Carb Metering Jets
Senior User
Joined: Jun 2001
Posts: 200
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From: Davis, CA
Carb Metering Jets
So far, I've never heard, on this board or anywhere else, about the factory size jets. But I've been running #60's in my 400, and I tested it on the exhaust analyzer, and its been running just about right. I tested 51's, and 56's, and both were way too lean. Took some serious pedal to get her movin. I'm even thinkin about goin to 62's.
Posting Guru
Joined: Aug 2000
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Carb Metering Jets
My 78 351M came with #57's from the factory. They were too lean when I disconnected the EGR, so (like Fordman) I went up to #60's. These are just about right. I think that Ford intentionally jetted these model years a little lean for lower emissions. Bigger jets make them run MUCH better.
New User
Joined: Feb 2002
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Carb Metering Jets
there is something that i would like to ask i have a ford f 250with a 351m motor also and i am haveing trouble getting the fuel mixture rite would any one have any info on how many turns it should be on left and rite side of the carb the carb is a 2150thnx everyone lou
New User
Joined: Jan 2008
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Carb Metering Jets
This is for idle mixture ONLY.
First make sure all the mechanical tune-up items are done.
Timing,Vacuum Advance is Working(not seized),Idle speed is set.
Now,Turn one the screws in just until the engine starts to stumble,Next (while counting the exact amount of turns)turn the screw out until the engine starts to stumble,Next, Turn the screw back IN half the amount of turns you counted,
Repeat for the other side>
Reset the idle to spec and you're done.
This procedure will get you Very,Very close to optimal position.
The other way is with a vacuum gauge.
Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg
Please Don't Ask Me Any Tough Questions As:
"I'm Saving My Memory For When I Develop Alzheimer's"
78 F-150 429CJ,Silver
w/Explorer Pkge.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon
First make sure all the mechanical tune-up items are done.
Timing,Vacuum Advance is Working(not seized),Idle speed is set.
Now,Turn one the screws in just until the engine starts to stumble,Next (while counting the exact amount of turns)turn the screw out until the engine starts to stumble,Next, Turn the screw back IN half the amount of turns you counted,
Repeat for the other side>
Reset the idle to spec and you're done.
This procedure will get you Very,Very close to optimal position.
The other way is with a vacuum gauge.
Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg
Please Don't Ask Me Any Tough Questions As:
"I'm Saving My Memory For When I Develop Alzheimer's"
78 F-150 429CJ,Silver
w/Explorer Pkge.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V
84 Volvo DL Wagon
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