Vac Choke Pull-off Question

[scorp1us]

I was able to to the Tim Test. It started and ran beautifully with the vacuum directly on the 2ndary choke pull off. I took the vac hose to the solenoid and put it right on the diaphragm nipple.

Which raises two questions: which is the failed component needing replacement (and how to find it) or can I just run the engine like that?

[Tim Potter]

I was actually wrong about the function of the TVS with your vacuum pull off. It does nothing for the pull off, it only controls whether you get ported or manifold vacuum to the vacuum advance can. It determines which vacuum to supply based on engine temp. It is the hi temp switch, it opens at about 110* of water temperature.

the only components that effects the vacuum signal to the pull off is the vacuum valve solenoid. You could test it if you so desire. There is a switch on your tranny that sends an electrical signal to open the solenoid allowing the vacuum, supplied by the port on the back left of the carb, to be applied to the pull off.

so really there are two things. the pressure switch (might be tranny temp sender, I'm not exactly sure but, temp makes more sense) and the vacuum valve solenoid.

Here's what I'd do if I wanted to test it. Bypass it. And "T" into the "in" port, attach a vacuum guage to the "out" port. Put the guage on the windshield with the hose under the wiper or run the hose into the cab. Test drive and see if there is vacuum being applied to the guage and note the circumstances. If no vacuum occurs then one of three things is true. The solenoid is at fault,the sender is at fault or the wiring is at fault. The wiring can be traced to the source which may give some indication of how the thing is supposed to work.

I don't know enough about the tranny sender/switch to tell you what readings you should get or within what range with a multi meter. It has been discussed here before a few times:
Here's a start:http://www.binderplanet.com/forums/s...ad.php?t=91949

Pay particular attention to post # 13 in this thread: http://www.binderplanet.com/forums/s...+sensor&page=2

Bypass sounds pretty good to me.

All I can tell you is that mine stopped working in or before 1990. The damn choke gave me fits for a long time. It's been bypassed ever since and my engine runs great. I ran it like that with a TQ installed for several years. Then I decided that a Carter AFB would be better than another TQ rebuild, and it has an electric choke instead. Never looked back.....maybe a little sideways once in a while........

[scorp1us]

Thanks Tim, Scott.

I have an update and it is a revelation. While I've been focusing on the choke pull-off, its been the wrong one. Today I started it and it had issue running, even with the 2ndary choke on a vacuum line. It was a challenge to get it running, but I eventually did. I went to the other side of the engine and fooled around there. That's when I realized I have _no_ vacuum at the primary choke port!! So I disconnected the hose that goes to the air horn and plugged it into that T. And it ran fine. I don't know why it ran fine yesterday....

So now I have to figure out why that port is plugged and some way to unplug it. In the mean time, can I run it in the current setup, or should I add a T and plug the air cleaner hose back on. I don't really know what those two lines on the air cleaner do...?

Edit: come to think of it, I think it was plugged on the old carb too... I'll have a look-see after work...