I am having surging power at half to wide open throttle.

I replaced my fuel pump filter yesterday and I am still having the problem.

1965 FB, Stock A code, Autolite 4100, Pertronix ignition, New Stock Distributor, Hi Po Manifold, Magna Flow Exhaust.

I tried the timing from 6 -11 degress and the surging power isstill there. I can not find aVacuum leak?

Any help would be appreciated.

My Initial thought was Vacumm Leak, then Fuel filter and now I am wondering if it could be my floats on the Carb?

 

I had a similar problem, and tried the same things as you did. Ended up pulling the top off my carb, finding all sorts of brown gunk in there. But I never had anything show in the clear fuel filter. After I cleaned it out, she ran like new.

 

If your saying its surging/bucking at half to full throttle, it could be anything. Float is always possible but before you go there, Whats the condition of the plugs, wires, cap, rotorand coil? what's the fuel pump pressure and volume? ( a lot of "fuel problems" turn out to be electrical)

 

+1

 

definitely check the plugs and wires

 

Did you disconnect and plug the vacuum advance when you varied the timing?

Did you check that the vacuum advance is working?

If the advance is fine I'd rebuild the carburetor. A 4100 is a piece of cake. Buy a quality kit.
Just be sure not to lose the tiny check ball in the secondary vacuum passage. They do not come in the kits.

 

Thanks for all the inputs.

The carb was rebuilt a year and a half ago, new plugs, wires, cap and rotor. I plugged the vac advance when I set the timing and vac advance is working properly, or as best as I can tell.

The fuel pump is only a few years old. I am still stumped at what it could be.

 

Regardless of when things are changed, things go bad. So you have a couple of options, take it to a shop and have them diagnose it for 50-100 bucks or do some simple troubleshooting and see if you can save a few bucks. Checking the fuel pump volume andpressure is free and simple, checking/replacing the spark plugs is simple, same for wires, cap, rotor, etc..
people tend to overthink things. Go to the most obvious thing first and prove or disprove it.
my 2 cents worth.

 

Knowing it was either electrical or gas, Iwent through the following steps...Checked timing, checked the dist cap and each wire. The cap looked like it had tracking between the terminals,so I changed it. It still surged. Then went to checking for a vac leak, did not find one, nor did iexpect to since it had been running great until then. I switched to the gas supply, 1st checking my fuel filter. It is a clear one, and had notheing in it, but I changed it anyway. It still surged. I though for sure it had to be mny fuel pump at this point, so I changed it....still surged. At the suggestion of someone on this forum, I checked the inside of my carb, and he was right. it was full of crap. I have no idea how it got there, since the filter was clean. So I took it all apart, sprayed carb cleaner through all of the jets and nozzlesand she ran great again.

 

good advice and good methodolgy!