C2 SB DeWitt Radiator.

[Rich G.]

I just installed one in my 1966 L79. Everything he claims is true and then some!
I got this car last september and it has always run in the 210-240 range and I've done alot of things to verify that, but the real tip off was that the temp would steadily climb on the highway and turning the heater on brought it down some. The old radiator (copper/brass) couldn't exchange enough BTU's. It probably was cruddy inside, but the previous owner said he had it checked...who knows. Now it runs at 180 all the time. Anyway, since this forum is for asking questions, here's mine: Why didn't I do this sooner?

Rich Giannotti

[Joe L.]

Re: C2 SB DeWitt Radiator.

Rich------

I don't know why. I've been telling folks this for years. Every time I see a 63-72 small block which originally had an aluminum radiator with a replacement copper/brass, I cringe.

[Duke W.]

Re: C2 SB DeWitt Radiator.

You can take radtiators to a radiator shop for a "flow test" and often they will say they're okay, but "flow tests" are not very scientific or conclusive.

Over time deposits form in the tubes, which increase the thermal resistance of the tube, but still allow plenty of flow. Since the 316 radiators aren't reparable, you might want to saw it in half or in sections to see what the interior of the tubes looks like.

If you want to keep that new DeWitts radiator from building up deposits in the future you would be wise to use an anti-freeze with an organic inhibitor package such as Dexcool. Most of the deposits that build up in the radiator are from the silicates and other inorganic salts that make up the corrosion inhibitors in conventional "green" anti-freeze. These salts, and in particular the silicates are effective at preventing corrosion, but the deposits they leave behind eventually kill radiators as dead as corrosion will kill them.

Dexcool provides both superior corrosion protection to aluminum and doesn't leave behind precipitates in the radiator tubes and other cooling system surfaces. For best protection you should change the anti-freeze every two years regardless of mileage - even if the car is stored. The clock runs on anti-freeze whether the engine is running or not.

Duke

[Duke W.]

Re: C2 SB DeWitt Radiator.

Realize after I wrote my response that the radiator you replaced was a brass clone. If it has soldered-on side tanks they can be removed for a tube inspection and if they're clogged, they can be rodded out. These brass clones don't have the heat transfer capacity of the Harrison aluminm design, but they will work in normal weather for a few years until the tubes start to see some deposit buildup.

You can probably sell it as is to someone who needs a cheap radiator, or spend the $50-100 to get it rebuilt and sell it or keep it as an spare.

Duke

[Rich G.]

Re: C2 SB DeWitt Radiator.

Duke..

Thanks for the useful info..

Rich Giannotti

[Tom Merkel]

Re: C2 SB DeWitt Radiator.

Rich - Been there and done that re: my '67 L-79, and its over-heating problem. Perplexed me no end, until someone along this net offered the same solution: get an AL rad from DeWitts, and chuck the existing copper core.

By the way, why did I even have a copper core in it in the first place? 'Cause I needed a radiator, and naivety on my part said just go get a copper replacement, drop it in, and everything will be OK in my Corvette world. Uh...not so. That's my lesson-learned.

Anyway, I installed a DeWitts last Aug., and everything you related is absolutely true. Took my running temp from 210+ down to where it should be: 180 degs, all the time. No more hassles.

Tom

[Jim T.]

Re: C2 SB DeWitt Radiator.

Joe you would cringe if you saw my original owner 68 for sure. Original aluminum radiator was replaced with a brass/copper radiator shop replacement when I was told the original aluminum radiator could not be repaired for leaks. Cost was the factor with going with the brass/copper. This was in 1973. I am still using the brass/copper replacement and have not had any heating problems in 20 years with the brass/copper replacement.

[Jim T.]

Re: C2 SB DeWitt Radiator.

Make that 30 years from 1973-2003.

[Joe L.]

Re: C2 SB DeWitt Radiator.

Jim------

You've been, indeed, fortunate.

[John Lokay]

Re: C2 SB DeWitt Radiator.

Duke, I have two questions:
1) To change from the standard green-type antifreeze to Dexcool, do I simply backflush the cooling system and then refill with Dexcool?
2) The radiator on my L-72 needs to be replaced and I was thinking about purchasing the now available big-block brass radiator core from DeWitt's and using it with the original end tanks. Is this the way to go or should I think about converting to an aluminum radiator? Thanks

[Duke W.]

Re: C2 SB DeWitt Radiator.

To convert to Dexcool it is best to thoroughly flush the system to remove all traces of the "green" antifreeze. To accomplish this I would recommend removing the heater inlet hose from the inlet manifold system and cold backflushing the system with a garden hose while the block and radiator drain plugs are open. Also flush out the radiator circuit. Once the effluent is colorless and tasteless I think it's also a good idea to do a hot flush - fill the cooling system with water, start the engine and bring it to operating temperature for about five minutes; then drain and check that the effluent is colorless and tasteless. If so, the system should be flushed. If not, do some more cold flushing and another hot flush.

If you still have your original brass radiator, it can be rebuilt. Last year after searching in vain for a "correct" core for my Cosworth Vega brass radiator I consulted with a radiator shop I was referred to by another CV owner. The core was showing evidence of seepage at the tube/end plate interface. Freddies Radiator Service, Artesia, CA told me that they could remove both the tanks and end plates, then rod the core and if the tubes didn't have any holes, they resolder the end plates to the tubes and the tanks to the endplate. I went ahead and had them do the work, the tubes were okay, and I was quite satisfied with the outcome. I still have my original core and the service only cost $75!!! A Corvette radiator would be more expensive because it is bigger.

If you can't find a shop to do this service or would prefer a new core I would definitely go with the DeWitts core as it is likely to be most correct in terms of both appearance and heat transfer capacity. I wouldn't recommend an aluminum radiator in the interest of both maintaining originality and because the OEM brass radiator or a correct replacement should have sufficient cooling capacity, and it should be much more than adequate for a L-72 if you convert from the ported to full vacuum advance.

Duke

[Joe L.]

Re: C2 SB DeWitt Radiator.

John-----

You cannot have an aluminum core installed using your original Harrison end-tanks. The brass end tanks cannot be attached to an aluminum core. Even if they could, I don't think that any core is made which would be compatible with the configuration of the tanks. There are only 2 ways that I know of for you to convert to an aluminum radiator:

1) Install an aluminum aftermarket replacement for your original GM #3008567 copper brass radiator. In my opinion, the best one is the unit manufactured by Griffin. It is sold by DeWitts, too. It will be a direct bolt-in installation. Painted black, the radiator's configuration and appearance will be somewhat similar to the original but it's NOT going to fool even a novice judge (I hope, anyway). This unit will perform and cool better than your original copper-brass, though, but it won't be dramatically different;

2) Install the 65 L-78 set-up. This will mean acquiring a reproduction GM #3007436 wide-core aluminum radiator from DeWitts. You'll have to also obtain the 65 radiator support, 65 fan shroud, and 65 2nd design radiator hoses. Then, since your car doesn't use an external supply tank and the 65 L-78 radiator requires one, you'll have to add the tank, bracket, straps, and hose to your right side inner fender well. This will all be expensive, to say the least. When you're done, it will look very "stock", but it'll be stock for a 65, not a 66. Once again, even a novice judge should be able to discern the swap (again, I hope). Of course, your car could always become one of the "rare 1966 L-72's that got the 65 L-78 radiator set-up".