305 surging at Highway speed only

[geezer#99]

I guess you’ve never heard the old saying!
Timing first, carb second.

Set your timing and you might not need to fiddle with the carb.

[68 P.O.S.]

Originally Posted by geezer#99

I guess you’ve never heard the old saying!
Timing first, carb second.

Set your timing and you might not need to fiddle with the carb.

True, 90% of carburetor problems are timing

[A1971Blazer]

Originally Posted by Wrenchbender Ret

The sock on the end of the fuel intake tube in the tank is plugged up. When you replace the sending unit you will solve the problem.

George

This ^^^^^
Carb adjustment, timing etc..... ain't gonna change just by pulling off the road and waiting a few minutes....

[tutone]

UPDATE
Today I replaced the sending unit, line to the fuel pump, added a regulator and a new fuel filter. Tested for leaks an threw a light on it 8 degrees timing so rather than change that, I went with it like that.
I expected to see a big change, and I did. Now it runs worse than ever. It was at highway speeds, and now it is in all rpm ranges.
I suspect this is a fuel problem and I will explain why. I asked for a metal filter , but all they had was a clear fram filter. With the regulator set on 5 psi, the filter is dry as if it has hardly any flow. I may be off base, but before I do anything else, the fuel pump gets swapped and I will report back.
Next day. New fuel pump. No change. Removing regulator and trying that.
Regulator removed. Fuel system completely new and I'm back at my exact syptoms that I had to begin with. I guess as far as that goes, I at least have a working fuel guage on a truck I can't go anywhere in.

[tutone]

Well after throwing money at it ,I have found the problem after all.
I do believe my torque converter is slipping in 4th gear. The rpms go up and down methodically. I did a hard acceleration test from 0-60 mph and it was perfect. It never hit 4th but when it did, the engine relaxed and the surging began. Thanks to all that helped me in the trouble shooting process. I don't know yet what I am going to do, but there will never be a 700 r4 back in this heap as long as I own it.

[tutone]

I kept working on this problem even after my last post and decided to swap some items to find out if it really was the torque converter. Turns out, luckily, it isn't. I swapped a different distributor/ cap/ and rotor. Same old surge.
Double checked for a line kink,/ none. Finally I took the edelbrock off the 55 and put it on the truck. Runs like a dream. Something in that carb has gone wrong. I plan to rebuild it and put it back on and try it. I want to drive it to the C10 Nationals in Nashville in a couple of weeks and I need it to be dependable. Thanks to every one who helped out