General Category > Quadrajet Carb Talk and Tips

I think I'm running too lean causing high hydrocarbons and low CO's.

<< < (2/3) > >>

Cliff Ruggles:
Not exactly sure why you are focused on bypass air.  I'd do an idle "tip-in" test first, to see if richening it up helps as the engine will smooth our and idle speed may increase slightly at the same time. 

Taking away bypass air will alter the throttle angle at any given idle speed, and expose more transfer slot.  Might even uncovered a ported source and make it act like a manifold vacuum source, and too much and you may see "nozzle drip". 

I usually don't mess with bypass air unless I've got nozzle drip and need to add some, or throttle angle is high enough it's uncovering the ported source for the vacuum advance.

It's always a case by case thing, but for sure if idle fuel to the mixture screws is inadequate I correct that issue first........Cliff

Terry Petty:
OK so how do I do an idle "tip in" test?  Do you mean choke it a little? 

If it smooths out and idles faster, what does that mean?

How do I know if I'm not getting enough idle fuel supply to the mixture screws? 

I will follow your instructions.

Terry Petty:
So I'm looking at another post and you talk about opening up the idle tubes .002".  Is there a special drill bit for that?  Do I need to remove the tube and collar to open it up? OR can you sell me the right idle tubes?

Cliff Ruggles:
A "tip in" test can be done to determine if the idle is too lean or part throttle. 

For an idle test get the engine fully warmed up, heat soaked and adjust the idle mixture screws for best idle quality.  "Tip in" the choke flap or richen things up by gently placing your hand over the choke housing, not enough to choke it out, just enough to fatten things up and see how it responds.  If it speeds up/smooths out it needs more idle fuel......Cliff

Terry Petty:
It speeds up and smooths out.

Navigation

[0] Message Index

[#] Next page

[*] Previous page