Automotive Carburetion Made Easy
UM-900 (1952)
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IMPORTANCE OF ADJUSTMENTS
Continued
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The secondary
clearance adjustment on GM 4-Jet models prevents the secondary
throttle valves from opening until the choke valve is wide open. If
improperly adjusted, it may result in flat acceleration during warm-up
or a bind in the action of the secondary throttle valves. IT MUST BE
CORRECT.
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ON THE
ENGINE
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SLOW IDLE—The slow
idle setting is an important factor in smooth idling and stall-ing
after engine warm-up. It should be ad-justed carefully according to
factory specifi-cations with the use of a tachometer and vacuum gauge.
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FAST IDLE-The
final fast idle adjust-ment should always be made on the engine with
the use of a tachometer. Adjust accord-ing to factory specifications.
If improperly adjusted, it may result in hard starting when cold,
stalling or loading up.
THROTTLE RETURN
CHECK- Some Rochester carburetor models require a Throttle Return
Check assembly to facili-tate slow throttle closure to prevent
stalling on engines equipped with automatic trans-missions. If
stalling is experienced, check this adjustment. It must be made after
the slow idle setting is determined. Use two wrenches when adjusting
to prevent distor-tion of diaphragm.
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AUTOMATIC CHOKE
STOVE-Roch-ester Automatic choke carburetors for Chev-rolet
application require the use of a choke stove assembly and heat pipe.
For proper choke operation, this stove must be prop-erly installed.
Install on forward side of exhaust manifold. Do not insulate steel
heat pipe. The recommended installation gives best results with
factory calibrated parts.
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13
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