Carb throttle shaft binds when mounted
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Desk Jockey
Joined: Sep 2021
Posts: 1,067
Likes: 425
From: Raleigh, NC
Carb throttle shaft binds when mounted
351M MC 2150
I am wrapping up my intake reseal job that included an intake refresh, EGR plate cleaning and new carb posts.
Last step is tightening down my 2150 to spec 14 lbs.
But when I tighten my carb mounting nuts, the throttle shaft binds - meaning hard to turn and won’t return when released. If I loosen the mounting nuts, the problem resolves.
I wonder if I am flexing the shaft somehow?
I removed the mounting gasket (thick version) and tested against the EGR plate - no issue. I retested with several different gaskets (thick) - issue returns.
Tightening order has no impact - only relative tightness. A few ft-lbs and it binds.
Possible obstruction on gasket carb mating surface? I tried my old gasket but still had the issue.
On the bench the carb operates smoothly. Same when mounted and not tightened.
Any one bump into this before?
I am wrapping up my intake reseal job that included an intake refresh, EGR plate cleaning and new carb posts.
Last step is tightening down my 2150 to spec 14 lbs.
But when I tighten my carb mounting nuts, the throttle shaft binds - meaning hard to turn and won’t return when released. If I loosen the mounting nuts, the problem resolves.
I wonder if I am flexing the shaft somehow?
I removed the mounting gasket (thick version) and tested against the EGR plate - no issue. I retested with several different gaskets (thick) - issue returns.
Tightening order has no impact - only relative tightness. A few ft-lbs and it binds.
Possible obstruction on gasket carb mating surface? I tried my old gasket but still had the issue.
On the bench the carb operates smoothly. Same when mounted and not tightened.
Any one bump into this before?
Hotshot
Joined: Feb 2004
Posts: 10,808
Likes: 2,604
From: The Shenandoah Valley
I use thinner carb to intake gaskets, as thick ones will compress more under nuts as they push up against no nut areas ... I grease my gaskets too. I also tend to go easy on torque and double nut my nuts. I doubt that I use a full 14 "torques" on them before the second nut..
I once used a thick gasket on a 302 EGR Mustang, busted the carb base.
But yeah, you have something "not flat" there, and those carb bases don't like to flex, so if binding ... check it close for a crack.
I once used a thick gasket on a 302 EGR Mustang, busted the carb base.
But yeah, you have something "not flat" there, and those carb bases don't like to flex, so if binding ... check it close for a crack.
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Desk Jockey
Joined: Sep 2021
Posts: 1,067
Likes: 425
From: Raleigh, NC
Well I decided to use a thin gasket and call it a day. No issues.
I had a collection of 4 thicker gaskets. I tried each one individually. One of them was the prior gasket that worked previously. Everyone of them caused the throttle shaft to bind. Each was identical in size and manufacture.
Not sure. I don’t have a theory on this one. But I suspect Tbear is onto it with the compression of gasket,
I had a collection of 4 thicker gaskets. I tried each one individually. One of them was the prior gasket that worked previously. Everyone of them caused the throttle shaft to bind. Each was identical in size and manufacture.
Not sure. I don’t have a theory on this one. But I suspect Tbear is onto it with the compression of gasket,
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