Replacing my Coolant Hoses, Thermostat, and Heater Core.

[bd]

That's a 3-row core; 3 tubes side-by-side.

[Henry]

Hi Spool:
Radiator: from your measurements and photo, it appears you have a 3-row OEM style copper/brass radiator. So take that baby out and have a radiator shop give it a clean and whatever little repairs it may need (brazing leak points). If it cant be cleaned 100% then splurge on a new OEM style radiator of same size and copper/brass. Check pricing by comparing prices of car parts stores (Autozone etc) with catalog guys (Brothers etc) and what the radiator shop can get from their supplier. Sounds like your truck came with the same 3-row as my 76 C-20.

Fan spacer: no, you dont absolutely have to have it...your truck runs fine right now without it. But, it will actually help pull air through the radiator better if it is completely under the shroud...and give you a safety factor for your fingers when working on the engine when it is running. I have seen the Chevy small block spacers for sale at car parts stores such as Autozone and OReillys...Just measure how much the fan needs to move forward to be just under the shroud and this is the thickness of spacer you need.

All the parts you need to replace for the cooling system and heater can be purchased most economically at the local parts stores and they probably have pretty good warranties and the quality should be OK. Some parts like your overflow tank and radiator isolators are not so common and you can get this from a couple of specialty Chevy truck catalog suppliers.

This is going to be a huge job with the truck out of action for a while...depending on how much time you have to work on it. If you trust the quality of work your radiator shop does, you may inquire how much they would charge to do the whole job for you. But it still would be cheaper to do it yourself if you have the time and enjoy this kind of mechanic work...yes it will be a dirty job...way more than that distributor you replaced a few months ago.
Regards,
Henry
469-200-4253

[Spool]

Thanks guys.
I truly appreciate your time.

I have a question/thoughts about metals and electrolysis.

I noticed most of the radiator market is aluminum these days.
BD, you mentioned aluminum was prone to electrolysis.
Is Brass/Copper less prone to electrolysis?

I'm finding that genera flushes are $100-$150.
For that cost, I'd rather just go for a replacement.
Ideally, I'd like to stay away from aluminum and stay OEM;
I don't particularly like the aluminum look either.

Thus far, I was able to find autozone with a duralast for
$200 (Which I need to call to clarify it's fit beyond "vehicle specific" and speedway for about $360 which I need to check fins per inch.
https://www.speedwaymotors.com/1973-87-Chevy-Pickup-and-Blazer-3-Row-Radiator-OEM-Replacement,73842.html

[Henry]

Hi Spool:
Electrolysis: If you google a galvanic series table for metals on the internet, you will see that aluminum is highly anodic (wants to get eaten up). Cast iron (your engine block) is less so, and copper alloys are even less so. So when you put aluminum together with metals that are farther away on the table (more cathodic) with a electrolyte (your cooling water), the aluminum atoms will start to lose electrons and break down. Cast iron and copper are about the same distance apart on the table as cast iron/aluminum, but since both closer to the center of the table they are not as reactive as cast iron/aluminum pairing. In fact, the cast iron becomes the anodic couple in cast iron/copper alloy pair...since the cast iron is so huge and massive, it will take a long time to break down not to mention it is simply not that reactive. Cast iron does oxidize(rust) by itself in air quite readily, but this is a different phenomenon than rusting by electrolysis.

Let me know if you decide to take on the heater core/radiator job yourself and I can draft a step by step to make the job easier. To me, the hardest part of the job is disposing of the antifreeze responsibly...fortunately in my city I have a hazardous chemical disposal center that takes anti-freeze for free...something you should check into.

Regards,
Henry

[Spool]

Thank you, Henry.
I would very much appreciate any help in the process; I'm very excited to tackle this and learn from it. Ideally, I'll have all my parts on hand before starting.

