My problems continue I can get the engine to run for a few min but then fuel pours out of the carb is the Carb shot any help would be great I don't know much about carbs. I'm running a SBC 350 with an AFB 650 carb I'm thinking of replacing it with an Edelbrock 600 1406

 

if you put a carb on a vehicle that has a fuel injection fuel pump on it the gas will waterfall out of that thing due to being way to high on fuel pressure. if this carb has worked fine in the past and is leaking out of the accelerator pump, gasket, or other moving parts then yeah probably just need a rebuild or a new carb

 

Engine a 78 sbc 350 with a mechanical fuel pumpI bought the a Carb used it a 650 AFB…if I run the engine at high Rpm runs fine as soon as it idle it fun for 20-30 seconds then fuel pours out both sides

 

Float level is too high and needs to be adjusted.

If it has a brass float, it might have a hole in it, and sank.

If it is a composite float, it might be saturated with fuel, and sank.

Needle & seat might be stuck open.

 

Thanks

 

We still dont know what vehicle this engine is in and if the original fuel delivery system is still intact. just because the engine has a mechanical pump does not mean the electric pump is not still in the tank and operating. If all the fuel lines and return lines have not been changed and configured for a mechanical pump this could still be an issue. i would suggest putting a fuel pressure gauge inline to the carb to just be sure the carb is not being over pressured and to double check that there is a return line to the tank and all vents are operating. And yes typically float level would be the first culprit if this where not an engine swap.

 

Took the carb off and put an old Holly on engine ran fine. Adjusted the floats on the AFB put it back on same fuel problem. How to you check and adjust needle Valve?

 

Is it possible to clean or should I just really replace it?

 

There is no adjustment to the needle and seat. Adjusting float level takes care of it. Might have a deformed needle tip or there might be crud stuck in the seat. In my opinion, the Holley is a better choice than the Carter AFB. The aluminum corrodes over time and leaves deposits in the passages. Back in the late 60's early 70's the "Aluminum Four Barrel" was a very popular carb. Holley is a good reliable carb, always has been, just need some "tinkering" now and then

 

Thanks I will stick with the Holly the final question before I move onto the suspension is timing…it's set to zero right know what would be the usual timing 8-10 BTDC? How to your determine what's best?