Carb losing gas overnight, flat spot

[ChrisinAZ]

I'm having problems with the carb (Ford) on my '64 Tbird. First, it seems to be losing the gas in the float bowls overnight (admittedly I'm in AZ so it's warm). So in the morning it's churn, churn, churn to get started. Second, the carb has been rebuilt with a kit but still has a flat spot on accelleration; it idles fine and picks up OK with light throttle but when driving it hesitates badly when pulling away from a stop. Sparkplugs are OK, compression is OK. Any ideas on what to try next?

 

[boaterbob]

Could try this forum
Ed's Carburetor Forum. Carbs rule!!!!

 

[Watermelon Jack]

How old is the fuel pump? That could be your problem.

 

[64tbirdtampa]

You need to rebuild the carb. Check your carb manufacture and order a rebuild kit.
Float or diaphragm or gasket leaking.

 

[ChrisinAZ]

Thanks for suggestions. Carb has just been rebuilt but will check it's done OK. Will check fuel pump is not letting gas leak back into tank. One post on the carb. forum suggested (thanks boaterbob) suggests it could just be modern gas evaporating... Oh well, as as long as the Tbird starts eventually.

 

[64tbirdtampa]

Cab loosing gas overnight, 3 places it can go.

Hi, me again. Only 3 places it can go. Evaporation like someone mentioned, draining back into the tank or draining into the intake manifold or fuel pump
Leaking into the oil pan. Check your oil, does it smell like raw gas!

 

[ChrisinAZ]

Thanks for all the feedback. It looks like starting, it's mostly evap: it's hitting the mid 80s here; following the starting procedure in the handbook and churning a few times gets it going.

Still got that carburetor stumble, worse when it's cold. The carburetor forum notes it's important to have the accelerator pump linkage pre-loaded with the throttles shut, no backlash. I've got it fairly tight but it still hiccups pulling away from a stop; more ideas please!!

 

[JChambers685]

Is the thermostatic spring in the choke functional? If you're stumbling from a stop you may have a busted spring which is causing the butterfly to be wide open (causing you to run real lean at idle or low cruising speeds).

 

[boaterbob]

How about the power valve in the carb? Also is timing set correct you could try advancing it a bit and see what happens. Did it do all this before the carb rebuild? No vacuum leaks?