Brass & Copper Harrison Tank Dates

[James G.]

Having been paid to do numerous pre-purchase inspections of GM muscle cars and not having been a NCRS member when I purchased my corvette I assessed the vehicle as I though I were being paid by a customer for an evaluation. Numbers and data. Many years I had learned that the Harrison manufactured brass passenger side tanks on Camaro's, Firebirds, Nova's, Chevelle's GTO's and 442's all had manufacturing dates in the following format:
A
2

A-L month
1-5 Week - though I have never seen a 5 in my life.

When I did my prepurchase inspection of my fairly unmolested 1971 LT1 I of course looked for a rad date in the same spot. F1 JUNE 1st week. Car built July 16th.

I really though nothing more of it... Until reading countless posts and articles stating that the LT1 rads were not dated, then I second guessed myself and thought maybe I am crazy.

So today I cleaned the area off and got GOOD photos.
These dates are embossed into the tank on a low rib, sometimes the embossing is not deep and they are VERY difficult to read ESPECIALLY if there are more than one coat of paint.
For example... Originally I thought that the date was F4 (still good for a 2nd week July build)... after cleaning it well it is F1.
These dates can be extremely difficult to make out especially with the radiator in the car.

[Tom R.]

Re: Brass & Copper Harrison Tank Dates

Hey James

Your post was brought to our attention by a member of the 1973-74 judging manual revision team. We are working to reconcile the tank date code with an assembly tag that includes the broadcast code followed by a single digit for the year. Your post describing that the embossed date code on the tank is month/week reconciles with the assembly tag. I've posted a number of illustrations for your review. We know from the buildsheet that the two letter code represents the broadcast code printed on the buildsheet and used on the assembly tag (e.g., MK, MG, etc.)

From a 1978 November 10th built car


A 1974 November 10th built car



A 1973 December 13th built car

[Mike E.]

Re: Brass & Copper Harrison Tank Dates

Tom,
I am not sure that the third character on the assembly tag is for a year. At least that was not the case in 70-72. Those tags (MI, MK, MJ) in the 70-72 time frame all ended with a 9, and I am sure they did not build enough radiators in 69 to last all the way through 72. The 9 was embossed at the same time and manner and size as the two-letter code, while the pic you have of the MK7 has the 7 debossed. That definitely is a departure from how they did the earlier ones.

[Patrick H.]

Re: Brass & Copper Harrison Tank Dates

Tom,
I am not sure that the third character on the assembly tag is for a year. At least that was not the case in 70-72. Those tags (MI, MK, MJ) in the 70-72 time frame all ended with a 9, and I am sure they did not build enough radiators in 69 to last all the way through 72. The 9 was embossed at the same time and manner and size as the two-letter code, while the pic you have of the MK7 has the 7 debossed. That definitely is a departure from how they did the earlier ones.

Mike,

This has been my thought regarding the assembly tag as well.

Patrick

[Tom R.]

Re: Brass & Copper Harrison Tank Dates

Interesting. If you zoom in on the MK7 photo, you'll see the tag includes the part number that reconciles with the AIM, debossed as well.

[Mike E.]

Re: Brass & Copper Harrison Tank Dates

Interesting. If you zoom in on the MK7 photo, you'll see the tag includes the part number that reconciles with the AIM, debossed as well.

The 70-72 tags have the 7-digit part number debossed also.

[James G.]

Re: Brass & Copper Harrison Tank Dates

I had originally thought that the embossed tank numeral was for the week...
HOWEVER after the above illustrations I now believe the Numeral is for the YEAR.

The Alpha is the Month the Numeral is the year.

My LT1 built July 1971 has a F1 June 1971
My Brother's 1973 Z28 built Jan 1973 has L2 December 1972

I had not seen numerals on any of my 68 or 69 model year Radiators only alpha characters.
My 2 1969 Z's had singular alpha D and J characters and my 68 GTO built Oct of 1967 has only a single (I) alpha for month.

Harrison must have began with the numerals representing year after 1969.

[Tom R.]

Re: Brass & Copper Harrison Tank Dates

I had originally thought that the embossed tank numeral was for the week...
HOWEVER after the above illustrations I now believe the Numeral is for the YEAR.

And the number on the tag that follows the broadcast code?

[Tom R.]

Re: Brass & Copper Harrison Tank Dates

A member of our 73-74 team sent me these photos of his 1974 I30 built car with radiator M 3 codes. Had to scratch my head and then concluded, Harrison dropped the code I for the month and used M for the twelfth month. Thus, this December 1973 radiator assembly was installed in an April 30, 1974 Corvette. The radiator was rebuilt and the tag not returned.