C2 1966 Big Block Radiator Identification

[Mark P.]

My '66 big block has a Harrison copper radiator that is embossed (near the cap) but the rectangular cut outs don't necessarily fit the description in the judges guide. Any idea on if this might be a service replacement or what it is? If it isn't correct, where could I find one? I looked at DeWitts and it doesn't appear that they have a completely accurate reproduction, just a suitable aluminum replacement. Any thoughts on what judging points ding I would get for the replacement, either from DeWitts or the one I have now?

Thanks,
Mark

[Joe L.]

Re: C2 1966 Big Block Radiator Identification

Mark-----

I have no way of knowing if the radiator on your car is original, or not. The fact that it's embossed "Harrison" is a good sign, though. Much later Harrison SERVICE radiators (which are definitely incorrect) don't have the Harrison embossments. On the other hand, earlier Harrison SERVICE radiators are usually identical or near identical to the originals.

Also, DeWitts does manufacture a complete copper/brass restoration radiator for your application. This is absolutely the best piece available on the market today. It's correct as to both tank and core configuration and with respect to the "cut-outs" on the top reinforcement. Is it 100% correct "in the eyes of all"? That I could not tell you.

By the way, if you're interested in the best cooling rather than 100% originality, the way to go is the DeWitts "direct fit" aluminum replacement. This radiator is GENERALLY configured as-original but it will cool a LOT better than the original or the reproduction. It won't fool any judges, but you'll appreciate it when you're driving the car in cooling-demanding situations. The direct fit aluminum has about 25% greater cooling capacity than an original-type radiator.

[Mark P.]

Re: C2 1966 Big Block Radiator Identification

Thanks, Joe. The direct fit option would be helpful for the cooling capability if nothing else. It runs pretty hot if I even think about slowing down or idling in traffic. Mine is not a "parade car" for that very reason. Those 95-100 degree days in Utah are tough on any car, especially big block mid-year Corvettes. I'm still concerned about taking a huge hit on judging and couldn't see a direct correlation in their restoration line to a '66 big block...only for '65 396 or later L-88's.

I'll check a little further and decide what I want/need to do.

Thanks again,
Mark

[Joe L.]

Re: C2 1966 Big Block Radiator Identification

Mark-----

You need to look under "copper brass" section of their web-site for the restoration 66 big block radiator. It's not under the "restoration" section, since DeWitts specializes in aluminum restoration radiators for 1960-72 Corvette applications and their restoration section is limited to that type. But, they do have the restoration copper brass radiators for most 66-68 Corvette big block applications as well as some 1968 small block applications.

They don't currently have the 1969-72 copper brass radiators, though.

Their "direct fit" aluminum replacements ought to be a "powerful incentive" for folks with big blocks that DRIVE their cars. The extra cooling capacity is hard to pass up. In fact, their "direct fit" replacements for the GM #3018571 and GM #3019190 used for most 69-72 big blocks (except L-88, ZL-1, and ZR-2 applications with manual transmission) have a higher cooling capacity than ANY radiator ever originally installed in ANY 1953 through 2007 Corvette. In fact, they're about 25% higher than any original 1953-2007 Corvette radiator.

[Chris Patrick]

Re: C2 1966 Big Block Radiator Identification

Most heating issues can be traced to a few places, unless there is something obviously wrong, like wrong radiator. These cars didn't run hot new, so they shouldn't now.

1. Missing parts. Missing fan shrouds, seals, and such do not let air go through the radiator correctly and so cooling is impaired. Make sure all parts are there and in place.

2. Old radiators. With age, they cool less from deposits, rust, and other build ups inside. The same on the outside, as they are often painted and repainted which puts an insulating layer that helps hold heat in rather than letting it escape. Flush them out, clean them out, and such will restore most cooling, but with age, metal is lost and the cooling is also less. Sometimes, you just need to get a new radiator.

3. Fans, fan clutches, belts, and so on. These often get ignored. In 40 years, these cars got changed around a lot, often with parts that were somewhat the same but not necessarily performance-wise the same. If it heats in traffic, i.e., slow speed or no speed movement, then it sounds like either not enough water or air is being moved. Check that the fan clutch actually works. Hot, it should be tight, and pulling a lot of air. So you have the correct fan on there? Be sure you have the right pulleys. The fan needs to run a certain speed to move enough air and the pump enough water. Belts are commonly replaced with restoration belts, but are they actually gripping or slipping? A slipping belt can let you go up 20 degrees easily. Go buy a good Gates or Dayco replacement and try it to see if it changes. At $6, it is a lot cheaper to try than a $500 radiator.

4. Engine. Water pumps can fail, but it is more likely they leak than simply not flow. High flow aftermarket are entirely unnecessary and often aggravate a problem as they flow too much too fast. Be sure your ignition timing is right. Retarded and you can have it heat up much more than it should. Today's gas often runs hotter than the leaded gas of 40 years ago, so you have less leeway on being correct. Add some detonation and you will be hot quickly. If the engine has been bored out, you may have a problem. I've had friends running .060 over engines that were tea kettles in parades. If that is the case, you have to compensate.

[Joe L.]

Re: C2 1966 Big Block Radiator Identification

Chris----

One correction: many 65-74 Corvette big blocks DID run hot when they were new. It's definitely NOT a problem associated with deterioration of cooling systems, although such problems can make a bad situation worse.

[John H.]

Re: C2 1966 Big Block Radiator Identification

Tom DeWitt's complete restoration radiator is his #BC66M (for '66) and #BC67M (for '67-'68); check out the catalog or website for the details.

[Mark P.]

Re: C2 1966 Big Block Radiator Identification

Thanks gentlemen. The current radiator has been gone through and is clean. Basically, I think it's the best it will ever get. The water pump has not presented any problems, especialy with movement or leaking. I have a new rebuilt original water pump that I'll be replacing it with anyway. The fan shroud is in place and the fan clutch works fine. That's why I'm a little more focused on the radiator than the other components.

Although I would like the additional cooling, I'd still like it to score well in judging when I have it judged. That's the decision that I am faced with now.

Thanks,
Mark