Carb Mystery!

144-250 cid Inline Six Performance
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Adams
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Joined: Mon Aug 03, 2015 1:01 am

Carb Mystery!

Post by Adams »

Ok, I just put a nice rebuilt Holley 1909 on my 144. It ran great, so I turned it off and then fashioned a hot air choke tube for it. After installing that, I turned the car back on, and for no apparent reason it started sucking vacuum through the auto choke housing! (Through the opening that the choke tube screws onto). What the heck is going on?? I didn't even think there was any kind of vacuum connection to the thermostatic spring area of the choke--

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poboyjo65
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Re: Carb Mystery!

Post by poboyjo65 »

I'm not sure on that carb but autolite 2100's & 4100's do that,& is normal.
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Johno

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Re: Carb Mystery!

Post by comethead »

Sucks air through there to heat up the choke element faster. So there's always a vacuum leak there.

Joe
1965 Caliente HT- 289/4 speed
1964 Falcon HT- track car- 302/4 speed
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Adams
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Re: Carb Mystery!

Post by Adams »

Ok, Thanks--I noticed by sucking on it that a passage goes down to the carb base. My next question...where the hole is in the top of the exhaust manifold--does it "dead end" or go all the way to the bottom? In other words, is air being sucked through constantly, or is it just a vacuum pulling on the dead end hole?

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poboyjo65
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Re: Carb Mystery!

Post by poboyjo65 »

again, I'm not familiar with a 6 cyl. but 289's have another tube on the choke stove that has a rubber hose that goes to the breather, so it is drawing in clean air, to be heated by the exh manifold, then to the choke. yours most likely has the other tube, may be broke off by now.
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Johno

Adams
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Re: Carb Mystery!

Post by Adams »

Thanks for the help--I just looked, and yes the hole goes through, just a simple setup with no filtered air. I'm guessing an idle adjustment on a manual choke would be much leaner than with an auto choke...

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