carb port question
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Elder User
Joined: May 2004
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carb port question
351m,77 1/2f2504x4
i ordered a new carb(2150) for my truck, old one has big port in back for pcv and small port next to it(drivers side) for vac. adv.
new one has no big or small port in back, and has the port in front next to enrichment screws(drivers side)
I hooked up the new carb and ran pcv to port in intake manifold located in front and off to the passenger side of the carb. ran vac adv to port near enrichment screws( i was told that my old carb should have had the adv. line run to this port in the first place but it ran fine so i left it)
here's what happened
didnt want to idle, very rough, tried to drive up the street and many backfires through the carb. put the old one back on(very frustrated) and went to work. now i have a new carb in a box.
are there any differences between motorcraft2150, and autolite 2150?
how do i hook this carb up if i even can? any help is appreciated.
i ordered a new carb(2150) for my truck, old one has big port in back for pcv and small port next to it(drivers side) for vac. adv.
new one has no big or small port in back, and has the port in front next to enrichment screws(drivers side)
I hooked up the new carb and ran pcv to port in intake manifold located in front and off to the passenger side of the carb. ran vac adv to port near enrichment screws( i was told that my old carb should have had the adv. line run to this port in the first place but it ran fine so i left it)
here's what happened
didnt want to idle, very rough, tried to drive up the street and many backfires through the carb. put the old one back on(very frustrated) and went to work. now i have a new carb in a box.
are there any differences between motorcraft2150, and autolite 2150?
how do i hook this carb up if i even can? any help is appreciated.
Elder User
Joined: Mar 2003
Posts: 788
Likes: 1
From: Hendersonville, TN
The difference MAY be that one was for EGR manifold and the other wasn't. As far as the PCV, if it's hooked up to most any large port on the manifold this should be OK. The vacuum advance line should go to a "spark ported" vacuum port, meaning one that is above the throttle blades. Try blowing into the vacuum ports on the carb and see where the air comes out. If it is below the throttle blades it's manifold vacuum, if it's above the blades it's ported. Sounds like you hooked up to manifold vacuum, which would be high at idle, causing the vacuum advance to go to full advance right at and just above idle. If it's too advanced then the timing will be advanced and fire the plugs too soon(like while the intake valve is still open) causing a backfire through the carb. Was this supposed to be an exact replacement carb. If so, then I'd take it back and tell them they got you the wrong carb. If that's the case, it could also be jetted wrong as well.
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Elder User
Joined: May 2004
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thank you for the reply, i bet i did exactly what you said i did. this was supposed to be an exact replacement. i think i will try hooking it up again with a different vac. source before sending it back as i ordered it and am anxious to be getting better gas milage. by the way i do have the egr valve but no cat and no charcoal canister. i think im somewhere inbetween legal and not legal.
thanks again
thanks again
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