Electric choke question

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Craig Contact options for registered users 's Avatar posted on
April 5, 2007, 4:15 am
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I have an 81 chevy 4x2, with a quadrajet carb, wiht an electric choke.  I
understand that there is a bi-metalic spring which heats up and opens the
choke slowly as the engine warms.  I also understand that if the spring is
tighter, than the choke will open slower.

With an electric choke, it gets a steady 12V current.  How does that decide
when the engine is warm?  I've got the choke as tight as it will go, all the
way back, but it still opens long before the engine is warm.  Does the
current to the choke change in any way, because if it doesn't, how would a
steady current know when the engine is warm?

I live in Canada, eh, and when it gets cold, I need the choke to stay shut
longer.  Right now, it opens with 5 minutes, and the engine has barely
started to warm up.

TIA.


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aarcuda69062 Contact options for registered users 's Avatar posted on
April 5, 2007, 10:12 am
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Re: Electric choke question





I would suggest that you look for other problems.
Is the EFE (heat riser) valve working?
Is the exhaust passage in the intake manifold open (not plugged
with carbon?
Heated air intake in the air cleaner snorkel,  the flapper valve
shouldn't open until the air in the air cleaner reaches 110*F
Vacuum leaks?
Engine coolant thermostat?

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El Host Contact options for registered users 's Avatar posted on
April 5, 2007, 6:04 pm
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Re: Electric choke question





Easy enough, move to Houston Texas. That should fix it.
lol j/k.

I can tell you the current is probably not changing, you might not be
getting any voltage at all, check it with a voltmeter.
I believe there is an adjustment screw for fast idle. If it is not set right
the fast idle cam will not have anything much to hold it in place, making it
easy for the fast idle cam to fall back down which would open the choke up.
Either that or you may need to replace the electric choke.

This may help:
http://www.442.com/tech/rochester.html

You may give the fast idle screw a half turn clockwise.



 

Craig Contact options for registered users 's Avatar posted on
April 7, 2007, 4:51 am
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Re: Electric choke question



I['m having trouble understanding the fast idle cam.  As far as I know, it
works on vacuum supplied by the engine. As the engine warms, vacuum
builds(hence the need for fast idle, to build vacuum to bring in the mixture
of gasoline and air when the engine is cold, am I right?). So if the fast
idle cam is not adjusted right, then it might not hold the choke closed,
when there isn't enough vacuum built up in the engine?  And if so, is there
an adjustment for the fast idle cam?

As for the choke coil, the bi-metalic coil that heats from the current, I've
got it set all the way back towards the firewall, so that the spring is as
tight as it can go.

Thnx for explaining to this Newby!


 

Big Al Contact options for registered users 's Avatar posted on
April 7, 2007, 1:00 pm
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Re: Electric choke question





The fast idle cam is hooked to the choke. There is a vacuum "pull off" that
opens the choke a bit when the engine starts. The choke heater, the round
plastic thing with three screws holding it, has marks to align it. It should
not be as tight as you can go.

Al



 

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