So im thinking its the just corvette based motor versions right or do any of our carb,tbi,tpi engine use premium gas?

 

I dont know about anyone elses experience, but I can say without a doubt that my 305 runs like a dog unless I use 93 octane gas. I get knocks, and pings when my kid gets cheap and puts in 86 octane. Most cars will burn just about anything, but how well they will burn it is a different story.

 

My TPI 350 runs perfectly fine on 87.

I've tried 93 for a few months. Even reset the ECM before I switched. ade zero difference in driving, performance or gas mileage. The only change is made, was making my wallet lighter!

 

I wish I was that lucky. This car is so picky that even a different brand of gas makes what little performance it has noticeable. Even the exhaust tone changes with the lower grade gas, and the car will run just a tad hot side. This poor old dog has 157,000 on it though, so Im sure there are many things going on that Id rather not know about.

 

93 is not needed in a low CR tbi 305...

if such is the case, you have other issues going on.

check the timing/plugs...

 

I dont sweat it too much, this thing is coming out real soon. I know this motor is pretty well fried, low oil pressure, clouds of blue smoke at start-up, that great smell of unburned fuel. Dont get me wrong, the car will run on 86 octane, it just doesnt run nearly as well as it does with 93. Its also not my imagination. I put 86 octane in it about 2 months ago by mistake, and made a run up north. On the big hill on 141 it fell flat on its face. After running around and burning through that tank, I refilled with 93, and on that same hill it was fine. My caddy is the same way, anything but 93, and its runs like there is an anchor attached to it.

 

The ones that ping when you climb a hill or mash the accelerator pedal

 

My 305 tbi is fine with 87. The only time I had pinging issues was when my knock sensor was bad.