[zreg]

I have a 1973 Mustang Convertible and it starts and runs fairly well. I just bought the car and it needs some work, but it is a running project car. I put 93 Octane unleaded in the car and am concerned that I may need to to perform some modifications to run this fuel. Right now, the car hesitates when accelerated from a stop and also from low speeds, but I have not floored the engine. The exhaust is clear, but after driving on the highway for 30 minutes I noted some black soot on the rear bumper, so I think the engine is running rich. I plan on replacing the plugs and points, but I am not sure if I can use 93 octane unleaded. The engine is a 351 4V (4Barrel). I don't think the engine has been modified. Any tips would be greatly appreciated. Thanks

[1slo5.0]

Sounds like you need a tune up and carburetor rebuild. 93 octane will be fine in that engine. You could probably get away with 89 octane.

[Twist 2 Go]

also ck the dist. vacuum advance diapragm and make sure it's working correctly.

[68 Coop]

I think the octane grade is OK, but it sounds like you might re-jet your carb. What size jets and needles are you running now?

[My67_fastback]

dont run higher octane if u dont need it. its highly possile that the engine is due for a rebuild, so the compression has lowered, causing the engine not to like that 93 octane fuel you're using. do a compression test.

[Clutch]

I'd also say to give it an "Italian Tune-up"

You know, where you go out to the highway and get into it a little bit. Helps flush out residual gas and other junk from the intake planes before they turn into power robbers.

I also agree, regardless, a tune up is most definatly in order. No matter what anyone tells me when I buy a car (except brand new ), the first thing I do is a tune up.

Cleaning and rebuliding the carb is another plus.