Hello CF Members:

I am relatively new here and need some help. I have looked extensively (without success) in an effort to identify the correct part # for the original Harrison radiator installed in my L48 1979 Corvette with MT and A/C. The '78/'79 NCRS judging manual indicates that there was a tag attached to the passenger side header tank that had a two-letter broadcast code as well as the stamped/embossed part#. I've also been told that an original Harrison radiator has an embossed part# on the lower shoulder of the radiator frame (passenger side) that is not exposed, though you can feel it with your fingers. Anyway, because the judging manual only contains general information I was hoping that the local experts here might enlighten me. I want to find an original radiator for the replacement unit that's presently in my car and your help in identifying the correct one will be greatly appreciated. Thanks.

 

I looked at my archive of 78-79 buildsheets to determine what would have been installed on a 79 Corvette with your options.

Unless your L48, M20, C60 was equipped with the heavy-duty radiator, your code more than likely was MK, or the base radiator. The code ML was installed on L48s when configured with either FE7 (heavy-duty suspension) or V01, heavy-duty radiator.

Finding an original radiator for that 78 will be no small task. Perhaps better to find a radiator shop that can clean and repair than replace.

The 1978 AIM (assembly instruction manual) only calls out radiator assemblies, not the specific part number.

Hope this helps!

 

Thanks very much for the information. Your mention of the build sheet was helpful (I have the original build sheet for my car) because it didn't occur to me that the code would be listed there. I checked this morning and found that the radiator code was actually 'MJ'. For what it's worth, V01 does not appear on the build sheet so the car did not come with a heavy-duty radiator.

The original (1979) radiator was replaced in 1997 and I wasn't thinking about NCRS judging 20 years ago; so, unfortunately, I didn't save it. I agree that finding a 40 year-old radiator will be challenging, but I have the benefit of some time. Hopefully other CF members will see my post and be able to help me out. Thanks again.

 

Phil, I bought a new Harrison radiator from GM for my '73 manual trans, Corvette in 1991. I was taking the car to Hawaii and didn't want to encounter any heating issues while there so did it primarily as a preventative measure.

About 10 years later when back in CONUS, I decided to do a frame off restoration on it and completely took the car apart. Since I had previously bought a new Harrison radiator I believed it would be fine with just a clean up and repaint. As I was cleaning the radiator I started by blowing air through the fins to dislodge any debris that might be in there. To my surprise the fins just disintegrated and began to blow away. The tanks and core inside looked great and none of the tubes leaked.

GM no longer made a radiator that fit my car, so I contacted Tom DeWitt. At that time he did not offer a complete replacement for the '73. He did however have a new core that he could sell me that would fit my radiator. I bought the new core and took it and my Harrison radiator to our local radiator repair shop where they installed my original tanks on the new core. The radiator has performed flawlessly since then, and it looks completely original.

You might want to check with DeWitts to see if he can help. Great folks to deal with and they produce a superior product in my opinion. I also believe that they will be at Carlisle and they typically offer show special pricing.

Good luck... GUSTO

 

GUSTO:

Thanks for taking the time to weigh in. I spoke to a couple of '78 Pace Car owners at the recent National Meet in Rhode Island and they did the same thing you did, i.e., installed the original tanks on a new core. They maintained originality while effectively getting a new radiator. My mistake was not keeping the original radiator 20 years ago, so I have to find one that can be re-cored. I hadn't thought to contact Tom DeWitt because I figured that he just sold replacement units. Maybe he has or can find me an original 'MJ' radiator. Thanks again.

Phil

 

I'm curious and would like to see a scan of your buildsheet, if you don't mind sharing. Post here or send to hunt4cleanair@earthlink.net

 

According to my 1980 Corvette parts book, the 79 code MJ radiator was part number 3035558. This was the 1 1/2" inlet, 79 first design radiator, that was also used in 76-78 Corvettes. The second design 79 radiators have a 1 1/4" inlet.

I have a couple old Harrison's at the shop. I'll look when I get in, to see what I have, but I think they may be the later 1 1/4" inlet ones.

 

Tom, I think you may have posted this on C3 Build Sheets a while back. It was a great article, so I down loaded it and have referred to it many times. There's a good deal of info regarding radiators on page 4.
http://www.hunt4cleanair.net/Articles/C3BuildSheets.pdf

Thanks and good luck... GUSTO

 

Thanks for the Part# information. In my search for a 1979 radiator I've seen reference to different inlet sizes, so knowing that the 'MJ' code has a 1 1/2" inlet is very helpful. I'm curious about first design versus second design because my car was a June 1979 build, which is late in the model year. It was about number 39,000 of 53,000 cars built. Anyway, please let me know if any of the radiators in your shop are a fit for my car. Thanks again.

