C1 RADIATOR

**Jack H.** · March 2, 2003, 01:03 PM

Re: C1 RADIATOR

The 61-2 Judging Guide seems pretty clear on the issue. The 1st 192 base engine cars built in '61 used '60 style copper radiators (3141674) as carry over. Early HP engines used aluminum radiator (3151116) for the first 1700 units that were carry over from '60 production. The JG book recites a Chevrolet Advanced Information Bulletin 60-16, dated 9/60 to document.

**Karl #35089** · March 2, 2003, 02:31 PM

Re: C1 RADIATOR

I have an early 230 with a top tank. Maybe I looked until I found the answer I was looking for, but... in researching this I found the following:

"Early 1961 Radiators"
Posted By: Dale Pearman
Date: 10/7/2001 at 23:02:55
"Early 1961 Radiators" By:Dale Pearman
QUESTION
I own a 1961 Corvette, VIN# 10867S10XXXX. I would like to know which type of radiator was the original equipment for my Corvette. Was it the top tank style or did it have an expansion tank? Also, were the radiators dated? I appreciate you time. John Doe.
ANSWER
This perennial question is generally unanswerable. A great deal of insight may be gained however, through an understanding of the events in production as OBSERVED on unmolested Corvettes coupled with Harrison and General Motors documentation. This "gray" area in 1961 production is limited to the first 2,500 or so Corvettes of that model year. Your sequence in production is XXXX.
HISTORY
In 1960 production the Harrison aluminum radiator was introduced as part number 3147516 and appeared with an integral top mounted expansion tank. The first tanks were without reinforcing gussets along the top tank and without the plastic view plug. The drain petcock was directly attached to he radiator and a 6 1/2 inch hose was attached to the petcock. The ID tag was installed on the top tank such that is was upside-down when viewed from the engine compartment. The Harrison release date for this first aluminum cross-flow was 4/11/59.
One 7/21/59 the ID tag was reversed for easier reading. Five reinforcing gussets were added to the top tank on 10/26/59. A plastic viewing plug with "Clover" embossed along the circumference was added to the top tank on 1/7/60. This was the same plug used on milk bottles of the era.
Harrison Top Tank radiator #3151116 was introduced on 6/14/60. This radiator was identical to the 3147516 except for a drain revision. An aluminum nipple was attached to the radiator drain hole and the petcock to the nipple. The rubber hose was eliminated.
The ID tags for both radiators contained a stamped part number and date code. The date code was by year and month in two characters. i.e., 1A. (January 1961) they were attached to the top tank in the center of the tank with two round head aluminum slot-head screws. All Harrison radiators were unpainted raw aluminum until 11/21/60. (1961 production)
The Harrison #3150916 cross-flow requiring a separate expansion tank, (3151016), was released on 6/10/60. This design was later revised to eliminate a square casting boss on the top of the inlet neck for 1962 production.
PRODUCTION
The 1960 model Corvette generally appeared with copper-brass radiators on all hydraulic lifter engines and top tanks on all solid lifter engines., At the end of 1960 production, a quantity of copper-brass radiators, 3151116 aluminum, and perhaps a few early 3147516 aluminum radiators of various revisions were left in inventory at St. Louis. The new 3151916 radiators (separate expansion tanks) were arriving at the assembly line was well. (unpainted).
It is important to note that the core supports for top tank radiators were different from those designed to accommodate the newer 3151916 radiators or those designed to accommodate copper-brass radiators. The copper support was 3774856 while the 916 support was part number 3786902. The part number for top tank supports is 3772854. Also, a revised hood was designed for the newer radiators in order to clear the tanks. The 61-62 hood is significantly redesigned. These parts were NOT interchangeable. A top tank radiator required a top tank hood. A 61-62 (916) radiator required a 61-62 hood. These facts were ignored in the following directive from Chevrolet Advanced Information Bulletin 60-16 dated September of 1960.
"Approximately 1,700 early production 1961 Corvettes will be built with 1960 type radiator assemblies until 1961 aluminum cross-flow radiators become available. 192 copper radiators will be used on Corvettes with base equipment engines. 1,500 1960 type aluminum cross-flow radiators will be used on hi-performance Corvettes and also on the units with the base engine after the supply of copper radiators is exhausted. Both the above radiators are equipped with an extended drain assembly necessary for draining accessibility on 1961 Corvette" (GM Chev. Bulletin 60-16).
Our observations of unmolested, unrestored early 1961 Corvettes indicate that the above bulletin was DISREGARDED on the assembly line. We have seen fuel injected 961 Corvettes as well as 270 HP versions with COPPER-BRASS radiators. We have also seen hydraulic lifter Corvettes with the top tank aluminum versions. Also, this random radiator usage was extended to as late as serial number 2,500 (approx.) I believe that radiator usage was determined by hood and core support availability. Inventory control was very poor at the St. Louis assembly line in the '60's. "Last in" might have been "first out" and "first in" may have lingered on the back of the shelves for sometime before use. It may have happened that at serial number 2,400 a top tank core support was used and a top tank radiator was found even though the model being assembled was a 230 HP 1961 Corvette. Also, several Corvettes with the 1,700 units were made with the 916 radiator requiring a separate expansion tank. Unused radiators, after early hood and core supports were used up, may have been returned to the GM Parts Division for over-the-counter sale.
Most of the RESTORED early 1961 Corvettes follow the GM bulletin because that bulletin has become an absolute in judging manuals. Restorers alter history in order to escape point deductions. A GOOD judge will not allow absolutes in judging and will instead ask him/her self, "How could this configuration have occurred?" There are NO absolutes in Corvette production. This fact is one of many that make our hobby so exciting.
CONCLUSION
My opinion is the "ANYTHING GOES"in the radiator department for 1961 Corvette S/N XXX. You might discover clues regarding the original configuration by examining the hood and core support if the are original. Good Luck!
Respectfully,
Dale Pearman

**Ed Jennings** · March 2, 2003, 03:37 PM

Re: C1 RADIATOR

I have an aquaintence here in town with a 61 fuelie built in OCT 60, VIN 23XX, which has an original top tank radiatror.

C1 RADIATOR

C1 RADIATOR

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