Engine will not Idle.
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Senior User
Joined: Aug 2007
Posts: 167
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From: Ogden Utah
Engine will not Idle.
Hey all,
I searched through the forums for my symtoms but did not find any good answers. I am working on a 1976 F-250 4X4, 390 4 bbl. I helped my buddy swap from the stock 2bbl carb to a 4bbl. We installed a factory cast iron 4bbl Intake and a Edelbrock 1405 carb. The truck wont Idle worth crap. It seems to be flooding itself. I even tried an Edelbrock 1406 and it runs the same with 2 different carbs. There are no vacuum leaks. The timing has to be advanced by about 30 degrees to even come close to Idling and the engine lopes as if it has a very hot cam in it. I think it has a stock cam. We just installed a brand new Timing set in it also. I am baffled. Any help is greatly appreciated. Thanks.
I searched through the forums for my symtoms but did not find any good answers. I am working on a 1976 F-250 4X4, 390 4 bbl. I helped my buddy swap from the stock 2bbl carb to a 4bbl. We installed a factory cast iron 4bbl Intake and a Edelbrock 1405 carb. The truck wont Idle worth crap. It seems to be flooding itself. I even tried an Edelbrock 1406 and it runs the same with 2 different carbs. There are no vacuum leaks. The timing has to be advanced by about 30 degrees to even come close to Idling and the engine lopes as if it has a very hot cam in it. I think it has a stock cam. We just installed a brand new Timing set in it also. I am baffled. Any help is greatly appreciated. Thanks.
Senior User
Joined: Dec 2011
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From: Round Rock, TX
Sounds like a vac. leak. Have you sprayed carb cleaner all around the base of the intake and the carb? Did you set the floats in the carb? Did you line the dots up on the timing chain? Did you stab the dizzy with #1 at TDC on the compression stroke?
Last edited by 77393; Jan 27, 2012 at 07:13 PM. Reason: md
Thread Starter
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Senior User
Joined: Aug 2007
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From: Ogden Utah
I did spray carb cleaner all around the carb and intake and did not detect a vacuum leak. The truck is running the factory style mechanical fuel pump so I didn't think the fuel pressure would be an issue. How much fuel pressure does the factory mechanical pump push?
Thread Starter
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Senior User
Joined: Aug 2007
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From: Ogden Utah
Yes I lined up the dots on the timing set and the distributor is at #1 on compression stroke. I am thinking it is not a timing issue but more a carb or fuel delovery issue just not sure which. I have done this swap numerous times on different trucks and had no issues but for some reason this one is giving me fits. Thanks for the ideas and keep them coming.
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For one thing if the engine is stock to the truck it is a 360.
PCV hooked up?
Firing order correct? 1-5-4-2-6-3-7-8
#1 cylinder, front cylinder passenger side?
Absolutely sure you have the rotor pointing at #1 terminal (roughly 1 or 2 o'clock as looking down at it) at TDC compression stroke and not 180 degrees out?
Josh
PCV hooked up?
Firing order correct? 1-5-4-2-6-3-7-8
#1 cylinder, front cylinder passenger side?
Absolutely sure you have the rotor pointing at #1 terminal (roughly 1 or 2 o'clock as looking down at it) at TDC compression stroke and not 180 degrees out?
Josh
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Senior User
Joined: Aug 2007
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From: Ogden Utah
Engine is not stock. It is a 390. I am 100% positive the timing is set right. It is not 180° out. Firing order is right. Pa74f250 you have a good idea on the floats, I did not think to check the floats at all. I will check them tomorrow.
Fleet Mechanic
Joined: Nov 2010
Posts: 1,501
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From: Axtell, TX
Like Montana said, a fuel pressure regulator is pretty much required with an Edelbrock carb. They don't like more than 6psi. Since both carbs you tried did it, that would be my guess since you say you're sure you have the timing set right. But then if it was it wouldn't need 30° of advance at idle?
Senior User
Joined: Dec 2011
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From: Round Rock, TX
Just wierd two different carbs would act the exact same way. It really sounds like something in the timing is wrong since the only way to make it runs is by advancing it. Just to rule it out, I would bring #1 to tdc on compression stroke and check where the rotor is pointing. Did it backfire real bad, check the pin on the dizzy drive gear and make sure its not sheared. Keep us updated.
Senior User
Joined: Jan 2012
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From: Phoenix AZ.
I had the same problem with my 460 with a Carter carb. It turned up to be with my spacer not sealing it didn't have a vacuum leak around the carb because I sprayed carb cleaner but. It was pulling vacuum from under the center of the carb some how. I replaced the spacer and it ran great also mine smelled like gas which went away. Evedently the EGR spacer over time falls apart and leaks