will winter fuel "ping"?

[Hipo65]

Just as the title says. I've noticed over the last 2 fuel ups @ to diffrent stations that now out of the blue the ol 273 seems to wanna hesitate a bit & from low engjne speed if you hammer it it pings now! Wtf?! This car has NEVER pinged in the last almost 2 years of being rebuilt! Timing hasn't changed same stock afb I'm open for ideas. idles fine no miss that i can tell at all. not using oil or coolant i really wanna blame the fuel but @ two diffrent stations having sub par 91?!? Thanks people.

 

[70aarcuda]

winter time good air

 

[Darter6]

Yes!! I hate when they go to "Winter Blend" around here.My stuff runs terrible. The old car and truck exhaust pipes also have sooty tail pipes during this period. Even the wifes PT stumbles and farts during the "Winter Blend" season.

 

[Hipo65]

Ok so I'm not crazy then. well sorta its just weird cuz last winter i know i got gas winter before & she has never pinged before until saturday.

 

[abodyjoe]

Maybe it's lean in the cooler air.

 

[kursplat]

winter blend smells like crap and makes my car idle 50 to 100 rpm higher. doesn't matter what the weather is. last week it was 80' here. couple of days ago ~75 and muggy, then rain. strangely, it doesn't ping any easier, but I run 93 octane all the time.
bone stock 74' 318-2bl

 

[Hipo65]

It does seem to run lean as of late,& the cooler air really makes er run hard. but around here its abnormaly warm 50's & lower 60's you can't ask for better weather & the car likes the cooler air. I've taken carb apart & cleaned it (nothen in there just checken. timing is rite where i left it (10° btdc) i really don't know what else it could be. the pertronix pick ups eather work or they don't correct? Timing lkte says its fine. just getten on my nerves cuz this car runs great always has,now this out of left feild. If it were intake sucken air its not internal cuz not using any oil ill check out side with carb cleaner tonight.