Carb issues?
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Cross-Country
Joined: Apr 2023
Posts: 51
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Carb issues?
I’m working on a 73 f100 with a 360 in and I’ve been fighting with it since I got it. It’s only running on 4 (5,1, 2, 4). I’ve been through the carb twice now and (I’ll admit late in the game) I checked the compression and all around 100-120 except #6 was at 30 psi. So that’s going to need addressed but I still can’t figure out why I’m missing the other 3. Maybe somebody on here has dealt with this before or can tell me I’m just stupid either way any information is appreciated lol. Thanks Carsten
Cargo Master
Joined: Dec 2015
Posts: 2,549
Likes: 331
From: Harned, Ky
Do you have the pcv connected to one of the intake ports or a the base of the carb
Disconnect any vacuum lines from the intake and plug that port, power brake booster, automatic transmission, vacuum reservoir
The intake is divided into two plenums, one plenum feeds cylinders 2-5-4-8, the other feeds 2-6-3-7. A vacuum leak at one intake runner will lean out and effect all cylinders connected to that plenum. One side of the carburetor not working will affect the 4 cylinders that side feeds. If you have a burnt, warped or stuck intake valve on number 6 cylinder the compression being forced back up through the intake will kill the vacuum drawing fuel to the other 3 cylinders on that side of the intake plenum
Remove the radiator cap and valve cover fill cap, then pull number 6 plug and connect a air source to see where the compression is going, air will blow out through the carburetor (intake valve), exhaust pipe (exhaust valve), valve cover (piston rings), radiator (head gasket)
Disconnect any vacuum lines from the intake and plug that port, power brake booster, automatic transmission, vacuum reservoir
The intake is divided into two plenums, one plenum feeds cylinders 2-5-4-8, the other feeds 2-6-3-7. A vacuum leak at one intake runner will lean out and effect all cylinders connected to that plenum. One side of the carburetor not working will affect the 4 cylinders that side feeds. If you have a burnt, warped or stuck intake valve on number 6 cylinder the compression being forced back up through the intake will kill the vacuum drawing fuel to the other 3 cylinders on that side of the intake plenum
Remove the radiator cap and valve cover fill cap, then pull number 6 plug and connect a air source to see where the compression is going, air will blow out through the carburetor (intake valve), exhaust pipe (exhaust valve), valve cover (piston rings), radiator (head gasket)
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