Holley 350 2 barrel Help

[Marine05]

Just got my Holley 350 2 barrel set up on my 81 mustang 200. When I go to fire up the motor, it just runs away on me. It seems to run strong but the the rpms just race off so i have to shut it down quickly. I played with the idle adjustment and mixture screws but to no avail could i get it to come down. I am out of things to look for. No vaccuum leaks, everything is vacd off the heater tree with straight manifold vac. Float height is good but cant get the rpms under control. Its a used carb but its in perfect working order, so i thought.

If anybody can tell me anything or help me out, it would be greatly appreciated. Thnx.

 

[Bort62]

If your throttle is not stuck open and you are having the problem you describe, you have a vacuum leak by definition, and it sounds like a fairly major one.

 

[Marine05]

the only vac line i aint got hooked up is the one for the temp sensor that goes to the air horn. But thats it. I am stumped.

 

[Bort62]

Well, the air is getting in there somehow...

 

[Anlushac11]

time for the spray bottle of non detergent windshield wiper solvent.

Or I guess you could use a spray can of carb cleaner. Spray around one area of the carb and carb base at a time and see if the idle smoothes out. If its running away you may need someone in car to shut it off while your under the hood.

I have seen used carbs with worn out plastic bushing in the body that let air in around the shafts.

 

[wsa111]

Is the fast idle screw turned in too far & you cannot adjust the curb idle properly.
Otherwise Ian said you may be chasing a major vacuum leak.
I have never had a problem adjusting the idle on the 7448-350 carb.
As far as main jets go if its a n/a engine go with 59 main jets. Bill

 

[MustangSix]

Open these instructions. http://www.holley.com/data/Products/Tec ... 7950-7.pdf

Look at Figure 6 on page six. You'll see a large vacuum port on the back of the carb. If that is open, the engine will run away as you describe.

 

[BUZZ]

Your choke linkage may be bent or stuck. I see from another post that you used the Summit adaptor. Which carb gasket are you using I didn't have a problem with the thick one but when I used the thin one the throttle linkage on the choke side would bind up on the adaptor, I had to cut a small slot in mine to make it clear.

 

[Marine05]

I dont have any binding, everything clears with no problem. Ill get a pick of everything and post it all to see if anybody can see anything. I have no idea what is going on. Short of cranking all the mixture screws out and starting from scratch, no idea where to begin.

 

[gtm1086]

It is very easy for the throttle plates to be hanging open on the adapter and or gasket. You might want to double check

 

[Marine05]

Checked the throttle plates on the carb yesterday. Not hanging up, linkage is not binding or dragging, pumps fuel as soon as the linkage is moved. Backed the curb idle out till it barely touched the linkage with no change. Tried to lean the mixture out but its still running away. Checked and rechecked all the vaccuum lines. Still stumped.