Before I start trying random things I thought I would ask for some suggestions on how to get my engine to idle below 1800 RPM

I backed the idle screws all the way back and it will stall: no idle at all.  just maybe a 1/4 -1/2 turn and it idles at 1800.  I am wondering if it might have something to do with the bowl settings.  When I 1st installed the carbs they shot fuel out of the overflow tubes.  I tightened the large screws on top and got it to stop but I was left with this high idle speed.  Any thoughts or suggestion on what I could try?

Thanks

Holley 600's

I thought this might be the problem...

Chaz,  Were did those carbs come from (were they shipped UPS?)? 

The fuel overflowing is a sign that the float level is way off.

I've said this on several other threads, but I would start by removing all four float bowls and checking the float level.

Removed and inspect the needle and seat assemblies for debris.

Set your mixture screws at 1 1/2 turns out on both sides (run all the way in lightly then turn out 1 1/2 turns).

Set initial timing to about 16BTDC and 36 degrees at 3000rpm, then adjust idle speed setting.

*** make sure you have all the vacuum ports plugged off before trying to tune 

OK let's ask some things here.

Vaccum leak - did you spray carb spray around EVERYTHING to see if it affected it?
Did you check or temp plug the PCV?

What size cam, IE duration @ .050 do you have?

Did you set the timing? Did you try it with the vac advance unplugged? Did you verify the vac advance is plugged into the port above the idle screws?

Have you verified the secondaries are fully shutting?

Have you attempted to verify that both of the primary throttle blades are open approximately the same(or use a uni sync to adjust - that is what I do to mke sure the flows are the same)

There are other things it could be too - but check these first.

Vaccum leak - did you spray carb spray around EVERYTHING to see if it affected it? Carb Spray?  So No, but I did attach a vaccum gauge and it read very close to OK (approx 23) at the high RPM idle.  I also double checked every bolt for torque.


I'm surprised you are pulling that high, but OK.


Did you check or temp plug the PCV? Doesnt have one

What size cam, IE duration @ .050 do you have? 218* for now

OK, that rules out a few things.


Did you set the timing? Messed with it a bit, will try with the timing light tomorrow in the water.

You can seriously mess with the idle if you have the advance set wrong. If you get on it while it is really advanced, you will have major pinging too...



Did you try it with the vac advance unplugged? Yes, It is always disconnected and unplugged

Did you verify the vac advance is plugged into the port above the idle screws? See above

OK

Have you verified the secondaries are fully shutting? No, cant see top of carbs with scoop bolted on.  I will remove it tomorrow at the lake. 

You can do that from the side of the carbs - hit the secondary linkage and see if it closes.


Have you attempted to verify that both of the primary throttle blades are open approximately the same(or use a uni sync to adjust - that is what I do to mke sure the flows are the same).  Again I will eyeball them tomorrow, but I did check idle adjust screw and turn them both as close as possible to the same amount out that it will still idle.

What should I look for/ set at for the float levels after I take the bowls off?  I have never seen the inside of a holley carb...

Your float levels should be set so when the big screw on the side of the bowl is removed, gas is just below or trickling out. You don't need to remove the float bowls to adjust.


Is it idling that high because you set it (it wouldn't run below a certain RPM), or because you started it and it was that way?

Basically that is the way it idles.  It will not stay running if I try and lower it with the screw.  It is, however, maybe 1/8- 1/4 turn past just touching to keep it running at 1800 RPM's