Another Question About Chokes/Carb

[snarlingmastiff]

I have a '72 F100 with FE390. The guy I bought it from chuckled as he told me it hates to start cold. Well turns out the choke tube (hot air tube) is completely missing (no wonder you can't start it in the winter time in Nevada). I have found some great information here on how to fix that. However, I realized that there is another part missing and I'm actually not sure what it is.

In the attached image, the front (and new looking) tube is the hot air into the bi-metallic spring. What is the tube behind it? I have neither in my engine bay.(http://www.fordification.com/forum/down ... w&id=34996)

A big thank you to "patrickdotryan" for the choke tube replacement how-to and for the wonderful picture.

[idaho_cowboy]

Isn't that just providing warm air to your air cleaner assembly?

- Joseph

[snarlingmastiff]

Thanks for responding Joseph. If that is the case, my follow up questions are: What ports/parts does it connect and do I need it? I am finding very little information on what tubes/hoses should go back there and where they connect to.

Cheers

** EDIT/UPDATE
In trying to replace my choke tube, I have found that someone tried to drill out the port at one point and it is now 1/4" instead of 3/16" and I have to find another fitting. Any suggestions?

[Mach428]

The metal line with the rubber tube connects to the air horn of the carburetor at one end and the exhaust manifold at the other end. If your carb has a port at the top with a metal pipe, then can use this setup. If not, the one connecting the exhaust manifold to the choke spring will work fine.

I have three Fords, one with one without the secondary line and they both work fine

[snarlingmastiff]

Thanks Mach428. After seeing some other posts I came to the same conclusion and have been running it this way. It seems to work, the tube gets hot. the thermostat warms up. Now I am just struggling with the settings. It tends to get stuck with the choke on (fast idle screw is finicky). I only got the fast idle to work once. I think part of the issue is it's not quite cold enough where I live at the moment to really need the choke. As is, the engine starts fine if I just baby it a little for the first 30 seconds or so. I would simply like to not have to do that. My goal is to neutral, gas, start, warmup. Nothing else should be needed.

I am currently waiting for a new thermostat spring, since my current one is an original and rusted. I am also starting to think the whole carburetor probably needs a rebuild. Maybe that will be my project this winter when I get a free weekend.

[1972hiboy]

one tube is for hot air to bi-metal spring and into carb vac port. and one tube for filtered air to exhaust manifold.