400 dies after releasing gas

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Old March 18th, 2014 | 09:41 AM
  #1  
Joffroi's Avatar
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From: Ballwin, MO
400 dies after releasing gas

I just got a 68 442 with the original 400. When I test drove it, it ran great and idled great. Got it delivered yesterday and it starts up just fine and sounds very strong. However, as soon as I release the gas the engine shuts off. The previous owner said they recently got the carburetor rebuilt.

Any opinions on what you think the problem is? Bad fuel filter? Choke need adjustment?

Thanks
Old March 18th, 2014 | 09:44 AM
  #2  
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Could be choke coming off too soon.... among a lot of other things.
Old March 18th, 2014 | 09:45 AM
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Did you try adjusting the idle screw?
Old March 18th, 2014 | 09:51 AM
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Originally Posted by 70cutty
Did you try adjusting the idle screw?
Unfortunately, I haven't had time to adjust anything really yet. Since the car ran great when I last drove it, I didn't know if something like the idle screw would still be considered as a potential problem area.
Old March 18th, 2014 | 10:07 AM
  #5  
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Choke pulloff opening too far perhaps
Idle adjust and choke operation are the obvious first steps.

Is it factory divorced choke? Cobbled choke?

What happened in the past is irrelevant.
Old March 18th, 2014 | 10:13 AM
  #6  
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Likely a lean condition. Look down the carb with engine off, choke off, warm engine. Actuate the accelerator. Do you see 2 strong shots of fuel from the squirters? If not its the carb... If yes then look for vacuum leaks. Brake booster, vac advance, all hoses, throttle plate, manifold to carb gasket. Hook a vacuum gauge to the manifold (not to the carb) to get a baseline then start searching. But first adjust the carb to obtain the highest vac reading possible. Once you've dialed in the carb set the timing and dwell to obtain the highest vac reading. Then go back-n-forth from carb to timing to obtain the highest reading. Depending on the cam you should idle somewhere about 18-22" of vac at curb idle which I think is 6-700rpm depending on trans and A/C (engine warm choke all the way off).
Post results.
Old March 18th, 2014 | 10:59 AM
  #7  
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I would inspect the tune up parts and specs and make sure all that is serviceable and correct first. Open the gas cap and see if the tank smells like varnish if the car had been sitting for any length of time before you got it.
Old March 18th, 2014 | 01:11 PM
  #8  
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Sounds like a vacuum leak. The PCV valve is an often overlooked idle killer! If the vehicle has been sitting for a while it can get sticky and cause a HUGE vacuum leak that you cannot hear outside the engine.
Old March 19th, 2014 | 02:14 AM
  #9  
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Does it do it cold? hot?Not sure on 68 dashpot still there?possible lean issue.yes do check the fuel as oldcutlass stated.Nick
Old March 19th, 2014 | 03:40 AM
  #10  
MDchanic's Avatar
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Since it's unsafe to drive until you replace the frame, I say don't worry about it now.
The engine is coming out anyway, and who knows what problems will have popped up, and what things will have been fixed, by the next time you can drive it.

- Eric
Old March 19th, 2014 | 09:08 AM
  #11  
Joffroi's Avatar
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This morning I had a very small window of time to poke around. The gas smelt like gas. I definitely saw 2 strong shots of fuel from the squirters when the accelerator pump was initiated. The PCV connections were as stiff as can be. I move it around a bit not really thinking there was anything I can do at the time. Before leaving for work I cranked up the engine for fun and low and behold it idled great. I could put it in park, drive, reverse, and let off the gas with no issues.

Do I need to just replace the PCV connections?

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Old March 19th, 2014 | 09:19 AM
  #12  
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Looks like the PO put an Hei dist on it.
Old March 19th, 2014 | 08:06 PM
  #13  
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You've got to go through there, check all the belts and hoses, check the fuel filter, check the vacuum advance diaphragm, check the PCV, check the power brake booster, check the function of the heating vacuum system, replace the wires, probably the plugs, and maybe the cap and rotor, and just generally do a full tune-up.

And all that for a car that you don't intend to drive for a long time because of the frame's condition.

- Eric
Old March 19th, 2014 | 09:31 PM
  #14  
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I would replace all the hoses and do a major tune up and adjust. Was it at a different elevation than you are at? That can effect things. Hard rubber lines can have cracks you don't see that can cause leaks. Play it safe and replace them all. I had a very nice 68 that someone did an HEI changeover on and just poked a hole in the firewall and did not use a grommet for the wire going threw. It caused a fire. Take the time to look over everything. I change oil and filter and coolant on all cars I get that are drivers. Just play it safe.
Old March 21st, 2014 | 07:23 PM
  #15  
Joffroi's Avatar
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I had a little time to mess around with the car tonight. The engine started dying again in idle. I went straight to the choke and immediately noticed a difference depending on how much I had it opened. I didn't have time to actually adjust it but I'll put that on my "to-do" list.
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