Index

• Radiator Usage
• Radiator Tags
• Radiator Applications
• Fan Shrouds
• Cooling Fans

Introduction

All first-generation Camaro radiators were manufactured by the Harrison Radiator Division of GM and were of the cross-flow design type (as opposed to earlier vertical flow designs). Hot coolant from the engine enters the upper left-hand side of the radiator and is cooled as it passes through the radiator core, exiting the lower right-hand side into the waterpump (RH and LH as observed from the driver's position).

The basic cooling system design is robust and with proper maintenance, will last for years. See JohnZ's Cooling Basics for practical information about the proper functions of the components and system.

Radiator Variables

Radiators for cars with automatic transmission included a transmission oil cooler in the passenger side end tank; manual transmission radiators did not have this provision. The fin spacing is also smaller for automatic radiators (smaller fin spacing increased the radiator's heat rejection capability) to compensate for the increased heat input from the automatic transmission. (Note that radiators sold for service use are often generic and include the transmission cooler provision even for manual transmission cars.)

A heavy-duty radiator was available by ordering either of two options. Regular Production Option (RPO) V01 was the heavy-duty radiator option and was available with all engines except the Z28 or big block engines. All vehicles optioned with air conditioning (RPO C60) also received a HD radiator.

Axle ratio did not affect the radiator usage with one (unverified) exception. In the April 1 1969 revision of the dealer ordering information, it states that Positraction Rear Axles: Ratios 3.73 or 4.10 without Special Performance Package (Z28) or 396 engine "also includes HD radiator" and the MSRP is $56.90. This means that a SS350 (or L65 or 307) with 3.73 or 4.10 gears would automatically get the V01 radiator. This would also apply to COPO 427 cars (and the higher price showed up on some later COPO window stickers), but they already received a 4 core radiator as part of the COPO package.

Radiator Usage

On all 1967-9 L6 cars, adding RPO V01 or AC resulted in use of a radiator that differed from the standard part only by the use of smaller fin spacing.

For 1967 and 1968 small blocks, adding V01 or AC increased the radiator from a 2-row core to a 3-row core (1.98-inches thick). The V01 or AC radiators for the 67-68 L30 and L48 engines also received a wider 23-inch wide 3-row core. But in late 68, the AC or V01 radiators for L30 and L48 engines changed to a 21-inch core instead of a 23-inch core. We don't know the reason for this application change, but it was consistent with the upcoming 69 usage.

For 1967 big block engines, AC was not a factor in radiator selection since the SS396 was not available with AC in 1967. For 1968 big blocks, AC was an available option for the L35 and L34 engines and increased the radiator from a 3 core to a 4 core (2.70 inches thick). Note that this was a straight neck radiator, unlike the 69 curved neck radiators that used the same broadcast code.

For 1969, all small block radiator cores were 21-inches wide and all big block cores were 23-inches wide. On 1969 small-block engines, adding V01 or AC increased the size of the radiator core from 2-rows to 3-rows. Addition of AC to 1969 big-block engines increased the number of radiator core rows from 3 to 4 and added a curved inlet neck in order clear the 1969 AC components. 1969 COPO 427's (see CRG COPO Research Report) also used this same curved-neck 396/AC 4-row core radiator - eliminating the need for the assembly plant to stock a straight-neck 4-row in 69.

If there was a production shortage (a relatively infrequent event), a larger capacity radiator would be substituted.

The top and bottom plates of the original radiator core for 2, 3, and 4 cored radiators have a unique hole pattern (the top and bottom plates are the same). Research at Harrison Radiator by Tom DeWitt has shown that the adjacent rectangular and square holes near the ends of the top and bottom plates were used by Harrison to hang the assembled radiators on their paint hooks. Most replacement cores do not have these holes. Below are two pictures of original radiator top plates showing the hole pattern.

1969 2-Row Core Top Plate		1968 3-Row Core Top Plate

Radiator Tag Decoding

1967 UA and UN Tags

1968 UC Tag

1969 ZH Tag

The 1967 tags just had the broadcast code and the part number on it.

