[PBCOUG]

My 68 has been timed perfectly since the top end rebuild, I use the highest octane fuel and can punch it without any pinging at all. I'm in the Bay area (n. ca) and all of a sudden the coug is pinging. Is it the winter fuel blend they use here? or the drop in temp , around 50/55, really not that cold.
Any Ideas. Thanks
PBCOUG

 

[lbesq]

thinking winter blend

 

[xr7g428]

Try a different gas station. If you got 87 octane instead of the 91 or 93 you paid for, you get that exact result. It can be a mistake, but with new cars having knock sensors, most people will never know the difference.

 

[PBCOUG]

I got chevron fuel the other day and after about a quarter tank the pinging seems to be gone. the previous tank full was shell, must be a bad batch or chevron is better gas.

 

[Bad69cat]

Hard telling - they have so many gas blends out there anymore - especially in you kneck of the woods! (part of the high gas price!) I'd throw in a can of booster if it starts giving you trouble, or back off the timing a tweak. I don't have to deal with altitude to much around here, but you may need to richen up the carb a tweak if you elevate often.