Carb jetting and elevation
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Trailering
Joined: Feb 2014
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Carb jetting and elevation
I just bought an 82 f100 with the 300 and 1 barrel carter carb. I pulled the jet because I live at 10000 ft in colorado and I was thinking I need to re jet. I can’t see the number on the jet. Anyone know what jet size I would need for a carter 1bbl at 10k feet. Thank you
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From: Virginia
One number I found was go smaller 1 jet size for every 2000ft. So that would be 5 jet sizes for you.
I would call these people in the morning. https://www.carburetor-parts.com/carter-metering-jets
Looks like the smallest jet they sell is a #51. I would first ask them could you take the jet to a machine shop and get them to try drill bits in the jet you have till one fits. Sometimes the jets are sized by number drills, you could ask them about that. If they are, a local machine shop will have number drill bits or precision sizing pins that they can use to check what you have. Once you know your starting point you can go down from there. I think I would order several different sizes.
I would call these people in the morning. https://www.carburetor-parts.com/carter-metering-jets
Looks like the smallest jet they sell is a #51. I would first ask them could you take the jet to a machine shop and get them to try drill bits in the jet you have till one fits. Sometimes the jets are sized by number drills, you could ask them about that. If they are, a local machine shop will have number drill bits or precision sizing pins that they can use to check what you have. Once you know your starting point you can go down from there. I think I would order several different sizes.
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Joined: Jan 2001
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From: Virginia
Here is some sort of chart they have on their page also. These might be actual sizes in inches. If they are, then the machine shop can measure and see what you have.
https://www.carburetor-parts.com/carter-jet-conversion
https://www.carburetor-parts.com/carter-jet-conversion
FTE Legend
Joined: Nov 2015
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From: Angier, NC
FYI the Carter YF has adjustable needle & seat.
I dont know if the needles & seats are sized for each other or if you can mix & match?
I can tell you you can make adjustments, rich or lean with out opening the carb once you know what the adjusting screw looks like.
So if you are looking to adjust rich lean I dont see the need to change anything in the carb.
I will say install a AFR gauge (air fuel ratio) so you know just what is going on when you make adjustments.
Dave ----
I dont know if the needles & seats are sized for each other or if you can mix & match?
I can tell you you can make adjustments, rich or lean with out opening the carb once you know what the adjusting screw looks like.
So if you are looking to adjust rich lean I dont see the need to change anything in the carb.
I will say install a AFR gauge (air fuel ratio) so you know just what is going on when you make adjustments.
Dave ----
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Joined: Jan 2001
Posts: 56,980
Likes: 2,735
From: Virginia
FYI the Carter YF has adjustable needle & seat.
I dont know if the needles & seats are sized for each other or if you can mix & match?
I can tell you you can make adjustments, rich or lean with out opening the carb once you know what the adjusting screw looks like.
So if you are looking to adjust rich lean I dont see the need to change anything in the carb.
I will say install a AFR gauge (air fuel ratio) so you know just what is going on when you make adjustments.
Dave ----
I dont know if the needles & seats are sized for each other or if you can mix & match?
I can tell you you can make adjustments, rich or lean with out opening the carb once you know what the adjusting screw looks like.
So if you are looking to adjust rich lean I dont see the need to change anything in the carb.
I will say install a AFR gauge (air fuel ratio) so you know just what is going on when you make adjustments.
Dave ----
But you do have a point, the needle and seat work together so he might have to get another needle also. I hope those guys in the link above who sell the jets can lead him in the right direction.
FTE Legend
Joined: Nov 2015
Posts: 30,892
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From: Angier, NC
I found with mine depending how far in or out the needle was to the seat will change the AFR at cruise.
My Ebay carb was way too lean and had to make it richer.
Now when you try and go WOT it will show rich from the pump shot but when you back out of it it backs down to the set AFR.
Who can run WOT to know what the AFR would be? I cant even pulling a trailer.
Maybe the link can help him like you said
Dave ----
My Ebay carb was way too lean and had to make it richer.
Now when you try and go WOT it will show rich from the pump shot but when you back out of it it backs down to the set AFR.
Who can run WOT to know what the AFR would be? I cant even pulling a trailer.
Maybe the link can help him like you said
Dave ----
Laughing Gas
Joined: Sep 2016
Posts: 774
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From: Elk Grove Village, IL
I've done this with motorcycles (I'm at about 600' above sea level) and have attempted to re-jet when riding higher altitudes in Colorado. I used the 'tried & true' re-jetting formulas only to discover I went too lean and that I really didn't need to re-jet at all. Could carburetors be forgiving enough to run at any altitude (within reason) which is why Ford wasn't that concerned with it (at the factory)?
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From: Virginia
They will run and get you through, but they will not run their best. They will run about the same as when your power valve goes bad. A little rich, stinky exhaust.
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FTE Legend
Joined: Nov 2015
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From: Angier, NC
I got to thinking if the needle moves off the seat when the throttle, more throttle higher off the seat it comes but so dose more air to keep the seat AFR.
You cant look at the YF v1 carb with its needle & seat working the same as carbs that run just jets.
It has a fixed jet setting where the throttle is changing the air into the motor.
For street you jet that car for cruise only race motors (drag) do you jet for WOT.
Now I believe they may have larger seats / smaller needles so the motor can get more fuel but I dont think our 300 motors need that much of a change.
I would install the AFR gauge first to see where the AFR is before making changes as you will need the gauge for down the road.
My .02
Dave ----
You cant look at the YF v1 carb with its needle & seat working the same as carbs that run just jets.
It has a fixed jet setting where the throttle is changing the air into the motor.
For street you jet that car for cruise only race motors (drag) do you jet for WOT.
Now I believe they may have larger seats / smaller needles so the motor can get more fuel but I dont think our 300 motors need that much of a change.
I would install the AFR gauge first to see where the AFR is before making changes as you will need the gauge for down the road.
My .02
Dave ----
Cargo Master
Joined: Mar 2002
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From: W (BY GOD) V
The easiest way to go about it (IMO) is with the FORD MPC TEXT 9510 PARTS LIST.
ID the CARB in the chart (9510) and it will give you the correct PARTS LIST. Within that list under 9533 (jet) will be an elevation chart and which size jet was used for assembly.
Do you have the CARB ID ASSEMBLY TAG INFO?
ID the CARB in the chart (9510) and it will give you the correct PARTS LIST. Within that list under 9533 (jet) will be an elevation chart and which size jet was used for assembly.
Do you have the CARB ID ASSEMBLY TAG INFO?
Thread Starter
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Trailering
Joined: Feb 2014
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Thank you all for the suggestions. Might get an afr gauge to see where I am at. Don’t have any ID tags unfortunately. I wish I could read that number. But I think I will call that carb company see if they can help me out.
FTE Legend
Joined: Nov 2015
Posts: 30,892
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From: Angier, NC
Let us know how you make out as I think just adjusting the needle will be enough unlike the carb that uses just a jet.
I base this on my Ebay carb that ran really lean through all RPM range.
Once I adjusted the needle it now keeps AFR between 14.5 - 15.5 before it was around 17 and higher.
They say 14.7 is the number to shoot for, lower number is richer.
Dave ----
I base this on my Ebay carb that ran really lean through all RPM range.
Once I adjusted the needle it now keeps AFR between 14.5 - 15.5 before it was around 17 and higher.
They say 14.7 is the number to shoot for, lower number is richer.
Dave ----
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