I live in Alberta and have been driving my FB since december (winter beater got stolen). It's got 170,000km, racing beat air cleaner, RB header & presilencer ($20 wrecker score) and no cats. When it was real cold (-10 celsius, or 10 F) it pulled harder above 4000rpm. Now that the weather has warmed up it doesn't pull as strong. Any suggestions?? Jetting?? thanks

 

Also, I picked up a used 12a for 40 bucks, it turns and apparently ran (15 years ago, been under a bench in a garage). I am going to use it as a rebuild core, going half-bridge. How can I tell what year it is? mine is an 84 and running well.

 

actually colder air is dense, and thus the denser air increases volumetric efficiency and allows the engine to run smoother at times and run a bit quicker and rev happier.

 

It pulled harder when it was cold because it could take the extra petrol. Dense air means u can fit more of it into a space and hence more petrol. Changes your jetts for sure.