the pocket guide to rochester four-barrel carburetors 1952

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The Pocket Guide

to

Rochester four-barrel

Carburetors

1952 - 1987

by

Gary Dickinson

CARBS Front Matter 2/7/11, 1:51 PM1

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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.


the pocket guide to rochester four-barrel carburetors 1952

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