stripped needle and seat threads
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Joined: Feb 2009
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stripped needle and seat threads
I've got a 76 f100 with the 390fe and a 4 bbl holley 4150 650 cfm carb on top.
Problem is, I replaced the mech fuel pump with a #12s Mr Gasket 4-9 pound electric pump (due to worn mechanical drive lobe) which caused the secondaries to fountain fuel out of the angled vent tube thing. i tightened up the needle and seat, and it came back to a more or less tuned mixture, when the seat nut started leaking huge amounts of fuel, and i discovered that i had stripped all of the threads off of the bowl.
I was out of town so i took of the secondary bowl/metering block to drive home, ordered another bowl from holley and installed it
3 months later it happens again, but with the primary's
Truck is now running with the new secondary bowl installed on the primary metering block on the front of the carb, with no secondaries.
what the eff is happening and how do i quit my floatbowl addicition
Problem is, I replaced the mech fuel pump with a #12s Mr Gasket 4-9 pound electric pump (due to worn mechanical drive lobe) which caused the secondaries to fountain fuel out of the angled vent tube thing. i tightened up the needle and seat, and it came back to a more or less tuned mixture, when the seat nut started leaking huge amounts of fuel, and i discovered that i had stripped all of the threads off of the bowl.
I was out of town so i took of the secondary bowl/metering block to drive home, ordered another bowl from holley and installed it
3 months later it happens again, but with the primary's
Truck is now running with the new secondary bowl installed on the primary metering block on the front of the carb, with no secondaries.
what the eff is happening and how do i quit my floatbowl addicition
Logistics Pro
Joined: Oct 2005
Posts: 3,785
Likes: 4
From: Mddl A MexCans
I've got a 76 f100 with the 390fe and a 4 bbl holley 4150 650 cfm carb on top.
Problem is, I replaced the mech fuel pump with a #12s Mr Gasket 4-9 pound electric pump (due to worn mechanical drive lobe) which caused the secondaries to fountain fuel out of the angled vent tube thing. i tightened up the needle and seat, and it came back to a more or less tuned mixture, when the seat nut started leaking huge amounts of fuel, and i discovered that i had stripped all of the threads off of the bowl.
I was out of town so i took of the secondary bowl/metering block to drive home, ordered another bowl from holley and installed it
3 months later it happens again, but with the primary's
Truck is now running with the new secondary bowl installed on the primary metering block on the front of the carb, with no secondaries.
what the eff is happening and how do i quit my floatbowl addicition
Problem is, I replaced the mech fuel pump with a #12s Mr Gasket 4-9 pound electric pump (due to worn mechanical drive lobe) which caused the secondaries to fountain fuel out of the angled vent tube thing. i tightened up the needle and seat, and it came back to a more or less tuned mixture, when the seat nut started leaking huge amounts of fuel, and i discovered that i had stripped all of the threads off of the bowl.
I was out of town so i took of the secondary bowl/metering block to drive home, ordered another bowl from holley and installed it
3 months later it happens again, but with the primary's
Truck is now running with the new secondary bowl installed on the primary metering block on the front of the carb, with no secondaries.
what the eff is happening and how do i quit my floatbowl addicition
As to the threads getting stripped out. Sounds like a domino effect scenario.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
Welcome to FTE.
Sounds like the rear needle/seat was worn, thus the spewing fuel. ( or just a piece of dirt in them). Do you have a filter inline?
The leaking around the adj nut is all due to poor gaskets. If you don't have nice, clean paper gaskets under the nut and top screw, then IT WILL LEAK!!! It shouldn't take but a very, very LIGHT twist of the screwdriver to snug it down after adjusting it. Any more and it will strip the threads from the bowl(you found out).
Never heard of worn pump cam either? It's hardened and if it's gone, then something is seriously wrong.
Question: Are you using real Holley needle/seats, or the aftermarket version that doesn't have the flat machine screw on top?(only a nut). The true Holley version work better, but still it all boils down to overtightening caused the stripped threads(usually due to poor gaskets).
I have dual quads on THREE vehicles(all Holleys), so I'm pretty versed in keeping them alive.
Sounds like the rear needle/seat was worn, thus the spewing fuel. ( or just a piece of dirt in them). Do you have a filter inline?
The leaking around the adj nut is all due to poor gaskets. If you don't have nice, clean paper gaskets under the nut and top screw, then IT WILL LEAK!!! It shouldn't take but a very, very LIGHT twist of the screwdriver to snug it down after adjusting it. Any more and it will strip the threads from the bowl(you found out).
Never heard of worn pump cam either? It's hardened and if it's gone, then something is seriously wrong.
Question: Are you using real Holley needle/seats, or the aftermarket version that doesn't have the flat machine screw on top?(only a nut). The true Holley version work better, but still it all boils down to overtightening caused the stripped threads(usually due to poor gaskets).
I have dual quads on THREE vehicles(all Holleys), so I'm pretty versed in keeping them alive.
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
The bowls on the Holley carbs are cheap aluminum castings and if you get the least bit torque crazy they strip in a micro-second. Gentle is the word when working with Holley needle and seats. Tight enough to no leak, and no tighter.
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