Where do I start?

SBC 350, mild cam (thumper), 300hp Petronix Ignition, 2 Rochester 2 g's 700r Transmission.
Problem; running down the road at interstate speed 55-70 mph OD on. Car will load up and sputter every couple of minutes. Smell of gas then follows. When shifted out of OD into third gear rpm's up,car seems to run fine. Waiting now for engine to cool to pull the plugs to see if there is any visible crap on the electrodes.
Any other suggestions?

 

fuel pressure?

 

May be too much fuel pressure. The higher RPM's out of overdrive may be using the extra fuel, which is why it runs better and you don't get the smell of gas. I ran 3 deuces with a fuel pressure of 4 lbs. Too much and the Rochesters would be spitting out fuel.

 

Inlet needle valve not closing properly, too high of fuel pressure, float level too high or choke closing?

Sounds somewhat borderline, as at higher rpms, the engine seems to be able to burn all the fuel, but not at lower rpms in od.

I'd bet your plugs are black and maybe starting to foul.

 

what RPM on the engine in OD at 55-70 MPH?Maybe the jets are too rich.Is the car a stick or automatic?

 

Transmission is a 700R Auto Overdrive. Should be cool now. Going out to take a visual of the plugs.

 

I was gonna say check the plugs... It sounds like a bad coil or pickup.... Are you sure all your connections are solid? grounds ect....

 

I think Wylie is on the right track---RPM falls off too far and too much gas.

 

rear end ratio ?

rpm on interstate ?

 

Just pulled plugs and they look fine. Backed fuel pressure off to 3 lbs. (from 4 lbs.) Going to wait until tomorrow for the test run. Rush hour traffic here in Indy is a bitch. Got a list of all the recommendations here on this thread.
Thanks.

 

This sounds like it. Too much fuel -- either pressure or something else.

 

Hey man were you at the rumble this year? I looked for you and your car and did not see you on Saturday. Is it running that bad? Sounds fuel related to me.

Vic (Sedanman)

 

I had "similar" problems. Changed the fuel filter, changed the plugs, switched from a holley to an edelbrock, good fuel pressure (set to 3 psi with regulator). The carb seemed to do the trick and thought I had it licked. Then after a week started having the same issues. Just acted like it was starving for gas.

This weekend at BTTF's after driving it 250 to get there, it quit. No spark so I changed the coil (HEI). Started right up and purr's like a kitten and no issues since. It runs better than when I thought it was running good before.

My guess is intermittent coil problems and it couldn't burn the fuel being pumped into the cylinders...

 

Didn't make the Rumble Vic. Family thing came up. Spent the week in Florida with my daughter/son in law and granddaughters. A special treat was one granddaughter from California that surprised me. I won't miss next year.