New Carb High Speed Idle Issues
Thread Starter
|
Freshman User
Joined: Mar 2015
Posts: 48
Likes: 0
From: Windsor, California
New Carb High Speed Idle Issues
Ok .... Got a nice remanufactured Holley 4180c carb and installed it in my '83 F250 4x4. Took it for a drive today and found an odd issue. With truck fully warmed up and choke visually verified in the off position ...While driving, when I let off the throttle to take a corner or to stop at a stop sign it is at the high idle until I tap the throttle to bring it back down to curb idle speed. This is a real issue when driving because the throttle is not closing all the way when I let off the gas peddle and I am accelerating when I want to be slowing down. Any ideas what the issue could be? When I look at the carb with the engine warmed up I can see the choke cam is disengaged and the choke plate is at 90deg just like its supposed to be .... so it doesn't seem like the choke is mysteriously re-engaging once I drive down the road. But something is not letting the throttle plates close all the way without a quick snap of the throttle.
HELP
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
Check the throttle linkage. Also what type of gasket do you have under the carb? If you have a thick squishy gasket it can cause the carb throttle shaft to bind and be sticky.
Go out and rev the engine by hand and let it down gently. If it's fast idling, go ahead and take your hand and pull the throttle closed. If this slows it down I would investigate the throttle binding somewhere.
Go out and rev the engine by hand and let it down gently. If it's fast idling, go ahead and take your hand and pull the throttle closed. If this slows it down I would investigate the throttle binding somewhere.
Thread Starter
|
Freshman User
Joined: Mar 2015
Posts: 48
Likes: 0
From: Windsor, California
I've got a thin gasket under it so its likely not the gasket. Also, I cannot duplicate the problem without driving it (putting a load on the engine). With the hood up and engine running I can run the throttle back and forth slowly, fast, whatever but the problem doesn't occur. Only happens when I get in and drive .... confusing the h*ll out of me at the moment ... Checked throttle linkage also and all is well there. ? ? ?
Thread Starter
|
Freshman User
Joined: Mar 2015
Posts: 48
Likes: 0
From: Windsor, California
Gonna pull the carb and investigate things tomorrow. Internet research has given me more 'ideas' than actual help. Could this be caused by secondary throttle plates not being closed enough to properly cover the transfer slot? Just one of the 'ideas' I read .... any help from everyone here would be GREATLY appreciated .... this a new (remanufactored) carb so I am seriously confused
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
The secondaries do contribute to the idle, and some of the carbs have idle screws in the back of the carb. But tapping the throttle should not help it if they are sticking open, the throttle is not connected to them, they are only operated by the secondary diaphragm. If you could never get the idle down low enough, then yes I would look to the secondaries.
Why don't you warm it up. mark the the round black choke adjustment with a mark so you can put it back, and then loosen and turn the adjustment so the choke has a lot of pressure on it to keep it open. Then try it. Just to make sure your choke is not borderline on the adjustment.
Why don't you warm it up. mark the the round black choke adjustment with a mark so you can put it back, and then loosen and turn the adjustment so the choke has a lot of pressure on it to keep it open. Then try it. Just to make sure your choke is not borderline on the adjustment.
Thread Starter
|
Freshman User
Joined: Mar 2015
Posts: 48
Likes: 0
From: Windsor, California
well .... found a problem that may have been contributing to the issue. I unbolted and lifted off the carb today with the intention of giving it a thorough run thru ... and one of the mounting ears broke off!! The one on the front right that also holds the accelerator pump arm. Great way to ruin a new carb huh? Further investigation shows that the previous owner had installed a cheap O'reilly aftermarket 1" carb spacer and I believe it is slightly warped so that it caused stress on this mounting ear. So now what to do with this $300 paperweight? Thinking of JB welding the ear back on since its a clean break and the carb doesn't take a lot of torque to mount .... AND removing that damned 1" spacer! Can't afford another "new" carb. Hopefully this works and sometime down the road I can find a carb at pic-n-pull with a useable base plate to swap out ..... any ideas?
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
The spacer may be there because they got rid of the EGR plate. If you take it off you may need to replace it with something to plug the EGR exhaust holes off.
Do you have anything sticking out where it broke off? Would a large fender washer bridge the break point and put down pressure on the good part of the baseplate? It's not going anywhere with the other 3 bolts, but it needs to be pressed down to seal on that broken corner. Maybe you can jb weld the break and jb weld a large washer on top if you have any meat sticking out to jb weld to.
