What's the best bet, a cold or a warm engine (I've read that the latter will provide a false reading)?

JamesC

 

With a completely stock engine, setting it warm is a safe bet.

With a modified engine, might as well set it cold so you get what works well.

 

Mine is set up for the cold weather right now. I figured when things warm up I'll switch back to operating temperature.

 

Fast idle setting only matter when the choke is on, which means the engine is cold when it operates.

Guess which way I'm leaning on this issue?

I set it so it's in the ballpark and then tweak the setting a little each time I do an overnight-cold start. Couple days of that and you'll zero in on where it feels comfortable.

 

Yes, It's two seperate adjustments.

Let's assume we are only talking about cold fast idle. In order to set it, idle mixture, idle speed and A/C stepper (if equipped) must be dialled in perfectly while engine is warm. Make sure your choke heater, whichever method your engine is using, is working properly.

Next, when the engine is cold, you have to adjust both the angle of the choke valve and fast idle at the same time. And when I say cold, I mean overnight, not just down to where the temp guage is all the way to the left. Then over the course of the next few cold mornings, you can fine tune your fast idle to whereever you are happy with it.

 

Hmm, mine was set 2800 when the carb was rebuilt. All I did was dial down the screw adjustment on near the choke to pull the fast idle down to around 2200. Kicker is currently set to about 1400, something I still need to dial back down.

I want to bring the fast idle down farther, 1800 or so, but I'm afraid I'll just stall out. I know on cold mornings if I start the car and kick down from high idle to the second idle which is currently 1800rpm or so, the car stalls out.