Phil

 

Not sure if you already found this, or if it's even accurate, but it lists radiator codes for 79....

https://www.corvetteforum.com/forums...stock-and.html

According to this, both MK and MJ were 1 1/2" inlet, and the 1 1/4" inlets had codes starting with 'F'?

 

Just to clarify, when referring to the size of the inlet, we mean the neck (capside), given the cap is the same vs. the hose inlet? The GM# 3035558 was also used in 1978 but carried a broadcast code of ML...as noted by Pete79L82 in this 2003 post.

Thanks to Bradley who reached back to 2003 to provide us a link to this data by Pete79L82

I need a lesson on radiator structure so what does "core" refer to given above Corvettes included either a 3 core or 4 core design?

Gusto reminded me of an article published in the Restorer about buildsheets and I mentioned GM# 3035856 as the heavy-duty radiator (V01) called out in 1978 with the broadcast code MK.

Most interesting thread!

 

According to my 1980 Corvette Chassis and Body Parts Catalog, 3035558 was used in 78, but it carried the code "MJ", not "ML". The parts book lists part number 3035856 as radiator code "ML".

Here's the breakdown of the radiator usage from 76-79, starting winth the 76 2nd design (the same radiators were used from 76-79).

3035558
1976 - 350, except hi-performance (L-82), 2nd design 76, code MK, 1 1/2" inlet.

1976 - 350, w/hi-performance (L-82) w/o air conditioning, 2nd design 76, code MK, 1 1/2" inlet.

77-79 - 350, except HD radiator, code MK & MJ, 1 1/2" inlet.

77-78 - 350, w/air conditioning, except hi-performance (L-82), code MK, 1 1/2" inlet.

3035856
1976 - 350, w/hi-performance (L-82) & air conditioning, 2nd design 76, code ML, 1 1/2" inlet.

77-79 - 350, w/spl hi-performance (L-82) & air conditioning, 1st design 1979, code ML, 1 1/2" inlet.

77-79 - 350, w/HD radiator (V01), 1st design 1979, code ML, 1 1/2" inlet.

3043087
79 - 350, w/hi-performance (L-82) & air conditioning, 2nd design 79, code FW, 1 1/4" inlet.

79 - 350, w/HD radiator (V01), 2nd design 79, code FW, 1 1/4" inlet.

3043083
79 - 350, except HD radiator (V01), codes FP & FR, 1 1/4" inlet. * This radiator doen't carry the note in the parts book, that it was 79 2nd design, but having the smaller 1 1/4" inlet, would make it a 79 2nd design radiator.

 

3 and 4 refer to the number of rows of cooling tubes within the radiators core. It describes whether the rows run 2 deep, 3 deep or 4 deep, if that helps.

 

The core is that portion of the radiator that actually performs the cooling. It contains the tubes that coolant flows through and the fins that surround the tubes to aide in cooling. The "tanks" are typically bonded onto the ends of the core. They can be soldered, epoxied or in the case of modern radiators with composite tanks, clamped onto the core.


This is what a a clogged 4 row radiator core next to a new one would look like.


Here is what a 3 row, in this case a brass/cooper core, would look like.


Good luck... GUSTO

 

I got a chance to look at the Harrison radiators I have here, and they're for automatics, so I didn't even try to identify them. Sorry.

 

Just curious - none of the radiators you listed above specify 4-spd vs automatics. Did the 4 speed cars actually come with radiators that didn't have the tranny cooler in them, or were the holes just plugged?

 

Good stuff and illustrates how more rows adds to cooling capacity. As you describe, then the tanks bond to the ends so the pressure forces coolant through the core from top to bottom to the other side where it moves through the block and so forth.

So for us late C3 guys, it sounds like we should hang onto an original radiator to preserve the tanks while replacing the core. And we could slip in a few extra rows without those pesky NCRS judges knowing!

 

So explain why with heavy-duty we go to a 1 1/4 inch neck vs. the 1 1/2 inch?

 

Bradley:

Relative to the radiators found in 4-speeds vs. Automatics, the Judging Manual states the following: "All radiators have fittings for automatic transmission cooling lines. Vehicles equipped with manual transmissions will have plugs in these fittings". So, the same radiators were used for both transmission types with the noted modification for MT cars.

Phil

 

GB:

Thanks for checking. The judging manual states that the same radiators were used for both AT and MT cars; however, the fittings for the automatic transmission cooling lines were plugged on manual transmission cars. So, unless there's something special about the plugs, I may be able to use one of your AT radiators after all. Can I impose on you to check the broadcast codes to see if there's an 'MJ' among them? Thanks for your help.

Phil