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The Pocket Guide
to
Rochester four-barrel
Carburetors
1952 - 1987
by
Gary Dickinson
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Copyright 2011, Gary Dickinson
All rights reserved by the author. No part of this publicationmay be reproduced, stored in a retrieval system, or transmittedin any form or by any means - electronic, mechanical,photocopy, recording or any other - except brief quotations inprinted review, without the prior permission of the author.
Cover design by Gary Dickinson
Printed in the USA
ISBN: 978-0-9826118-5-2
EVEREADY PRESS
1817 Broadway . Nashville, Tennessee 37203
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This book has been “in process” since 2005. The
concept started as I stared at two piles of carburetors
and had no idea what 99% of them were. They all had numbers; but it was like reading a foreign language.
When I asked friends who are GM-retired and Rochester-retired Mechanical Engineers about
carburetor information, they convinced me there was
no single source for identifying Rochester carburetors. There is information on the Internet; but much of it is
contradictory and little, if any, is documented.
So with guidance from these retirees and fellow club members, my journey began. The more I looked, the
more I realized how much of the information posted on
the Internet was “speculative”. As my research continued, I began to understand that without reliable
sources, much of the “incorrect” speculation posted on
the Internet has become reality . . . a false reality!
Hopefully, this book will replace the speculation with
documented reality. All of the information is organized
in numerical part number order which allows for quick and easy identification of thousands of Original
Equipment and Service Replacement carburetors.
A Message from the Author
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Author’s Message continued This Pocket Guide contains over 2,200 four-barrel
carburetors; beginning with the 4G model in 1952,
continuing with the Quadrajet in 1965 and ending with
the last Quadrajet produced in 1987.
The size of this Guide was chosen to allow for the most
information to be placed in the smallest format possible, so it is not difficult to work with while walking
through a junk yard or swap meet. It’s great to use on
any of the on-line auctions too and once it is used to verify what a seller says, it will really open some eyes!
At some point, a decision had to be made about when
all of the known information had been found. I think that time has come. I hope you agree and find this
Pocket Guide useful.
Gary Dickinson
For additional informationgo to www.carb-book.com
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Service Publications: GM, Rochester, Delco & United Motors Service
Assembly Manuals: GM-Divisions
Sources & References
This is the only book listing thousands of Rochester
carburetors by year, make, model and application that
has been fully documented by multiple factory sources.
However, for protection of the data, the references are
not listed.
Original Equipment Manufacturers (OEM):
GM, Ford, Packard & Chrysler
Technical Service Bulletins (TSB’s):
GM, all GM-Divisions, Rochester & United Motors Service
GM Microfiche Records
Service Campaign Bulletins
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The Pocket Guide uses abbreviations of terms similar
to those used by GM, the GM Divisions, Rochester
Products and United Motors Service that are concise, easy to read and understand. Here is a brief
description:
AC = Air Conditioning
AT = Automatic transmission
C10, C20, C30, C50, C60 = Describes a two-wheel
drive GM truck. The “C” signifies two-wheel drive and
the numbers “10”, “20” & “30” denote the carrying
capability; 10 = 1/2 ton; 20 = 3/4 ton & 30 = 1 ton. C50
& C60 are 1 1/2 & 2 ton trucks. The numbers are
Chevrolet truck designations and the GMC equivalent
is 1500, 2500 & 3500; or 55, 65, etc for the large
trucks. This book uses these numbers as capacity
references, not specific to Chevrolet or GMC. If the
listing denotes Chev - GMC and the number “10” is
used, it means that the carburetor is designed for “half-
ton” capacity for both of the Divisions.
Glossary
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Glossary continued CALIF = Denotes carburetors designed for California
only emissions.
Early production = Indicates carb use during the early
part of a model year.
Federal = Vehicles with emissions for all states except
California; also termed as “49-state” carburetors.
G10, G20 & G30 = The “G” series trucks are GM’s
vans. The capacities “10”, “20” & “30” are the same as
C & K trucks.
High Altitude = Carburetor designed and tuned for
altitude
H.O. / High Output = A term used to denote high
performance
HT = Hydramatic transmission
K10, K20, K30 = Describes the drive system and
capacity of GM’s trucks. The “K” signifies four-wheel
drive while the numbers “10”, “20” & “30” denote the
carrying capability: 10 = 1/2 ton; 20 = 3/4 ton & 30 =
1 ton. These are designations used on Chevrolet
trucks and GMC’s equivalent is 1500, 2500 & 3500.
Only the 10/20/30 designation is used to save space.
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Glossary continued Late production = Indicates carburetor use during the
latter part of a model year production. The exact dates or
car numbers are rarely defined by GM or Rochester
records.
Marine = Denotes a carburetor manufactured for marine
use MH = Abbreviation used to denote Recreational
MT = Manual transmission
MT/AT = Manual or Automatic transmission uses
P30 = The “P” series GM trucks are “tilt-cab” units
frequently used as motor homes or commercial trucks.
The 30 = 1-ton.
Replacement = A term used by Rochester to denote a
late 1970’s and 1980’s Service Carburetors
SC = An abbreviation used to denote a Service
Carburetor; this includes Parts Department carburetors
w/ = Denotes an option or emissions (w/ AC; w/ A.I.R)
MH = Abbreviation used to denote RecreationalVehicle or Motor Home use
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Glossary continued w/o = Denotes vehicles without an option (w/o AC)
w/ or w/o AC = Used to denote vehicles “with or
without” factory air conditioning
1st type; 2nd type; 3rd type = These are terms used
by Rochester and are similar to the “early” or “late”
production terms used by GM. These terms denote a
modification or change (however minor) for which a
new carburetor number was assigned; therefore, the
“1st type” or “2nd type” etc.
4v = Denotes four venturi or four-barrel
49-state = Vehicles with emissions for all states except
California. This is also referred to as “Federal”
50-state = Vehicles with emissions for all states
including California
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Confusion & Speculation
For those who compare the information in this book
to Internet sites, much of the information will not be
the same; most Internet sites do not use factory
documentation. Comparing non-documented facts
with documented facts can cause some confusion.
Many of the Internet sites ask for information from readers or contributors: “Tell us about your carburetor
and what kind of car it was taken from”. Some rely on or use speculation, based on a few known facts. Those
few facts are generalized into facts that involve all Rochester carburetors. It simply is not so . . .
Speculation is difficult to identify, explain or refute. It
has become our “carburetor reality”. For example, several Internet sites list a 7027276 for a ’67 Firebird
400 Ram Air. However, GM, Pontiac and Rochester
do not list this number as ever produced. So how did
someone “find this number”?
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There may be an explanation . . .
It is an “accepted truth” posted on Internet sites that a
702xxxx is a carburetor without emissions and a 703xxxx
is one with emissions. The “2” or the “3” are the key,
according to the Internet sites. That is almost factual . . .
Since Pontiac used a 7037276 on a ’67 Firebird 400 with
Ram Air and A.I.R. emissions, someone must have
incorrectly concluded that the 7027276 must be for a ’67
Firebird 400 with Ram Air but without the A.I.R.
According to GM and Rochester, the 7037276 is for a
Firebird 400 Ram Air with or without A.I.R. There is
no carburetor built with a 7027276 designation!
Documentation is important, as evidenced by the Firebird
example. We can now conclusively say that speculation,
conjecture and faulty reasoning have been replaced by
factory documentation.
This Pocket Guide ends any need for future
speculation.
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