I swear when it gets cold out my car runs kinda crap. Cool weather is fine, but this 40 degree stuff we had tonight made it run kinda rough. Not bad necessarily, but it just seems like it runs better when it's 80-90 degrees outside.

So i was wondering if maybe this just means I have a calibration problem and this makes it more obvious... or do you guys have different tunes/jettings/idle mixture settings or whatever in the winter time?

 

carbs cant retune themselves for changes in air temp. colder air means more fuel is needed. its not uncommon for carb guys to run a set of winter (bigger) jets and a set of summer (smaller) jets.

 

Yeah, a jet size or two can help if you were a little lean to begin with. Just don't over-do it. If you're moving 4-5 jet sizes something's not right.

 

i just swap the secondary jets to the primaries and put the 2 sizes bigger jets in the secondaries for cold weather. works out pretty good for me

 

I've never messed with the jets in this carb yet so it's still rollin on the factory supplied jets, which are 67/73. I know at least some had a 67/70 setups and so forth which is a lot closer to the spread mentioned above. Am I right to assume that taking the primaries from 67 to 73 is a bit too big of a jump?

Anyway thanks for the responses, I was just wondering if my tune was just a lot farther out than I realized. I never really hear about people rejetting their carbs for winter, but I didn't grow up in hot rod circles either. So I'm not sure what's normal and what isn't in a lot of ways.

 

well i should mention that im running 68/72. so its not that big of a jump for me, if temps drop ill switch to the 72/76 and run a lil rich for a month or so (temps dont drop that much in tx for very long)