| Curious choke discovery [message #243183] |
Wed, 12 March 2014 14:02  |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
Karma: 0
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The choke on the Twinkie II never worked correctly. It took too long to come off and it had to be adjusted way past the maximum lean mark to work at all.
A friend gave me a GMC Motorhome Q-Jet, same number as the one I already had, that I was going to rebuild. When I removed the choke I noticed there was a tiny plastic tube between the choke housing and the carb body, maybe an eighth of and inch in diameter and half an inch long. I had previously removed the choke from the Twinkie II and this part was not there. It was also not on a 403 carb I had looked at.
I installed this little tube on the Twinkie II choke and it now works perfectly. So here's my question.
It seems odd that the tube would be missing from both carbs that I had, both of which came from running engines. Has anyone else run across this? Does the plastic rot and they fall apart? Do people rebuild the carb and leave them out? Just bad luck?
What I am referring to would be where part #57 would go in this image, although here it is shown a just a washer.
http://www.carburetorfactory.com/images/expvw27.jpg
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Curious choke discovery [message #243187 is a reply to message #243183] |
Wed, 12 March 2014 14:24  |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
Karma: 3
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That is a seal for a vacuum port which pulls the hot air through the choke thermostat. Older carbs used a cork washer-like seal and newer ones used the small white plastic tube thing.
Without some kind of seal the vacuum from the port on the side of the carb leaks and no (or very little) hot air is pulled into the choke thermostat and the choke never gets hot enough to open fully.
When converting to an electric choke that vacuum port can be plugged off so there would be no cold air to cool the electrically heated element, this makes for a very quick-opening choke. On my GMC from fully cold to fully wide open and fast idle completely off is about 3 minutes on a 60 degree day.
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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| Re: Curious choke discovery [message #243189 is a reply to message #243187] |
Wed, 12 March 2014 14:28 |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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Thanks Bob, that's about how long mine takes now. I'm just wondering why the tube would be missing on two carbs. That seems odd.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Curious choke discovery [message #243214 is a reply to message #243189] |
Wed, 12 March 2014 18:43 |
mrgmc3
Messages: 210
Registered: September 2013
Location: W Washington
Karma: 2
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| Otterwan wrote on Wed, 12 March 2014 14:28 |
Thanks Bob, that's about how long mine takes now. I'm just wondering why the tube would be missing on two carbs. That seems odd.
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Cork that rotted and was ingested by the vacuum port....or someone rebuilt it and did not realize the need to seal this joint
Chris Geils - Twin Cities / W Wa
1978 26' Kingsley w/ very few mods; PD9040, aux trans cooler, one repaint in stock colors, R134a, Al rad, Alcoas, 54k mi
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