The 1968-1969 version of the radiator tag was larger than the 1967 tag with added information. The 68-69 tags have codes for the radiator end tanks in a smaller font next to the broadcast code. Beneath the tank codes is a 1 or 2 digit number that identifies the radiator core assembly to be used in that radiator. To the right of the core assembly number is the letter O, R, S, or nothing. The meaning of this letter is unknown. The extra number stamped on the bottom edge after the part number appears to be the year of manufacture. (It's believed to be the calendar year, not the model year, but there is some conflicting data.)

The end tank codes were used by the radiator assembly plant to identify the different tank designs and use them in the correct radiator assembly. The month code (letters A through M format, excluding I) is stamped on the RH end tank between the letters of the tank code. The tank codes and applications are shown in the table below.

A 1969 small block automatic transmission radiator tag in the installed position on the radiator is shown below; the tag tells us that the ZA radiator should have IH and OF end tanks and a #32 core. To the left of the tag is the OF tank code and between the O and the F is the month code, a C (for March). To the right of the tag is the clip to hold the overflow hose from the radiator cap.

1969 ZA Tag

Radiator Applications

Table cells colored in blue denote verified data (via cars or broadcast sheets), while the data in uncolored cells come from GM documentation. Cells colored in yellow denote assumed data based on GM documentation that suggests the listed usage. We would appreciate help with increasing the number of table cells that are confirmed via data from original cars.

In several applications, radiator usage changed during the production year. Both radiator codes are noted in the table with a reference to early or late production.

Note: the late 68 L30/L48 V01/AC radiator is indicated in GM documentation to change from the 23" version to the 21" 3010178 (manual) and 3010179 (auto) radiators. These usages have not been verified. In fact, two late production 1968 manual cars with V01 have been documented with the 21" 3017132 ZB radiator. This would suggest the radiator size did change to 21" on these applications, but that GM documention is incorrect on which radiator was used.

Radiator Shroud Usage and Part Numbers

Radiator Cooling Fans

The temperature-controlled clutch fan was also available as option K02 on the hydraulic-lifter engines for $15, but only 4712 1967-69 Camaros were ordered with this option. Air conditioning (RPO C60) included the K02 clutch fan as part of the AC package. The V01 HD radiator option did not affect the fan usage.

Out of 400,000 non-AC V8 cars that could have the optional clutch fan ordered, only 1% of them had the option. Even if most of these clutch fans were installed on non-L78 SS cars (not very likely), under 5% of those SS cars would have them. So yes, your SS350 or SS396 (325hp or 350hp), if without AC, likely came with the standard four-blade fixed fan.

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". In 1969, as part of the V8 engine layout standardization, the water pump was changed to the long design and the water pump bolt circle diameter was changed to 2.30".

Fixed (Non-Clutched) Four-Bladed Fans

There were a number of different length spacers to mount the fixed four-blade fan to the waterpump, as shown in the table below. The lengths noted are the spacer length and exclude the fan locator / pilot. The 67-68 fan had a flat center whereas the 69 fan had the ribs continuing through the center section, which required the longer locator nib on the 69 spacers.

3839282 Four-Bladed Fan 67-68

Four-Bladed Fan Spacer Part Numbers Year Application Part Number Length (inch) 67-68 6 cyl. 3876828 2-9/32 67 V8 (exc. 396) 3814241 1-15/16 68 V8 (exc. 396) 3857041 1-17/32 67-68 396 3857042 1-9/32 69 6 cyl. 3927794 1-1/2 69 V8 3927792 1

3876828 Spacer for Fixed Fan

3927792 Spacer for Fixed Fan

69 3927791 Four-Bladed Fixed Fan

396 3947890 Four-Bladed Fixed Fan

Clutch Fans

A variable in the clutch applications is the distance of the fan mounting surface to the waterpump mounting surface distance. This distance is normally different between small block and big block applications with the big block clutch having a shorter shaft to properly position the fan fore-aft relative to the fan shroud. There were at least three different clutch suppliers. It is believe that the redline of the engine was a factor in which clutch was used on an engine. Fan clutches often have the date (Julian date and year) and part number stamped on the waterpump mounting flange. Eaton fan clutches have "Eaton", the broadcast code, and the date with a letter for the month, numbers for the day, and a letter for the year. E14J is May 14, 69.

