Vintage Mustang Forums banner

Engine Question

808 Views 2 Replies 2 Participants Last post by  Guest

A while back I posted on breaking a small tube that comes from the bottom of the exhaust manifold and attaches via a rubber hose to the inlet on the air horn of my 2100 carb.

Prior to it breaking I had made a discovery that has me wondering about it's significance.

I discovered that my car had trouble idling nicely with the hose properly connected. When I took it of the air horn, the car immediately idled great, only at pretty high RPM's.

So, now I'm wondering. Is this normal, or is the thing not working properly due to a clog of some kind in the lower exhaust manifold?

Anyone care to explain and get promoted to a higher status along the way?


First time '66 Mustang rolling restoration, nearing completion.
1 - 3 of 3 Posts

· Registered
4,046 Posts
Over time it might have clogged up. Making the need to idle it up over time also. Then when you removed (broke) it, it freed up & idled high. Sounds good to me :)

66 Coupe, 302, Auto, 3.25 gears. Candyapple Red with White Pearl Stripes. Cragars.

I'm sure when you posted the last time somebody told you that you broke the cool air side of the choke stove. All the rubber tube does is ensure that the air being drawn into the choke mechanism is pulled through your air cleaner and not from inside the engine bay. If you leave it off for an extended period of time the choke housing will get gummed up from dirty air being pulled in.

Removing the hose from the air horn would be the equivilant of breaking the connector at the bottom. The choke is no longer drawing air through the air filter.

Is your air filter clean? If it's not it could be preventing the proper amount of air from being pulled into the choke.

By pulling air from the engine bay the choke doesn't have to compete with the venturis for the filtered air and it will alter the carb vacuum dynamics a bit. I can see here the engine would idle higher and smoother by taking it off. Turning the idle speed up with the screw would have the same effect though I suspect.

The car wasn't designed to be run with it off. Mine broke off too and the PO just removed the hose and left it off. The choke eventually froze and I had to take it apart and lube it up. I currently have the exhaust manifold in my girlfriend's basement. I'm going to drill out the bottom of the choke stove, JB weld a piece of tubing in there and run a new rubber tube to the carb. Hopefully I won't have to mess with the choke for a long time after that
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.