| choke question [message #204169] |
Tue, 09 April 2013 16:11  |
chasingsummer
Messages: 434
Registered: May 2011
Location: asheboro, nc
Karma: 0
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Senior Member |
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I am trying to confirm my choke is working properly.
I see that vacuum piece in front of choke coil keeps rear barrells closed.
Since my vacuum source for this piece is on the front of my carb, once warmed up, how does it loose vacuum so that my rear barrells will open?
Thanks to all,
brian
brian
asheboro, nc
75 eleganza, 74 build
119k miles and counting,
DOG HOUSE
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| Re: choke question [message #204170 is a reply to message #204169] |
Tue, 09 April 2013 17:02  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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On most Qjets the vac pulloff is for the choke and as a control on secondary air valve. Cold engine press foot to floor sets choke and Hi idle. Choke closed. On starting and developing vac comes up and opens the choke a few degrees ( a critical setting) within a second or so. Then the choke opens slowly via the bimetalic as it warms and opperator kicks down idle as warming progresses. Once choke fully open the secondary lockout tab retracts. When throttle is opened into part or all of the secondaries, the air flow, spring tension and vac pot balance how much the air valve opens and lifts rods. There is an orfice in the pot to control speed of opening upon vac drop. Vac is common to all four barrels to answer that part of question.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] choke question [message #204171 is a reply to message #204169] |
Tue, 09 April 2013 17:06 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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It does not lose vacuum. It aids in early choke pull off. If your choke
butterfly is not FULLY OPEN the blocking pawl for the secondaries will
prevent the upper butterfly from opening. The actual secondaries in the
throttle body are only mechanical. They open progressively with the
primaries, and should reach wide open throttle at the same time as the
primaries do. There is an additional weighted linkage on the passenger side
of the carb forward of and under the choke housing. It sticks. It will
prevent pawl retraction if stuck. Spray it with carb cleaner and follow
with compressed air.
Jim Hupy
Salem, Or
78 Gmc Royale 403
On Apr 9, 2013 2:12 PM, "brian" <chasingsummer@triad.rr.com> wrote:
>
>
> I am trying to confirm my choke is working properly.
> I see that vacuum piece in front of choke coil keeps rear barrells closed.
> Since my vacuum source for this piece is on the front of my carb, once
> warmed up, how does it loose vacuum so that my rear barrells will open?
> Thanks to all,
> brian
> --
> brian
> asheboro, nc
> 75 eleganza 2 74 build
> 118k miles and counting,
> DOG HOUSE
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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