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ROCHESTER CARBURETORS Bulletin 9D-31 3-10-55 |
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United Motors Service
DIVISION OF GENERAL MOTORS
CORPORATION |
Bulletin 9 D-31 |
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Date:
3-10-55
Page
1
Supersedes 9 D-31 Dated 11-1-49 |
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GENERAL
OFFICES—DETROIT
ROCHESTER
PRODUCTS |
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CARBURETOR BULLETIN
SUBJECT--CADILLAC
Reported Service Complaints on 1955 Model
Carburetor.
1. Border line lean condition at speeds of
20-40 miles per hour. Consistent operational hesitancy of the engine takes
place in this instance throughout the above speed ranges. Engine lacks
solid feel.
2. Stumble on light acceleration. This
condition can be corrected by replacing with the new type No. 7000208 Pump Plunger
Assembly and the No. 7000204 Power Piston Assembly.
Note: The No. 7000208 Pump
Plunger and No. 7000204 Power Piston are now in production.
3. Stumble and shudder upon light acceleration.
It was found that improper adjustment of idle - i.e, air adjustment screw turned out as far as 9
turns. Idle adjustment screw
turned out excessively to balance large volume of air. This brought about
an excessively rich idle mixture which created so heavy a draft on the
fuel in the carburetor inner well that on light acceleration the
distance of fuel left in the
main well tubes was increased to a point sufficient to cause light part throttle
leanness.
This situation brought about Item
3 above - stumble and shudder. Correct adjustment of the Idle Mixture
eliminates the stumble and shudder characteristics,
The lean condition between 20 and
40 miles per hour can be corrected by installing No. 7008768 Primary
Cluster in the No. 7007970 and No. 7007971. Production carburetors
equipped with this new cluster will carry XB tags, February 1955. Latest
specifications Idle Tube . 031, Idle Restriction .057. Venturi Cluster No. 7008770
for carburetor No. 7007240 Standard Front Eldorado and No. 7007942
Standard Rear Eldorado, also No. 7007241 Rear Air Conditioned
Eldorado.
The above corrections need be
made only when customer complaints indicate poor performance in the above
mentioned instances. It is suggested that thorough inspection of the
engine, ignition system, ignition timing and possible accessory manifold
air leaks be carefully checked before any attempt is made to make changes
in present carburetors.
Policy: This modification is to be handled on a maintenance
basis.
(0466 PD 3-55)
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(Printed in U.S.A.)
AA.GO:9, WD, 131, 132:9-13 |
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