Here's an interesting page I found on Aluminum Vs Copper/Brass.
I'm very appreciative of all the help and info on the forum, but can't seem to
grasp a firm conclusion on radiator material with such an abundance of opinions on the web. (Per usual)

I had a buddy mention that he believes Electrolysis would only occur with straight water in the system opposed to a 50/50 water/coolant. Thoughts?

EDIT***
I didn't include the mentioned link:
https://www.cgj.com/2013/07/16/aluminum-vs-copper-brass-radiator-final-thoughts/



At this point, for me it's price.
So I'll be shopping around quite a bit the next few days and sharing my finds on the forum.

[Henry]

Hi Spool:
The reason that there is so much discussion on the net on copper/bronze vs aluminum is that the performance on both is adequate. There are so many variables to make a direct head to head comparison that it is impossible unless some engineers undertake an experiment and publish the results in some technical rag....and then the results will indicate that one is better than another on certain technical factors and another is better on other technical factors by  small margins that are really insignificant for the daily driver. Unless you can get a significant price advantage on an aluminum radiator, I would stick to the OEM design for ease of fit. One thing I can tell you for sure: aluminum radiators are not a performance technological improvement over copper/brass radiators... automotive design engineers have always known about them...it is all about the money...aluminum is cheaper than copper now.

Gimme a day or two and I can make a step by step for you in Word...it should help you in the process.

Regards,
Henry 

[Spool]

Thank you, Henry. I truly appreciate your help.

I'd like to share some finds I found on the web this afternoon to seek advice or red flags by others on the forum.

I found it a little difficult, or rather I did find many options in seeking out a Radiator that fit the 19x28'' core dimensions, let alone Brass/Copper over Aluminum.

I also am leaning more towards the 4-row avenue as a basic upgrade in a proactive measure for future AC/Towing etc despite what we already discussed; unless however, someone would like to correct me in saying/confirming that I am absolutely not currently in need of a 4row radiator even with 100 degree temps, 60 mile rides, future AC and potential towing. (I'm just trying to be proactive and settle my mind on future warm days when I do need to drive far.)

Here are the radiators I found:
https://www.summitracing.com/parts/sum-382018/overview/year/1973/make/chevrolet/model/c20-pickup
https://www.summitracing.com/parts/sum-384030/overview/year/1973/make/chevrolet/model/c20-pickup
http://www.championradiators.com/4-row-Chevy-C/K-radiator-19-1973-1991
https://www.npdlink.com/product/radiator-replacement-style-brass-tanks-and-copper-core/194441/100299
https://www.speedwaymotors.com/1973-87-Chevy-Pickup-and-Blazer-4-Row-Radiator-OEM-Replacement,73843.html

The last one from speedway seems to be a perfect fit, but I'm having trouble justifying a $500rad.
They do sell a similar $400 3row rad.

Other than that, I'd have to confirm fins per inch.

Any tips or thoughts anyone?
I've reattached an aerial over my belt and shroud to show available room for a thicker core.

Thanks in advance.

[75gmck25]

You may have already moved on and replaced parts, but I'll provide a description of what has worked well for me.  I try to buy good parts, but not get too expensive.

Stewart stage 1 high flow water pump
Stewart 195 degree high flow thermostat
Hayden severe duty fan clutch and stock metal fan; full stock shroud
3 row copper radiator (initially), now 3 row aluminum radiator (Champion CC161 from Jegs)

I swapped in the aluminum radiator a few weeks ago because I accidently punched a hole in the old copper radiator.  It turned out to be a good upgrade that works much better under load than the old copper radiator did.  The new radiator is the Champion 166-CC161, priced at $235.

While charging the A/C last week it was 90 degrees outside, and I had the truck idling for at least an hour while I tweaked the system and checked things (it goes slowly with small R134a cans).    Based on my Summit digital temp gauge, with sender in the passenger side head, the engine was running  between 187 and 190 degrees the entire time.  I then took it out on the highway and ran it around for a while with the A/C on, but still never saw the temp go above 192 degrees.   I assume my 195 degree thermostat may be opening a little early.  YMMV.

Bruce