to start and run but NOT idle. But that will be hard to check if you can't get the engine to stay running.
7. You might have to install the engine to figure this out. That way, everything can be hooked up properly, and you should be able to figure the problem out easier.
 
If the carb was run with E fuel.....
E fuel is hygroscopic, absorbs water. If the carb was left to sit for awhile, you would lilely get corrosion in the fuel bowls...& blocking the idle jets.
 
Stand there and spray carb cleaner in the air horn it while its running in squirts...if it stays running its the carb...or some sort of fuel delivery issue...sometimes troubleshooting is a simple as that...
 
Dartswinger70 said:
Stand there and spray carb cleaner in the air horn it while its running in squirts...if it stays running its the carb...or some sort of fuel delivery issue...sometimes troubleshooting is a simple as that...
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see post 5 then post 6, I guess its not that simple, but it is! (and yes I'm busting the chops of the OP)
 
Thanks to all the replies. I really do appreciate it. I haven’t had a chance to get back to the motor yet but will later on the week and will update my findings . Once again, thank you very much to everybody that is replied. I appreciate the support and advice .
 
I’m not gonna call this an update, but this is my thoughts as of now. I haven’t had a chance to get back to the motor because of the holidays but hopefully will next couple days.

When I put the engine together and I put the intake on, it was a brand new intake along with a new intake” pan “ I put it on dry as in no gaskets or silicone around the ports on either side of the tin. I’ve been doing some reading and taking the recommendations from here about it being a fuel/vacuum leak problem so I think I’m gonna pull the intake off and run a bead silicone around each port on both sides of the pan. Hopefully that’ll make the engine happy. I did not silicone it or use the gaskets because the gasket didn’t come with the pan. I haven’t worked on a big block in many many years but years ago I don’t remember ever using gaskets or sealant around the ports just the front and rear bars go . Anybody wanna chime in and share their thoughts on my thinking. Sorry for the long rant.

For the record, I am planning on using Permit tax ultra copper.
 
And if you supply extra fuel down the carb venture and the engine stays running longer you will know you have a vacuume leak.

You can also spray some starter fluid in the area you suspect a leak and if the ramp goes up you have your answer
 
[1] Do not use silicon that will be exposed to gasoline or gasoline fumes. The sil turns to jelly.
[2] The pressed bead in the bathtub gasket should, by itself, seal the intake/heads. If you want to use an extra 'gasket' Permatex #3 or #4 [ non-hardening & hardening ] would be good. A very old product but still works well.
[3] It makes no sense [ to me ] that this is a vacuum leak. Why would it run for a few seconds? Or run at all? I suspect carb/fuel related, post #31.
 
Bewy said:
Permatex #3 or #4 [ non-hardening & hardening ] would be good. A very old product but still works well.
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the #3 is aviation form-a-gasket and works great in applications such as this. it's PN 80019 (4oz bottle w/ brush cap). i'd recommend this over the copper spray.

you could also use p-tex #2 or hylomar

just none of that silly-cone near the gas.
 
413 said:
How do you have it wired up? How do you start it? Jumping starter or is a key switch and ballast resistor wired in?

A stock points mopar will do this wil a bad ballast resistor, starts fine and dies when you release the key.
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I agree, it sounds like the ballast is the issue. The reason I always keep an extra in the trunk.
 
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