73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: dopeeye on March 01, 2015, 09:31:08 pm
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I am trying to adjust the choke on a a 1975 Quadrajet M4MC. The truck stalls until its warm, have to feather it to just keep it alive. I was able to adjust the choke to where I think it was supposed to be but this was sheer luck. does any one have a manual on that choke adjustment ?
I have a single dashpot on the choke, see pictures.
I am close to just throwing in the towel and buying an aftermarket unit because i am trying to make this my daily driver. Any strong opinions ?
Thanks
Pete
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Adjust the choke stat (the black part) with the engine cold.It should close the choke plate with some spring tension on it.The screw on the choke opener is where you adjust how much it opens when started.There is a spec for it,but I've found on higher mileage trucks it sometimes doesn't work.Iadjust them according to the engines need
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Don't forget there is also the Fast Idle adjustment screw which can need tweaking as well.
Personally after the fiasco crap with my electric choke I'm almost tempted to go with a manual choke.
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what type of air filter do you have?
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Stock with a new element
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heat riser pipe in place and operational?
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Also read this:
http://www.chevelles.com/techref/Adjusting_Automatic_Chokes.htm
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heat riser pipe in place and operational?
Yessir
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read up here (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Service/ST_330_75_1975_Chevrolet_Light_Truck_Service_Overhaul_Supplement.pdf#page=237) it should be about the carb on your truck
ALSO (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Service/ST_330_75_1975_Chevrolet_Light_Truck_Service_Overhaul_Supplement.pdf#page=62)
a. Check carburetor for incorrect a n d /o r misadjusted
idle speed, float level, leaking needle and seat, air
valve, sticking choke or enrichment system and
secondary vacuum break operation. Adjust, repair
or replace as necessary.
b. Inspect carburetor fuel filter for presence of water
and/or impurities. Correct as necessary.
c. Check H.E.I. system as outlined in Section 6Y of
this manual.
d. Check, inspect and regap spark plugs. Replace as
necessary.
e. Check distributor spark advance mechanism for
proper operation. Repair or replace as necessary.
Inspect exhaust system for restrictions. Correct as
necessary.
f. Check carburetor mounting gasket for air leaks.
Repair as necessary.
g. Check and adjust valve lash.
h. Check for burned, warped or sticking valves. Repair
or replace as necessary.
i. Check engine for low compression. Repair as
necessary.
j. Check engine operating temperature. Correct as
necessary.
k. Check for loose, corroded or leaking wiring
connections (bulk-head connectors etc.) Repair as
necessary.
l. Check operation of exhaust gas recirculation
system. Repair or replace as necessary.
m. Check fuel system for leaks and/or obstructions.
Repair as necessary.
n. Check for vacuum leaks. Correct as necessary.
o. Check operation of EFE valve as outlined in
Section 6T of this manual. Repair or replace as
necessary
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Also read this:
http://www.chevelles.com/techref/Adjusting_Automatic_Chokes.htm
Wow great write up thanks for the link