help on carb tuning
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Freshman User
Joined: Jun 2004
Posts: 38
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help on carb tuning
hey.....i have a 75 f100 4x4 shorty (sport model) with a 390gt and i was wondering if anyone could give me some tips on tuning the carb.......i am 16 and have changed the engine twice and i can play with the carb and make it run better.....but its never perfect......and i want perfect!
its a 2bbl motocraft (i dont know the model number) it was off of a 73 f250 i also have a holley 600cfm 4bbl i want to put on soon but the 2bbl will have dto do b/c at 2.00 a gallon and 7-11 mpg im not going to run a 4bbl right now
its a 2bbl motocraft (i dont know the model number) it was off of a 73 f250 i also have a holley 600cfm 4bbl i want to put on soon but the 2bbl will have dto do b/c at 2.00 a gallon and 7-11 mpg im not going to run a 4bbl right now
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
The 4 barrel will probaly give you better mileage that the 2 barrel if you keep you fat foot out of it. They almost aways do. Tuning the 2V motorcraft is just like you would a holley 2 or 4 barrel. Except that the mixture screws are under the float bowl in the front of the base plate. Starting point, 1 1/2 turns out on each screw. Let engine warm completely up (go drive it for ten minutes) then screw either screw in slowly, when engine rpm starts to drop then back it out to the fast rpm then to where the rpms drop again half way between these to points should be fastest idle speed. Now do the other screw the same way. Now go back and check the first one and if you move it do the second screw again too. I have a good ear for rpm changes but you might want to use a tach. A vacuum guage will work also, adjust for highest vacuum (same result as highest rpm will give you highest vacuum and visa-versa) After you are done adjusting the mixture screw set the idle speed at the throttle linkage for 600 rpms, with a auto tranny do it in gear.
