Running rough at 1/2 throttle

[jkcrosson]

I went for a 50 mile ride today in my car. About 15 miles into the ride, I noticed that the car was missing when I went past 1/2 throttle. As the ride progressed, the running got worse.

I have checked for:
Points gap .021
Points Spark white/blue
Timing ok
no loose wires
Drained and emptied carburetor bowl for possible water in Carb.

The car idles fine and runs fine down to the 1/2 throttle point but it goes south after that point. It is worth noting that it had been parked for 3-4 weeks in Alabama heat and humidity. Not a good thing is my gas tank is now sitting between E and 1/4 of a tank closer to E. I think I'm being haunted by ethanol gas. Any ideas.

 

[jw hash]

I just had the same problem and I check the compression and after three carburetors three distributors and three coils, I pulled the motor to change it out with another motor I had. now as I`m taking the first motor apart and I find that my intake manifold gasket between 3&4 was leaking on the bottom. it would start and run fine just fell on it face after half throttle. another thing I had noticed when I pulled and check my plugs I was running to lean. they were real clean

 

[Rex_A_Lott]

Where was the GAV? Did you open it to see if it helped/hurt? Did you close it to see if it helped?hurt?
How about the spark? Was it all the way down? Half way down? Did it get better or worse if you retarded it?
Worse under load? Smooth out on the flat?
You could help yourself by doing all this before you ever stop, so that you will have an idea of a direction to go looking.
IMHO the ethanol wont cause the problems you describe...but it can cause others.
I really think you dont have as much gas as you think you do.But thats just a SWAG.
Fill it up and start over.Good Luck

 

[jkcrosson]

Rex,
I normally run my GAV about 1/4 open and spark about 2/3 down. I opened the GAV up to a full turn open with minimal improvement. I retarded and advanced the spark with it never clearing up. It was worse under a load and smoothed out but not completely on the flats. My gas gauge still has almost 1/4 when it reads E. I do agree on the filling up the tank. I also plan on checking for intake leaks tomorrow.
Thanks