Air in fuel system

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christie656746

Junior Member
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Aug 19, 2023
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Location
Salida, Co
First Name
Chase
Truck Year
1985
Truck Model
K20 suburban
Engine Size
350
When the filter becomes dry the pressure gauge right before the carb loses some pressure but not all (set to 5psi, will drop as low as 3) And it never jumps even if the rpms go up and down. Motor has 4000ish miles, cam has about 3000. Put sealall around all connections this morning to eliminate the possibility of air leaks. Nothing. Going to pull pushrod tomorrow and measure it. Then my next guess would be putting a dial on it to see if I messed up the pushrod lobe.
 

Ricko1966

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Joined
Apr 11, 2017
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Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Checking pushrod movement isn't real scientific,it moves about 7/16 inch take the plate off push the pushrod up with your finger dist hotwire disconnected crank the starter,the push rod will move a bunch or barely move,they don't just go a little flat. If it moves a bunch measure your pushrod. How much restriction are you using on your return it should be significant like .060 .I'll try to find a legitimate measurement for you. Found a thread on a different forumn,as measured using numbered drill bits .057 so .060 close enough. Currently I'm just running with my return line pinched to where my truck likes it best. I got a lawn mower fuel shut off valve, thanks @bucket , that I have not Installed yet,that way I can bypass however much fuel I need to .
 
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