77 F150 idle issues

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Oct 8, 2011 | 01:14 AM

Ferrariferg

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From: Tacoma

77 F150 idle issues

I recently bought my dads 77 F150 Custom w/351M 2v carb, and it has a problem idling when its cold. The engine and carb are both rebuilt and have maybe 1000 miles on them since. When its cold it will not idle on its own. As long as you hold the gas it will stay running. Once its up to operating temp. it seems to idle fine. It takes about 15 minutes for it to get up to temp. I know that carbs can be cold blooded, but this is ridiculous. My dad and I have both adjusted everything on the carb (including the choke) 10 ways to Sunday, but it makes no difference. Anybody have any ideas? I want to use this truck as my daily driver in a couple weeks, so I need to get it working right. Any help is greatly appreciated.

Oct 8, 2011 | 08:08 AM

rdweathers

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From: Florida

Sounds like the choke needs to be adjusted so that the butter fly is open a little more. To djust this, locate the black circle on passenger side of carb, loosen three screws around this cap and turn cap counterclockwise a notch at a time. Sound be an index mark on topside of black cap and index marks on top of carb where the two come together to use as reference. There is also an idle adjustement screw on this same side of carb for choke that may need to be screwed in to speed the idle up while choke is in operation. This is accessed from back of carb, below black cap and in the area of throttle shaft. You should be able to tune these to operate almost like a modern day vehicle. I have three carb vehicles with no cold start related problems. Within this forum is an article on how to adjust the choke with pictures and step by step instructions. I am not sure where to locate it.

Oct 8, 2011 | 08:16 AM

fmc400

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From: Austin, TX

It sounds like you've adjusted the choke, but the fast idle speed and fast idle index are just as important. You can have the choke adjusted properly, yet the engine still won't idle properly while cold because the fast idle is not properly set up. This is part of what RD is describing.

Give this post a read: https://www.ford-trucks.com/forums/7...ml#post6422219

Oct 8, 2011 | 12:26 PM

Ferrariferg

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From: Tacoma

Thanks guys. That really helps a lot. I'll give this a shot next weekend when I'm at my dads.

Oct 16, 2011 | 12:31 AM

Ferrariferg

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From: Tacoma

Thanks for the help guys. I did all the adjustments today and now it runs great. Only issue now is that the idle drops to about 400 when you come to a stop. Gonna adjust the idle and mixture screws tomorrow. I also installed a small sunpro tach. Sure is nice to know what the engine is revving to.

Oct 16, 2011 | 10:07 AM

fmc400

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From: Austin, TX

Glad to hear you got it worked out. A vacuum gauge is great for dialing in the idle mixture.

Oct 16, 2011 | 11:21 AM

montana_highboy

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From: Big Sky Country

Quote:

Originally Posted by fmc400

A vacuum gauge is great for dialing in the idle mixture.

Concur, it's also the one gauge that will give you more info on overall engine health than any other gauge on your dash, if you know how to read it correctly, to me it's just as important, if not more so, than your oil gauge.