1981 YFA carb jetting
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Cross-Country
Joined: Apr 2012
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1981 YFA carb jetting
Hi- I am new to this forum, but have read a lot here.I am doing a rebuild on my E150 YFA carb,and have a couple of questions.The previous owner put a manual choke on the van.I would like to go back electric,and can't find the power wire anywhere.Where did it originally come from?There is a wire ,on the drivers side of the motor,about in the middle,coming from the main loom, but it is never powered,(key off or key on).It was cut, and is just stickin out there.
Other thing is I am at about 6000 feet altitude,and the sticker,(under the hood/on the hood), says it is good up to 4000 feet.Should I rejet/rerod now? Where would I find, or does someone have the rod/jet numbers, or part numbers,for altitude?
Thanks in advance for your help,I hope I am not revisiting a previous discussion, or offending anyone.
When I was a younger guy, we had a 1 ton pickup,with a 4.9,that I pulled a 5000 pound trailer ,with a full size Allis Chalmers grading tractor and box scraper with ,on a regular basis.I have RESPECT for the 4.9.
Oh yeah, one other thing, I need a vacuum diagram,to get all the hoses back in order.
Other thing is I am at about 6000 feet altitude,and the sticker,(under the hood/on the hood), says it is good up to 4000 feet.Should I rejet/rerod now? Where would I find, or does someone have the rod/jet numbers, or part numbers,for altitude?
Thanks in advance for your help,I hope I am not revisiting a previous discussion, or offending anyone.
When I was a younger guy, we had a 1 ton pickup,with a 4.9,that I pulled a 5000 pound trailer ,with a full size Allis Chalmers grading tractor and box scraper with ,on a regular basis.I have RESPECT for the 4.9.
Oh yeah, one other thing, I need a vacuum diagram,to get all the hoses back in order.
Lead Driver
Joined: Jul 2009
Posts: 6,477
Likes: 19
From: Sheffield, AL
Welcome to the forum, maf226!
The power for the electric choke assist [also had a tube coming from exhaust manifold to the choke housing] was supplied by the alternator [s post, I believe... someone else will make sure]. This supplied ~7 volts to the choke heating element only when the alternator was turning. That might be why you are not getting voltage, if you checked it with the engine not running. FORD designed it so that the choke would not start opening if the key was in the "on" position but the engine had not yet been started.
The power for the electric choke assist [also had a tube coming from exhaust manifold to the choke housing] was supplied by the alternator [s post, I believe... someone else will make sure]. This supplied ~7 volts to the choke heating element only when the alternator was turning. That might be why you are not getting voltage, if you checked it with the engine not running. FORD designed it so that the choke would not start opening if the key was in the "on" position but the engine had not yet been started.
Moderator
Joined: Dec 2007
Posts: 7,987
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From: Boise, Idaho
There should be a sticker on the radiator support with a complete vacuum diagram.
But if not, let me know. I have an '81, so I can snap a pick of it.
For 6000 feet, I would definitely say you need to rejet. I don't know how Carter jet sizes work, but if you pull the cap off the carburetor, you can disassemble the metering rod assembly and remove the jet without removing the carb from the vehicle. The size of the jet should be printed on the jet itself.
You can find lots of jet replacements at Allcarbs.com. It's a great site with TONS of carb parts. I don't see a listing for Carter jets specifically, but there is a listing for Motorcraft/Ford/Autolite jets, which I think are them. Give the guy an email and ask if you need to. He's really helpful and usually gets back to emails quickly, sometimes within the hour.
I don't think you'd need to mess with the metering rod.
But if not, let me know. I have an '81, so I can snap a pick of it.
For 6000 feet, I would definitely say you need to rejet. I don't know how Carter jet sizes work, but if you pull the cap off the carburetor, you can disassemble the metering rod assembly and remove the jet without removing the carb from the vehicle. The size of the jet should be printed on the jet itself.
You can find lots of jet replacements at Allcarbs.com. It's a great site with TONS of carb parts. I don't see a listing for Carter jets specifically, but there is a listing for Motorcraft/Ford/Autolite jets, which I think are them. Give the guy an email and ask if you need to. He's really helpful and usually gets back to emails quickly, sometimes within the hour.
I don't think you'd need to mess with the metering rod.
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Cross-Country
Joined: Apr 2012
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You were right
1986 F150 six, I tested the wire today, and it is hot while running, and off when the key is on.
I ordered a vaccum /wiring manual,(OEM Ford), and it shows the vaccum allright,but only for the dash!!!
The Ford shop manual,on the other hand,shows GREAT carb rebuild/adjustment instructions, and puts the carb kit directions to shame.I would not rebuild a carb,on one of these ,without the OEM shop manual.(FYI)
Another interesting shop manual tidbit,the Duraspark unit,for high altitude, is a three plug unit, with the third plug going to a barometric pressure sensor,that alters timing curve, based on altitude.
The carb guy,you told me about was super, but needs the Carter carb number, on the side of the body.I have the original Ford tag, but he can't get the jet size from that.With my truck being a van, I will have to take it out/off again ,to get the number, or rejet.
After I rebuilt the carb, it runs so well, I may try for emissions first, and see if it will pass this way.
Thanks again, for putting me on the right track.
I ordered a vaccum /wiring manual,(OEM Ford), and it shows the vaccum allright,but only for the dash!!!
The Ford shop manual,on the other hand,shows GREAT carb rebuild/adjustment instructions, and puts the carb kit directions to shame.I would not rebuild a carb,on one of these ,without the OEM shop manual.(FYI)
Another interesting shop manual tidbit,the Duraspark unit,for high altitude, is a three plug unit, with the third plug going to a barometric pressure sensor,that alters timing curve, based on altitude.
The carb guy,you told me about was super, but needs the Carter carb number, on the side of the body.I have the original Ford tag, but he can't get the jet size from that.With my truck being a van, I will have to take it out/off again ,to get the number, or rejet.
After I rebuilt the carb, it runs so well, I may try for emissions first, and see if it will pass this way.
Thanks again, for putting me on the right track.
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Heya Maf226,
Glad to hear you got it rebuilt and it's running great. That's always a good feeling.
Let us know how the emissions testing goes. That, often, can be an indicator as well if you need to rejet or not. Especially if all your other emissions equipment is up to spec.
Glad to hear you got it rebuilt and it's running great. That's always a good feeling.
Let us know how the emissions testing goes. That, often, can be an indicator as well if you need to rejet or not. Especially if all your other emissions equipment is up to spec.
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Cross-Country
Joined: Apr 2012
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I want....
There is a Duraspark unit for high altitude, that has 3 plugs coming from it,and the third is a barometric pressure sensor,that loops right back into the Duraspark unit.
Mine is a standard transmission carburated 4.9.
I would like to buy one, new or used,
. I tried to post in wanted , but it says I can't,do I have to be an upgraded member?
Mine is a standard transmission carburated 4.9.
I would like to buy one, new or used,
. I tried to post in wanted , but it says I can't,do I have to be an upgraded member?
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Lead Driver
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From: Sheffield, AL
Not sure about an "upgraded member", but you have to have made 25 posts before you can PM, so maybe the same applies to being able to post in the classifieds. This is to lessen the chances that someone will just "pop" on the scene to sell something. We are members first to assist each other and second to buy or sell items. 
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Cross-Country
Joined: Apr 2012
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Anyone have access to a Ford parts book?
I also could use the correct Ford part number for the High Altitude Duraspark unit for my 1981 Econoline 4.9, manual transmission.
If it is available. Thanks!!
If it is available. Thanks!!
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