Could it be the gas?

[Anonymous]

Hey yall,
Just a quick question. I drove my mustang (66 w/ 81 200) for about a 1 hr. trip yesterday. My dad had filled the tank on hi test. I was running low on gas yesterday so I stopped and put about 5 bucks in low grade. I didn't notice any difference until I got home. It is running real rough and when in gear at the idle it vibrates alot. I just put a Duraspark in and set the timing running hi-test. I'll check all my connections, plug wires, etc. The engine is also leaking some oil but I think its the oil pan.
Do youall think its fuel related? Could my oil problem be related. If it is because of gas, setting the timing again would fix it right, I'm running about 14 deg. adv.
Thanks
Paul

 

[CobraSix]

Could be...but not like you expect.

The octane generally is not going to effect the idle qualities of the car. It's going to effect how the engine behaves really at High RPM and under high load.

You could have gotten bad gas from a station. Not sure where you went, but that's why I never go to mom and pop gas stations. I know, Im' supporting the oil giant companies...but I know I get good gas that hasn't been sitting in a storage tank forever.

Double check timing and everything though before you blame the gas. I once had my idle screw some how open up by itself from driving it for 30 minutes.

Slade

 

[Lazy JW]

I agree with Slade, the octane rating of the fuel probably won't cause this problem, but water in the gas sure can. So can an ignition problem. It's time to go through the basic tuneup stuff, inspect the plugs, wires, etc. Also check for vacuum leaks (loose carb, vacuum lines). If you still suspect the fuel, put some gas line antifreeze in the tank and change your fuel filter. This won't hurt to do anyway. Good luck,
Joe

 

[BIGREDRASA]

If you ran it almost dry, you may have picked up sludge off the bottom of the gas tank. Check/change the fuel filter.