Carb Jet Thread Sizes
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More Turbo
Joined: May 2012
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From: San Antonio
Carb Jet Thread Sizes
I went to install the jets today on my '64 292 with 2100 2bbl (C3TF-9510) and the threads are noticeably bigger than the ones on my carb. Are there two differ size jet threads or did Allstate Carburetor and Fuels Injection send the wrong jets? I called them but they are closed on the weekends.
The engine is running rich enough to soot the side of the truck. All the ignition parts have been replaced and the valves are adjusted. I can turn the idle screws in and kill the motor which I understand indicates the power valve is good. I ordered size 48 jets to make sure the carb was back to factor specs. I thought that would be an easy $10 item fix, Now I am wondering if that was a good move.
The engine is running rich enough to soot the side of the truck. All the ignition parts have been replaced and the valves are adjusted. I can turn the idle screws in and kill the motor which I understand indicates the power valve is good. I ordered size 48 jets to make sure the carb was back to factor specs. I thought that would be an easy $10 item fix, Now I am wondering if that was a good move.
Cargo Master
Joined: Jul 2006
Posts: 3,014
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From: Concord, CA
Take a look here where another size Autolite jet is mentioned for early, like 1963 and older, 4100 and 2100s.
Autolite & Motorcraft Carburetor Jets | 1100 2100 4100
Autolite & Motorcraft Carburetor Jets | 1100 2100 4100
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More Turbo
Joined: May 2012
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From: San Antonio
Thank you. I went to their site and found the correct size. They did good job of leading you to the correct thread size. Allstate could learn from them. I could not order by CC for some reason but will give them a call tomorrow and hopefully have them by the weekend.
At least now I have practice changing the jets. I am no longer apprehensive about changing the jets. I takes 5 minutes max.
At least now I have practice changing the jets. I am no longer apprehensive about changing the jets. I takes 5 minutes max.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
It will be one of the following: C3TF-9510-J or K or T or U or V or Y or Z
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Joined: May 2012
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From: San Antonio
Do you think it is worth $7 to replace th power valve just to make sure it is not leaking a little and make the engine run rich. Cylinders 7 and 8 are the blackest spark plugs.
Lead Driver
Joined: Aug 2003
Posts: 6,305
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From: Boulder Creek, Ca
See if the 48 jets lean it to the where the proper air/fuel mixture can be dialed in; may need to try couple different size jets? Not familiar with that carburetor, or 2bbl carbs in general; having said that, suggest check manufacturer's spec's whether the size jets determine the size of the power valve; or perhaps, one size power valve fits all?
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
Bill, the tag is long gone. Where on the body can you find the numbers? I know I verified the part number before I put it on 2 years ago. The specs in the Shop Manual are all the same for the venturi, jets, and power valve.
What differences do the subfixes notate?
Which specific carb it is.
What differences do the subfixes notate?
Which specific carb it is.
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Post Fiend
Joined: Apr 2002
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From: Waterloo, Iowa
Stupid question, and I'm sure you know this - but is the float level correct? Had a problem with fouled plugs until that was dialed in. It may be that today's fuel expands a bit more or something, not sure, but lowering float a bit seemed to really help.
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More Turbo
Joined: May 2012
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From: San Antonio
The shop manual indicated 29/32 and the best I can tell is it is couple ticks shy of an inch. So it is real close. I was not sure how precise it needed to be. I found the right size jets so I am going to start there and change the power valve just in case it is leaking then go from there. #7 and #8 are the main culprits. So a couple of fresh plugs then run her for a while.
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
Some people claim that today's ethanol-laced, oxygenated gasoline expands more under heat, maybe requiring a bit lower (initial) float level.. Another thing to check is fuel pump pressure, if it's too high it will cause this. Thing to remember, stock jetting should be real close unless you're at altitude.
Pretty sure tweaking float level solved my plug fouling, but I did a real careful idle screw adjustment too and other tuneup stuff as well. A reman distributor seemed to really tighten up the idle as well, it never idled right before that, and the exhaust was pretty stinky. It's amazing how precision a carb can meter the fuel when everything is setup right - just a millimeter tweak of the idle screws makes a huge difference in idle speed and quality.
Pretty sure tweaking float level solved my plug fouling, but I did a real careful idle screw adjustment too and other tuneup stuff as well. A reman distributor seemed to really tighten up the idle as well, it never idled right before that, and the exhaust was pretty stinky. It's amazing how precision a carb can meter the fuel when everything is setup right - just a millimeter tweak of the idle screws makes a huge difference in idle speed and quality.
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From: San Antonio
Thanks for the tips. I have a steady timing light which I take as a sign the timing chain is not stretched. The distributor advances smoothly for what that is worth. There is a company in CA that will rebuild and re-curve the distributor for modern gas for around $100. I just have not wanted to left my tuck set for 2 weeks while the distributor shipped around the country.
She smells fine at idle. It is on the road she sticks bad enough my wife can smell it when she follows me. The new jet will be here in a couple days. I will see if that helps, then proceed.
She smells fine at idle. It is on the road she sticks bad enough my wife can smell it when she follows me. The new jet will be here in a couple days. I will see if that helps, then proceed.
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
I've got an extry dizzy (needs rebuild) you can have for postage ifn you wanted to go that route. It's the 57 and later style, course. C3TF iirc. I'm the same way, gotta keep up my operational readiness rate 
Two weeks down is definitely unsatisfactory.
Two weeks down is definitely unsatisfactory.
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From: San Antonio
Dropped the new jets in went for a drive to warm up the engine. She was stumbling when cold and liked a little choke. Full choke gives visible black smoke so I have some more work to get the choke right. She would not idle even after running a few minutes. I adjusted the idle mixture and speed cleaned the soot off the side of the truck went for a 40 mile drive. No new soot on the side of the truck. I think she is dialed in for the fuel. Some stumbling between 1000-1700 under full load, but that lessened lessoned with miles so she may have not been at operating temp.
The old jets were marked 48 but I think they have been drilled. Now she shows sign of running lean when cold. That was not an issue before. But mainly No More Soot.
The old jets were marked 48 but I think they have been drilled. Now she shows sign of running lean when cold. That was not an issue before. But mainly No More Soot.
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