Holly carb surging

Not sure why but think it might be a leaking needle seat. Sat for a year and had to tighten up the acc pump and replace manifold gasket. Now this, any other ideas?

How is your float level ? If your needle and seat were leaking or sticking the float level would be too high . Pull the sight plug and check it. Sometimes a power valve will cause this.

Gus

Checked while running and no fuel leaking down Ventura’s, only does it after complete warm up. I have another carb I’ll stick on to try this week sometime, have to use van tomorrow. One other thing, if I hold pedal down a little more in gear at a stop light it evens out. Maybe trash in idle circuit.?

Is it possible it's a gas problem? Maybe the carb is too hot, and the gas is boiling.

I'm going with year old gas

Mine is doing this. Only after hot or heat soaked. Perfect otherwise. Thinking I might’ve gotten a load of winter gas. Picked up some race gas to blend in last week. Vapor pressure of the race stuff is 6 psi. Winter blend can be as high as 14 psi I was told. Yikes!

Almost empty filled it up same, did same after fill up 2 months ago

Surging at idle, cruise?

I am just going to toss something out there, because your symptoms sound a little like what mine were.

I had a nearly brand new fuel filter on (mech fuel pump, 3/8 barb metal-housing filter), so I didn't think that was my problem. But for kicks, I took it off and I discovered that all I had left was the outer housing and a metal inner part, all of the paper filter part was gone, and the residue or whatever presumably in my carb. I didn't find any big pieces. I am pretty sure the filter was not like that when I put it on, or I would have heard it rattling.

Anyway, I disassembled the carb, blew out all the passages the best I could with carb cleaner and compressed air, and it seems to be fine now.

Greg

The Original filter that screws into bowl (1987) I’ll check it out. I surges at idle about 600, if I raise a little in gear it kinda evens out. Better today from short drive. Could very well be trash in there

have you checked for vacuum leaks or tried adjusting the idle mixture ?

I will this weekend when I have more time, busy doing the Dentist office this week (big project)