It does sound like the carb was in a terrible bind, and that was making the throttle sticky.
Do you have anything sticking out where it broke off? Would a large fender washer bridge the break point and put down pressure on the good part of the baseplate? It's not going anywhere with the other 3 bolts, but it needs to be pressed down to seal on that broken corner. Maybe you can jb weld the break and jb weld a large washer on top if you have any meat sticking out to jb weld to.
It does sound like the carb was in a terrible bind, and that was making the throttle sticky.
Trending Topics
Thread Starter
|
Freshman User
Joined: Mar 2015
Posts: 48
Likes: 0
From: Windsor, California
I kinda have to JB weld the broken piece back on if I want the accelerator pump to function ... the actuating arm is attached to that piece. I've used JB Weld in many other applications and been rather happy with it so considering the low torque (10-12lbs) to mount the carb I think it should be strong enough to hold. As for the carb spacer ... the EGR is intact ... looks like the previous owner bought into the hype of getting amazing horsepower gains from a 1" spacer and that was the only reason it was installed .... so I am gonna trash it and hope that and the JB weld solve my latest issues ..... nightmare
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
While you are in there, if your intake has a separate spacer just for the egr, I would take that spacer off and replace the gasket underneath and check the surface of the spacer to make sure it's not corroded away. Another spot for jb weld if it is.
Some intakes have the mount for the egr cast into the intake itself, so those kinds don't have the gasket/egr spacer problems.
Some intakes have the mount for the egr cast into the intake itself, so those kinds don't have the gasket/egr spacer problems.
Thread Starter
|
Freshman User
Joined: Mar 2015
Posts: 48
Likes: 0
From: Windsor, California
Way ahead of ya on that one. No corrosion under the EGR plate but I took it off and cleaned the mounting surface just to be sure. I don't want any shear force on the JB Welded mounting ear. Before I removed that crappy 1" spacer I put a little hand pressure on it and it was warped enough to rock back and forth from corner to damaged corner close to a 16th of an inch !!! No wonder the carb mounting ear broke when I torqued it down ... can't bend that pot metal even a 32nd let alone 16th of an inch. With it off the mounting surface is flat as its supposed to be so I am hoping the JB Weld will hold and I will be good to go until I can find a junk yard (pic-n-pull) base plate to swap out. I will know tomorrow .... gonna give it a full 24hrs to cure before I try.
Thread Starter
|
Freshman User
Joined: Mar 2015
Posts: 48
Likes: 0
From: Windsor, California
Just got another question for you more experienced guys here .... my "new" carb has the throttle kickdown bracket attached to the throttle body. My old one doesn't have it .... considering this is on a 4spd manual... now it moves freely so I figured it was no biggie to leave it instead of dealing with removing it and any additional issues that would come along with that. So please correct me if I am wrong in my assumption that leaving it one the carb is not a problem. No spring attached etc .... because, again, this is a manual not automatic.
Thanks
Thanks
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
It depends on what type of "kickdown" it is. Some are just dashpots with no wires going to them. They are like a time delay, letting the throttle back gently when you raise your foot off the pedal. Some have wires and are used to kick up the rpms for A/C. I believe the other day someone was talking about a vacuum operated unit that was hooked into the emissions hoses.
It all depends what it's used for, but more than likely you can leave it off.
It all depends what it's used for, but more than likely you can leave it off.
Thread Starter
|
Freshman User
Joined: Mar 2015
Posts: 48
Likes: 0
From: Windsor, California
oh well JB Weld did not work. So I am screwed. Got a $300 paperweight. only other option I have is to find another 4180c baseplate and swap it out, Went to pic-n-pull today .... no luck. Any ideas on where to get a base plate that will fit the 4180c? I checked the regular places and nobody sells a baseplate for that model .... seems Holley really doesn't support the 4180c any longer. And with nothing at the junkyard I am not sure what to do .... not to mention I need to get this truck back on the road ASAP because I have no other wheels .....
Thread
Thread Starter
Forum
Replies
Last Post
Dean88
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
8
Apr 19, 2009 11:13 PM
alexjp91
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
26
Apr 6, 2008 11:13 PM
sethro
Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460)
7
Feb 10, 2003 11:53 PM