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CRG Research Report

First Generation Camaro Water Pumps

© 2015, Camaro Research Group

Primary Author -
Reviewed by the CRG
Last Edit: 01-Jan-2015
Previous Edits:
Original Release: 01-Jan-2015
  1. Introduction
  2. Casting Numbers
  3. L6 Water Pumps
  4. Small Block Water Pumps
  5. Big Block Water Pumps
  6. Aftermarket Water Pumps
 

Introduction

Five different water pump types and eight different casting numbers were used on first generation Camaros. The differences are mainly in regards to engine type (L6, SBC, BBC) and pump type (short or long). The 1967 and 1968 V8 engines used the short water pump design and the bolt circle diameter to mount the fan on the water pump is 1.75 inches. The change to the long water pump design in 1969 on V8 engines was part of the V8 engine layout standardization. The fan mount bolt circle diameter was also changed to 2.30 inches in 1969.

There are easily recognizable visual differences of the short and long pumps. The distance between the pump back cover and the block mounting surface on a short pump is approximately 1 inch. When installed on an engine, it would be difficult to get your hand between the pump body and the engine block. This is not the case with a long water pump, since the distance between the pump back cover and the block mounting surface is approximately 1.5 inches.

Diagrams of the L6 and V8 waterpumps.
Water Pump Diagrams

 

Comparison of short and long water pump distances from block mounting location to the pulley mounting surface. The image is generic and the measurements are approximate. See text for exact dimensions.
Water Pump Comparison

 

Summary of Water Pump Casting Numbers

Water pumps with eight different casting numbers were used on first generation Camaros.
Each engine assembly plant cast their own water pumps. Some pumps that were cast at Tonawanda have a T on the casting.

Camaro Water Pump Usage
Year Engine(s) Type Chevrolet P/N  Casting Number Hub Height
1967 230, 250 L6 3876168 3788476 3 7/8"
1968 230, 250 L6 3929219 3788476 3 7/8"
1969 230, 250 L6 3947042 3788476 3 7/8"
1967-68 302 SBC short 3937936 3859326 5 11/16"
1967-68 327, 350 SBC short 3890017 3782608 5 9/16"
1969 302,307,327,350 SBC long 3957932 3953692 & 3927170  6 15/16"
1967 396 BBC short 3876173 3856284 5 3/4"
1968 396 BBC short 3927564 3856284 5 3/4"
1969 396, 427 BBC long 3953620 3931065 & 3969811  7 9/32"

 

L6 Water Pumps

The 230 and 250 cubic inch six cylinder engines from 1967 to 1969 Camaros used the same water pump casting, 3888476, for all three years. In 69, the hub changed to the larger fan mount bolt circle diameter.

Typical water pump used on 230 and 250 cubic inch engines.
L6 Water Pump
Casting date J 19 6 (October 19, 1966).
J 19 6 casting date
 

Small Block Water Pumps

1967-68

Short style small block water pumps were used for engines in Camaros in 1967 and 1968. The distance from the engine block to the pulley mounting surface on the hub (hub height) is 5 9/16 inches for the 327 and 350 cubic inch V8 engines and these engines used casting number 3782608. The Tonawanda 608 pump has two reinforcing ribs on the driver's side front; the Flint 608 pump didn't have the ribs.

SBC short water pump casting number 3782608. Casting date H 4 5 (August 2, 1965).
608 Water Pump
Back side (engine side) of a 3782608 SBC short water pump.
3782608 Water Pump back

The 302 cubic inch Z28 engines in 1967 and 1968 used casting number 3859326. The 326 pump has an inlet on the top of the pump for a "bypass" connection from the front of the aluminum intake manifold. The hub height on this pump is 5 11/16 inches. This hub height difference is presumably due to the wider harmonic balancer used on these engines.

The 326 pump was also on the high horsepower versions of the 327 engine (L79, L76, L84) with aluminum intake manifolds. These pumps were only cast at Flint, since it was the only plant that assembled Special High Performance (SHP) engines.
The correct tapped hole size in the top of the 326 water pump for SHP applications is 1/2 inch. Trucks also used this pump, but with a 3/4 inch bypass hole.

This SBC short water pump was used on 1967 and 1968 Z28 engines, casting number 3859326.
Short Water Pump Z28
Hub height of an aftermarket Stahl aluminum water pump for 1967 and 1968 302 engines.
67-69 hub height

1969

Long style small block water pumps were used in 1969 on the 302, 307, 327, and 350 engines. The hub height is 6 15/16 inches. Two casting numbers were used, 3953692 and 3927170. It appears that the 692 pump was produced at Flint and the 170 pump was produced at Tonawanda.

3953692 SBC long water pump.
SBC Long Water Pump
Angled view of 3953692 water pump.
SBC Long Water Pump
Back side (engine side) of a SBC long water pump.
3856284 Back

 

Big Block Water Pumps

1967-68

Short style big block water pumps were used on the 396 engines in 1967 and 1968. The hub height is 5 3/4 inches. The same casting number was used for both years, 3856284.

3856284 BBC short water pump.
3856284 Water Pump
Angled view of 3856284 water pump.
3856284 Back
Back side (engine side) of a BBC short water pump.
3856284 Back

1969

Long style big block water pumps were used in 1969 on the 396 and 427 engines. The hub height is 7 9/32 inches. Two different casting numbers were used, 3931065 and 3969811. ZL1 engines used the same cast iron water pumps as other big blocks, but the pump was painted black for use on the ZL1.

Casting 3931065 used for BBC long water pumps. It is dated I 10 8 (September 10, 1968). Note the T for Tonawanda at the end of the casting number.
3931065 Water Pump
Back side (engine side) of a 3931065 BBC long water pump.
3931065T Water Pump

 

Aftermarket Pumps

Several companies produce or have produced aftermarket water pumps. These are available in both aluminum and cast iron. These will not have a GM casting number on them in most cases, but may include the company name cast into the pump. Below are three aftermarket water pumps.

Aftermarket aluminum short water pump for 1967 and 1968 Z28 302 engines.
Aftermarket Stahl 67-68 302 water pump
Aftermarket aluminum big block Chevy short water pump.
Aftermarket Aluminum BBC short water pump
Aftermarket cast iron BBC short water pump with MADE IN USA casting.
BBC Short Water Pump USA

Acknowledgements

The author would like to sincerely thank the other members of CRG for their assistance with this report and use of their photos.

You can help serve to improve any future revisions of this report. We would appreciate notes of verified differences or other things that you feel are pertinent on this subject. Digital photos are greatly appreciated as well, since they serve to expand our knowledge of what is and is not correct for these cars.

 



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