Need carb help > Holley 4bbl

The secondaries on this carb only open about 1/8" while using the throttle linkage. I think i've found the problem, there is a set screw that activates the secondaries that HAS GOT to be out of whack. Anybody know how to reset it to where it needs to be?

This picture is at WOT

 

That carb has vacumm secondaries and they get pulled open when you vacumm reaches a certain point. There is a set screw in the c=base of the carb inder that gasket as I recall your secondaries should just be cracked enougn for you to see light through them. There is a number but I learned to do it by eye so I can tell you what feeler gauge to use.

 

Take that screw that's in the secondary throttle shaft plate out, and toss it.

Read up on "vacuum secondary" carburetors. Once you understand how it's supposed to work, you'll see why it's not supposed to be there, and why the secondary side is not supposed to open at all when you open move the throttle.

 

Hillbilly,
Someone has tried to do mechanical seondaries on a vacuum secondary carb. The screw in the linkage is NOT suppose to be there. The large "can" on the other side of the carb controls the secondary operation. There are 3 screws and one clip that hold the can in place. Take it off the carb. Watch out for the steel check ball. Look at the flange that was pressed against the body and you will see a vacuum port (between two screw holes) depress the rod into the housing and THEN hold your finger over the hole, release the rod and it should stay in place. If it comes out and or you hear a slight hiss, the diaphram is leaking or torn and will have to be replaced. look on the front of the air horn to find the Holley part number (i.e; 1850-2) to get a kit. A regular repair kit usually do not come with the secondary diaphram, check the kit in the store to make sure.

 

Well that explains alot. The screw didnt look like it belonged there anyways. I wonder what would posess someone to put that there in the first place? Perhaps that secondary diaphram went bad and rather than fixing it they put in the screw? I'll take a look see.

Thanks

 

Also, what is the plunger in this picture? At the moment it does absolutly nothing, nor does it even tough the linkage.

high idle?

 

That's a dashpot. It lets the carb ease back to an idle, as opposed to having the throttle plates slam shut quickly.

 

It used to be a common "trick" to done by guys who don't understand carbs, to make them think they were going faster. They'd feel the carb "kick in" when the secondaries opened too soon...although they didn't realize that what they felt was a lean bog....