Idle speed

[JOE BYRNE]

My books say that my idle on my 73 (4 speed) should be at 900. It seems to idle fine at 900 and has been in that area for the last two years. My fuel/mix settings have no effect at that speed so I set it down to 600 and made the proper adjustments. Every carb place that made contact with me said the 900 was to high???

Back to 900 or 650 to 700....this is a 73 with no emissions on it.

 

[wishuwerehere82]

My book says 900 for manual transmission.
Did the idle screw adjustment at lower speeds work the way they were supposed to? Because if they made a difference in the speed at 600, then it probably will not run as rich as it was at 900.

 

[JOE BYRNE]

Pete

I e-mailed you re the idle/mix. I set it at just under 700 and it's fine. After palying with the fuel/mix yesterday It runs better than ever...check your email

 

[wishuwerehere82]

Joe,

Sorry, I hadn't checked it this afternoon. You will get it right after you road test it and blow the carbon out.

 

[JOE BYRNE]

I stuck it in the email

 

[wishuwerehere82]

Now that it's adjusted, bring it back to 900 and it should be all well again.

 

[The73vetteman]

My book says 900 for the 4 speed (maybe we're using the same book) but I've always thought that a little high. I set at at around 800 - 850 and it idles nicely.

I do notice that the idle is very sensitive to air temp. On a hot summer day it will be over 900 whereas this weekend it was under 800. I'm running a 650 Holley, which I believe is sensitive to such things.

I'd be interested in knowing more about the carb you're using and your idle settings. Carburation is more art than science (or so it often seems) and there's always something to be learnt.

 

[JOE BYRNE]

I sent a few messages out to carb shops Sunday about not being able to set my fuel mix screws. They were not making any differance when adjusting because my idle was to high. Every carb shop told me I was insane running at 900 on the idle. All three of my books say 900. After trying to lean it out I set it at 650 tonight. Idles a little lower but nice. I might keep it there for a while. Seems like 68 to 72 was a bit lower and then in 73 went up. Possibly it was because of all of the emissions? I dont have any on mine so I set it down a bit for the time being. Im running a rebuilt Rochester Q Jet on an Eldebrock manifold, heads and headers.