High idle

Can someone school me on adjusting idle speed? Got a 240 with (I think) a holly 200 carb?

I don't know that specific carb, but high idle is rarely an adjustment issue -- unless you've done a rebuild and/or installing a new carb. Much more likely to be a vacuum leak or a sticky throttle cable.

Before doing any adjusting, spray carb cleaner around the base of the carb and intake manifold to see if idle changes, identifying a vac leak. Check vacuum hoses are properly seated at both ends and in good condition with no cracks. Make sure the throttle closes completely. Just my two centavos.

By the way, my 240 was sporting a Holley 1940, but they also came with the Autolite 1100. Adjustment is essentially the same for both.

The idle screw (left) on the throttle arm goes in or out to speed up or slow down the idle by pressing against the throttle. The idle air screw, bottom right, controls the amount of air at idle. You want to get the "leanest, best idle" Typically you screw it in all the way, then back it out 1 1/2 turns. Then you do very small adjustments to get the fastest idle with the least amount of air. "in" is less air.





Another pic of my Holley 1940. Showing the spark control valve:

that's awesome. going to try this weekend. Thank you!

so I should start by screwing both the speed and air screws in all the way, back out both screw 1 1/2 turns, start the van, and adjust both to desired idle? How do I know if it is as lean as possible?

Again, it's unlikely you need to adjust these. More likely it's a vacuum leak or something else going on.

On the idle air screw, it's all the way in, then back out 1 1/2 turns and adjust from there. The idle should speed up and slow down as you make small adjustments. You want the fastest idle you can get with the screw in. You will hear a definite sweet spot.

For the idle screw on the throttle, it's just in the middle of its range to start. Once you get the idle air right, then adjust the one on the throttle.

Of course, you only make adjustments when the engine is fully warmed up and the choke is off. And, after you are sure there are no vacuum leaks!!!

okay - so back to the vacuum leaks then - So I spary carb cleaner around the car, hoses, etc, and listen for the idle to increase? If it's a hose, replace it. If it's the base of the carb then fasten it tighter? That sort of deal?

Yes. Also, I think your carb is not a 200, don't think that's a holley #, when you figure that out go to the link below and click the right link for your carb and you will find setup info.

http://www.carburetor-parts.com/Technical-Links_ep_649.html

here is a picture of the tag on my carb. I tried looking this up and that's how I saw it was a holley. can you give me more info based on this? Thanks a bunch for all the help, man. (hopefully the picture posting worked...)

If you look at my first picture above, the DOP is hidden behind the throttle lever. My part number is DOPF-9510-F.  The 9510 number is just a Ford designation for "carburetor." So, mine is a DOPF-F. Yours is a DOPF-F or DOPF-E, both of which translate to the Holley 1940.

I had the same issue on my 67 with a 240. The throttle return spring was weak. I replaced it with a new one and fixed the issue. You can try pushing back on the throttle lever while it is running. If the idle returns to normal then that is your issue.