Brake and carb help

[Dz1331]

First time to post. So thks in advanced for any help.

Ok have a problem. I have power brakes. Replaced my master cylinder bleed it and did a good bleed on all 4 corners. I have real good pedal when the truck is off, but when I start it and put it in gear then push the brake pedal it goes to the floor. Master cylinder never loses fluid. What next?

Also next problem bought the truck has a crate motor runs real smooth but when I kill it and come back a few days later it will not crank. Put a little gas in the carb and cracks right up and runs smooth again. Original carb. From what I read y'all know everything about these trucks. Need a little help.

[kcsa75]

Can't help with your issues, but wanted to pop in to Welcome you aboard.

[motorcritter]

Carb issue sounds like leaky bowl plugs in a QuadraJet, especially if that carb is not a brand new one, just the old one swapped over to the new crate motor. The brake issue may be a master cylinder pushrod adjustment issue.

[PatrickGMC70]

Carb: it won't "crank" or it cranks, but won't start?

If it starts when you add fuel, it could be that your fuel is evaporating out of the bowl and it takes the pump a few seconds to refill it. It could also be that your fuel filter doesn't have a check ball in it and the fuel is draining out of the carb and back into the fuel lines. They make fuel filers with a little check ball in them to keep the fuel from draining out of the carb.

Be gentle with that fuel filter fitting. Get a 5/8 line wrench and a 1" wrench to get it off. Remember that carb is made of pot metal and those threads have 40 years' worth of wear on them. Those threads are easy to booger up. Don't ask how I know.