Inline six Idle Problem

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Aug 3, 1999 | 05:11 AM

JazzBass

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Inline six Idle Problem

Hey guys!
This is my first time posting at this site. Great site! Anyway, I have a '81 F100 inline six with the single B carb (Holley, from Checkers) and I replaced it around 2.5 years ago and it seems that I have to replace it again. I think this because it came with a bad choke coil that would just let the truck idle fast.
Anyway, the problem that I'm having is that when I stop and a light or sign, the truck idles nicely for around 20 seconds then it start spittin and sputtering. Everyone that I've talked to said that I might have a vacuum leak. Well, I looked everywhere and I can't find one. One thing that I have noticed, 3 out of the 4 or 5 screws that hold the top and bottom of the carb together freely at the middle turn without tightening. Is this where my problem is at? The engine has 188,000 miles on it and I've checked the air filter and I changed it. No help.
If I do need an new carb, can you recommend the best place to go, ie..Autozone, Napa?
Thanks so much.
Your help is appreciated
JazzBass

Aug 3, 1999 | 07:39 AM

Phillip Guidry

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Inline six Idle Problem

The stripped screwa are definently part of the problem.If the idle mixture screw still has an affect on the engine when you turn it in or out,the carb is probably still good but you'll have to either put self-tapping machine screws a "hair" bigger or heli-coil inserts to fix the screw holes. You will have to change the gasket{s} in that joint which will require a carb kit so you may just opt for a reman. carb anyway to save time and labor. I can only recommend either TOMCO or HOLLEY for remans. While you are at it,do change the EGR spacer plate gasket! It is often overlooked but it is the plate that the carb sits on,with a gasket to seal it to the manifold.If this gasket is bad,it will allow exhaust gases to flow directly into the intake which will upset the fuel mixture causing a rough idle and sluggish off idle performance. Also remove the EGR valve itself for inspection and cleaning.The pintle should seal off the passage while resting.This will require another gasket also.
Phillip

Aug 3, 1999 | 08:25 AM

JazzBass

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Inline six Idle Problem

<center><font size="1" color="#ff0000">LAST EDITED ON Aug-03-99 AT 09:28 AM (EST)</font></center>

LAST EDITED ON Aug-03-99 AT 09:27 AM (EST)

Phillip,
Thanks so much for the info. Off the line, it's a real champion. No lag or anything, but I will change those gaskets. The idle mixure screw (I take it to be the only screw on the passenger side of the carb) does not really make that much of difference when turned. You mentioned "Also remove the EGR valve itself for inspection and cleaning.The pintle should seal off the passage while resting. This will require another gasket also. Is that plate that looks like a choke down where the carb or what does it look like.
So are we talking about a total of 2 or 3 gaskets
that I need to change if I went with a reman carb?
I know about the one that goes where the carb sets. The others I'm not quite clear on.
Thanks again Phillip. I appreciate much.
JazzBass

Aug 3, 1999 | 09:31 AM

Phillip Guidry

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Inline six Idle Problem

The EGR spacer plate is in between the carb and manifold. The EGR valve is mounted to the spacer plate. While you are at it tighten the intake/exhaust manifold bolts along side the head.

Hope this helps,
Phillip

Aug 3, 1999 | 09:37 AM

JazzBass

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Inline six Idle Problem

Phillip,
Thanks again for the info. I got it...Also, I failed to mention that I have a leaking Valve cover gasket. Can that also contribute to the rough idle?
Thanks again,
JazzBass

Aug 3, 1999 | 01:05 PM

Phillip Guidry

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Inline six Idle Problem

The leaking valve cover gasket reminded me to warn you about the PCV valve. If it is bad or the incorrect one,that could cause a rough idle. Get the correct one and check the hoses leading to it for cracking or clogging from sludge build up.Unless the valve cover gasket is dumping oil onto the dist. harness connections or the plug wires,I don't think it'll cause a rough idle.FORD coil wires seem to go out faster than vehicles also.
Phillip