In 1967 and 1968, the clutch fan was 18 inches in diameter, most had five blades (there was limited usage of a seven blade fan, see below), and came in two types:

Fan for AC or K02 cars

For 1967 cars with hydraulic lifter engines with AC or K02, the 3789562 fan or the 912239 fan was installed. For 1968 cars with hydraulic lifter engines with AC or K02 (except 1968 L34/L35), the 3789562 fan or the 3931002 fan was installed. The 3931002 is a seven blade fan with limited observed usage on Camaros; it has so far been found on some LF7 (327/210hp) cars with air conditioning. All three fans have a 3-inch diameter clutch-to-fan attachment bolt circle.

Three different fan clutch part numbers are listed in the AIM as having been used with these fans, all having the 3-inch diameter bolt circle. For 67: 3916139 and 3916140. For 68: 3916139, 3916140, and 5329100. Fan clutch 5389475 (with a 6" OD) has also been observed on 68 Camaros.

Fan for L78 and Z28 and 1968 L34/L35 with K02

The 3871276 fan was used on the 1967 and 1968 Z28 and L78, as well as 1968 L34/L35 with K02. The bolt circle diameter for the clutch-to-fan attachment was 3.25-inch. It thus required a different clutch unit than the fan clutches used with the AC or K02 hydraulic lifter engines.

The 67-68 Z28 and the 68 396 cars used the 3927103 Switzer-supplied clutch unit. The parts manuals list the 67 L78 clutch as 3916141, but this usage has not been verified.

Five-Bladed Fans for 67-68
(Note the difference in the center hole diameter.)

3789562 fan		3871276 fan

In 1969, the clutched fan changed to a seven-blade design (still 18 inches in diameter) with aluminum fan blades. Cars with AC or K02 received the same fans as the 1969 Z28 and L78/COPO cars. There were two manufacturers of this fan and a mid-year fan pitch change (2 to 2.25"), yielding four variants of this fan.

• The 3937779 fan had a 2" pitch and was made by Schwitzer. It was used early in the 69 production year (until approximately November of 68) and has the part number and month / year stamped on the fan blades.
• The 3947772 fan replaced the 779 fan and had a 2.25" pitch. It was produced by Schwitzer and was used during the remainder of the production year (and through the early 70's) and has the part number and month / year stamped on the fan blades.
• There were two versions of an 'unstamped' fan made by Hayes-Albion. 3947838 was the earlier 2" pitch version and 3956684 was the later 2.25" pitch version. The fans are normally stamped H and FRONT, but no part numbers or dates are stamped on the fans. They are similar to the 772 and 779 fans but with minor design differences (specifically: the design of the center section and details of fan blade rivet attachment).

From what has been observed on original cars, the 3947772 fan and the unstamped fan were used interchangeably and with approximately equal usage. As noted above, the 3937779 fan was only used on early 69 cars.

3947772 Seven-Bladed Fan for 69

'Unstamped' Fan		3937779 Fan Close-up

In 1969, 3 different fan clutches were used for C60 (AC) and RPO K02 cars (except 396). The AIM lists the part numbers as 3937780, 3937782, and 4939899; the service part was 3937781. These clutches have been observed to be Delco clutches, stamped with the broadcast code of CH. The 4939899 clutch has a mounting face to mounting face distance of 1.8" and has an outside diameter of 6 inches.

The L35/L34 396 cars with C60 or K02 used a 3946049 clutch with a ink-stamped broadcast code of CI. (The AIM shows this clutch was also used for 350 ci engines, but that is not what has been observed in cars. It may have also been used with solid lifter cars.)

The L78/COPO used part number 3946050 (stamped CZ) and the Z28 used 3946804 (stamped CV), both were Eaton-supplied units with an OD of 7 1/4".

1968 Z28 Fan Clutch		1969 Delco Fan Clutch		1969 Eaton Fan Clutch (CZ code)

Acknowledgments

You can help improve future revisions of this report. We would appreciate verification of unconfirmed radiator usages via data from original radiators and cars (or via broadcast sheets). We also would appreciate digital photos of original radiator tags. The tank codes on the 1968-1969 tags will help verify the radiator tank usages.

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