carb help!
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Senior User
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carb help!
i just replaced my motorcraft 2150 2 bbl with a used holley 1850 4 bbl. this is my first 4 bbl so i have a couple questions. the seocndary throttle plates arent closing all the way. i can force them to close but if i floor it and they open they wont close all the way again, and my truck will idle at like 2500-3000 rpm in park. when i put it in drive it drops down to 1500 but thats still real high. is it the secondary spring i need to replace? also i m wondering about the choke. it didnt come with one and its a pain to start it. would it be worth it to just put an electric one on even though it was supposed to be equipped with the manual choke?
thanks for the help.
thanks for the help.
Senior User
Joined: Apr 2006
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From: St Lawrence Valley - NY
not real familiar with any but the 4100 series but i know that if you don't double check the gasket size and alignment it can catch the butterflies and bind enough to prevent closing (had it happen before). loosen the carb base mounting bolts first and see if your secondaries close. might have to shimmy it around slightly. keep checking the butterflies for any binding as you retighten. also i've seen gaskets not cut properly and need hand trimming before a carb mount.
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From: Virginia
I have had the secondary problem before, and what fixed mine was to loosen the phillips head screw on the passenger side of the carb underneath the secondary diaphragm. This is the screw that goes into the sec throttle shaft. Loosen it, and then re-tighten it.
If that doesn't fix it, then look on the driver's side of the carb. There should be a lever that is linked with the primary throttle shaft. When the throttle is closed, this lever should force the secondaries shut.
If you do not have a choke door on top of the carb, then you are going to have to hunt one of those up on a junk carb, or order one from Holley. The electric choke kits you can buy only have the mechanism on the side of the carb. They assume you have the choke door itself still there.(I am assuming that's what you meant by it being gone).
If that doesn't fix it, then look on the driver's side of the carb. There should be a lever that is linked with the primary throttle shaft. When the throttle is closed, this lever should force the secondaries shut.
If you do not have a choke door on top of the carb, then you are going to have to hunt one of those up on a junk carb, or order one from Holley. The electric choke kits you can buy only have the mechanism on the side of the carb. They assume you have the choke door itself still there.(I am assuming that's what you meant by it being gone).
Old School Hot Rodder
Joined: Feb 2006
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From: Exmore, VA
Shame you're too far away. I think I still have a complete O-1850-3 in my garage. Before you actually mess with the secondary diaphram, take the clip loose from the throttle lever the diapram attaches to. With it disconnected and the engine NOT RUNNING! hold the primaries all the way open, then see if the secondaries move freely open and closed. If not, then you need to look at the mountings and make sure they aren't binding. If you find the diaphram rod won't come all the way down, then that is your problem. Good luck!
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the secondaries arent binding, they move freely when the primarys are wide open. the lever on the throttle shaft moves a little causing the secondaries to open and close a little.
but i found another problem. the secondaries leak fuel into the engine even with the engine off. it just drips in. how would i fix this? replace the jets?
but i found another problem. the secondaries leak fuel into the engine even with the engine off. it just drips in. how would i fix this? replace the jets?
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From: Virginia
You should have a site plug on the passenger side of the carb, both front and rear. Take the rear one out. If fuel gushed out, then the float level is too high. Do you know how to adjust the float level?
You need to take the front site plug out and check the front too. The correct level is when it's just below the hole, and you can shake the truck and it sloshes out a little bit.
You need to take the front site plug out and check the front too. The correct level is when it's just below the hole, and you can shake the truck and it sloshes out a little bit.
Old School Hot Rodder
Joined: Feb 2006
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From: Exmore, VA
Franklin, I don't think the 4180 has externally adjustable needles and seats. I have run into warped secondary meetering bodies on them though. It is sort of dark right now, I can look tomorrow at mine.
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ok. i dont know how to adjust float levles. im about to put my old motorcraft 2bbl on and then rebuild the holley.
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pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
Here's the tech on Holley's site, it's the third item.
http://www.holley.com/TechService/FAQ.asp
Google works!
http://www.holley.com/TechService/FAQ.asp
Google works!
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thanks for the link. im gonna check that out tommorow.
i just noticed that on my motorcraft 2150 carb there is what appears to be a vacuum port on the electric choke houdsing. could that be for the pcv because i dont have a place to hook one up on the carb.
i just noticed that on my motorcraft 2150 carb there is what appears to be a vacuum port on the electric choke houdsing. could that be for the pcv because i dont have a place to hook one up on the carb.
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From: Virginia
Originally Posted by 85lebaront2
Franklin, I don't think the 4180 has externally adjustable needles and seats. I have run into warped secondary meetering bodies on them though. It is sort of dark right now, I can look tomorrow at mine.
Pull the site level screws out of the side of the bowels first and see what the fuel level is.
On the old motorcraft, the PCV usually has a large port on the front of the carb. Since you have the Holley carb, I would not mess with the 2bbl anymore. I hope you have a 4bbl manifold on the engine.
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
Originally Posted by alexjp91
i just noticed that on my motorcraft 2150 carb there is what appears to be a vacuum port on the electric choke houdsing. could that be for the pcv because i dont have a place to hook one up on the carb.
Sure it's not an electrical connection? My 4180 has a single bullet type connector on the electric choke housing.
There's no big port in the bottom flange for the PCV?
if you poke around Holley's site they have spec's for all kinds of stuff like jetting, even Motorcraft.
You could even hook the PCV to a manifold port, I don't know what manifold, or even what truck you have.
Yes, go ahead and get an electric choke for your 1850. It will make your life much easier. They have the conversion kit #'s and pdf of the instructions on that site.
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From: Virginia
If the fuel level is ok, then the fuel is probably leaking from the secondaries because of all the air flowing by them. If you can get the rear secondaries shut, then the fuel may stop flowing. If someone has taken the butterflies off the throttle shaft, and got them out of wack, then they may not seat correctly when the throttle is shut. No matter what carb you are rebuilding NEVER take the butterflies off the throttle shafts, unless you are re-bushing the carb body which most people should not/cannot do anyway.
Last edited by Franklin2; Mar 29, 2008 at 10:15 AM.