I tried to have an original 4 core Harrison radiator re-cored for a customer's '78 and no radiator shops around here would touch it. I think it's a dying trade.

 

Here's a different approach to cleaning out your radiator. Cheap and easy to dispose of the waste when done. I did this on my 1956 Ford farm tractor that had never had the radiator out. Did just fine and is still holding strong. Remove your radiator. Plug up the upper or lower outlet. Stand the radiator up and fill it up with White Vinegar. You can buy it by the gallon and it's cheap. Let the radiator stand for maybe 48 hours then empty and flush out with clean water. Just pour the vinegar down the drain and you're done. I let it run off the driveway and into the lawn. Didn't hurt a thing. If it doesn't work, you can always spend the $500.00 on a new one!
Duane

 

And I want to say, that what I posted in this thread was just reflecting my past experiences, not second guessing any other Members. I learn from you guys every day. Thank you, mike...

 

 

I just did a copper/brass one for my 86 C10 and purchased a copper/brass core for my 70 LS5 w/AC (from Dewitts). I'll be re-using the original numbers matching end tanks. They don't manufacture the copper/brass cores by the way. They drop ship them from another vendor.

Everybody is selling the offshore aluminum units with the plastic end tanks. Haven't found one that fits right yet (non-Corvette).

On the copper/brass units, all you have to do is use a propane torch to melt the solder along the tank lip and blow it out with compressed air (wear safety glasses). It makes a huge mess but it works fine. Then clean up the tank flange and re-tin it. Bring the heat in from the tank side and don't overheat... just enough to melt the solder. Melt about 1 inch and blow it out, repeat. After the solder is all removed, the tank might still be stuck on the core. Re-heat it at those spots and it gradually releases. The cores come pre-tinned. Drop the tanks on the new core & fill in the void with fresh solder... again bring the heat in from the core side, don't over-heat. Just be careful not to hit the core tubes with the heat and you'll do just fine. I've done a lot of these in the past. No big deal.

Not sure how the OEM aluminum ones are manufactured. I can see how that can be tough since you can't solder aluminum. I have welded aluminum with a product called "Lumiweld" and oxy/acytelene but I doubt that can be used on a radiator. It was very hard to control the heat on aluminum starter noses and intakes. Plus Lumiweld relies on gravity to float the oxide layer to the top for bonding below the puddle. Can't see doing that on a radiator. Would be interesting to hear how the OEM aluminum ones are made. I'm sure Dewitts could tell us.

 

My '74 started to run hot on the highway a while back. I finally figured it was a timing issue. One of the studs that the advance weights pivot on had broken loose, and the timing was way off at speed.
Check your distributor first. It's easier than pulling the $%^& radiator and shroud.

 

Just out of curiousity, assuming your timing was far too advanced, did you happen to notice any knocking?

 

Great point.

 

It sounds like a joke, but it's true. I've heard people refer to it as the "Corvette tax".

Scott

 

Dunno exactly where the timing was at speed. It may have locked up at idle without advancing at all. I just knew it was not right.
My car NEVER pings. It runs fine on regular gas. Edelbrock Performer 2102 cam, 9 1/4 to one compression. I run it at 12 degrees initial, 32 degrees total mechanical at maybe 2600RPM, plus 15 degrees vacuum.