87 vs 89 octane

[travis565]

I have a chevy 350 in my jeep and I've been having problems with it trying to stall when I slow down or go around turns and sputtering on acceleration breaking up in wot. Well I changed plugs wires cap and rotor rebuilt carb and adjusted timing. Nothing seemed to fix the problem. I know I'm running a lil lean which as soon as I make it to the performance store that will be fixed with new jets. The guy that had the jeep before me jetted it way down. So to get to the point nothing seemed to make it run right. I just came to grips with buying a new carb. So today I decided to put 89 in it instead of 87 and man it was like magic to my engine. No stalls decreased breakup no sputtering. Runs like a champ. Kinda weird I've heard of it making a lil difference but this thing runs completely different.
I have the timing set at 8 btdc with the vac advance hooked above the throttle plate rather that at full vacuum at idle. I may bump it up to 10 to see a bigger difference. Anyone else have this drastic of a change when switching fuels?

 

[Cheepjeep85]

i've never had the kind of difference you are describing. the most i have ever seen was it stopped the valves from rattling.

 

[jeepy]

Sounds to me like your float was set too low. Or perhaps you just had some bad gasoline.
Like CheapJeep was referring to, the 89 is just going to allow you to advance the timing a little more.

 

[BusaDave9]

Could it be quality of gas instead of octane rating? Did you get the 89 at a different gas station?

 

[priceg]

Just a note, the method that petroleum company's use to rate octane can vary as much as 2 points.

 

[travis565]

Yea it was a different gas station. That could def be it. I reset the floats to a lil higher. I have the unadjustable floats but I just bent the tabs a lil to where the top of the float was parallel to the bowl. I'm going to change jets today but I'll keep 89 in it for sure.