If I set the idle mixture using a vacuum guage, (talking about a Holley 650DP), then change the jet sizes up a bit, do I have to set the idle mixture again?

I have one side of the motor running hottwer than the other, so i'll adjust the idle mixture, but then if it is still too lean, I'll have to change the jets. Just wondering if i have to do the idle mixture again.

My passenger side CAT was glowing red under the shield, the driver's side wasn't.

 

seems like you need a new Cat on the pass side

 

The CAT is brand new.

 

Look for a bad spark plug wire on that side of the motor.

 

The jets in a holley dp carb have nothing to do with the idle mixture. When the throttle plates are closed you draw fuel from the idle system. When the throttle plates are opened you draw fuel from the jets. You should not have to play with your mixture after changing jets.

 

The CAT maybe brand new but somewhere you have a rich condition that is what causes a CAT to glow red and it will also cause it to go bad.

 

Lean condition will make it run richer. I jetted up the carbs and richened the idle mixture, and the glowing Cat went away.

 

If it's lean, then how can it be rich??

 

HUH?

 

Heheh, you'd think I was drinking. I meant that the lean condition would make it run "hotter."

Sorry for the confusion. Thanks for all the help guys.

BTW, it's running full with dual 3" and UltraFlows, and they blow the Flowmasters out of the water. They sound awesome.