rongold

Hi all,

I have a 67 435 HP car with an original style copper/brass radiator. As with all 67 435 HP cars, the radiator is too small in capacity, and it runs HOT !!! In fact, if the temp is expected to be over 85 degrees, I won't even take it out.

I'm thinking of replacing the radiator with an aluminum one from DeWitt, as I've heard that they add more capacity and usually reduce the temperature quite a bit. Does anyone here have any experience using an aluminum radiator in a solid lifter big block car (C2) ??? The later models (C3) (68-70) have wider radiators in them and have extra cooling capacity, so they can't be compared. I'm mainly interested in 66 425 HP and 67 435 HP cars for comparison.

One thing that bothers me about an all aluminum radiator is that the neck that the radiator cap installs to is also made of aluminum. I had a car with an aluminum radiator in my shop a number of years ago, and when I removed the radiator cap and reinstalled it, I saw small aluminum shavings fall off of the cap. The cap was actually wearing away the neck. Does anyone here have any experience with that problem ???


RON

Hitch

All I know is that Tom DeWitt has the best replacement radiators anywhere.. He's a forum member and supporting vendor.. Look at the tool bar on the left and you will find his website.. Do a search under overheating, radiator or dewitts and you will find a large amount of satisfied customers.. Dave.

nassau66427

I have been using an aluminum radiator in my BB for 5 years now. It doesn't overheat on 90+ degree days in traffic. I haven't experienced any problems with the cap. The needle on my temp guage doesn't even get within an 8th of an inch of the "straight up" line on the guage.

SWCDuke

The original radiator design is fine, but over the years, they get clogged up with the high salt antifreezes that we used to use (use Zerex G-05 HOAT nowadays). Since your radiator is brass, it can be disassembled and the tubes rodded out. This is much cheaper than buying a different design radiator that you have to bubbaeer to adapt to the car. And retaining the original radiator helps retain the car's value. If it has a brass tag with the number, remove it before you take it to a shop and reinstall it when you get it back. Radiator shops throw them away, even if you ask them not to.

The other issue you have is "ported vacuum advance" - no vacuum advance at idle, which was establilshed to meet CA emissions. Even if your car is a 49-state model, it still has ported vacuum advance. GM chose to built only one version of L-72/71 to meet CA emissions since it was a low volume option. No vacuum advance at idle increases EGT to enable oxidation in the exhaust, but it also throws A LOT of heat into the cooling system as the hotter exhaust travels through the head ports.

To convert to full time vacuum advance, you must route the vacuum can signal line to a full time vacuum source, and teeing into the choke vacuum break line on the center carb. is a good spot.

Also, the installed vacuum can, which doesn't provide full advance until about 15", is not a good choice for full time vacuum advance, since idle vacuum may not be enough to pull it to the limit at idle, so install a NAPA/Echlin VC1765, which provides full vacuum advance at 12".

The cost of a 1/8" tee, a couple of feet of 1/8" vacuum tubing (just remove the original choke vacuum break hose, save it, and make a complete new hose harness with the tee), and a vacuum can shouldn' t be more than about 20 bucks. Do this first, and you may well find that there is nothing "wrong" with your radiator.

With a 12" can powered by a full time vacuum signal, the engine will not run as hot at idle and low speed driving, it will achieve better fuel economy, and will have better throttle response. Once you have installed the VC1765 with full time manifold vacuum signal, you will need to go through the idle speed and mixture adjustment procedure.

Duke

Vette-66

Since my BB (427/425) now has a clean copper/brass I have NOT had any heat problems and it has been driven slow on 95deg days, the temp gauge never hit the vertical line.

The car is in a heated garage for winter, I run a mixture of water, 12% antifreeze, and water wetter.

Chuck

0Tom@Dewitt

It's not too often (never) I disagree with the Duke, but I like the idea of going aluminum with the 66-67-68 bb cars. Personally I think GM made a mistake when they put a 22.5" copper/brass radiator in these cars. As you pointed out, GM switched to a 27.5" copper/brass radiator in C3's and used it all the way up to 1982. That included whimpy smog small blocks! What that tells me is, engineering looked at the cooling system and said "we need a bigger radiator". I posted a fact about the BB 67 (3008567) radiator vs the SB 67 (3155316) a few years ago. The short version of this was that the sb radiator had more cooling btu rating than the bb. Most people get fooled thinking the bb copper is a "bigger" radiator only because of the measurements. The core is the only part that does anything and it's the same size as the small block 22.5" wide.
I make a "correct" copper/brass 4-row for guys that what to re-core and keep the original look and I sell a complete repro but often people call me after installing one and tell me they still run a little on the hot side. That never happens when I sell an aluminum one. Our aluminum version (A66M) uses the stock type "hat" channels with the cut outs and press formed tanks. To the un-trained eye, they might slip by as the real thing when painted. (and no that doesn't affect cooling). I have a motto about sacrificing your driving enjoyment for 5-10 more show points. It goes like this "Install the aluminum one and enjoy your car the other 364 days of the year" To stare at the gauge all the time and limit the days you can drive, just to remain stock doesn't make any since to me at all.

Of course do all the standard trouble shooting techniques first and make sure everything is up to snuff before investing into a new radiator of any kind. IMO

wombvette

I agree that more cooling is better, but I disagree that a stock original radiator in a 66-67 BB is not capable of cooling the engine. The problems experienced are a result of reduced efficiency. Factors include reduced flow, bad shroud fits and seals, and most importantly the fins coming loose from the tubes. Any or all of these things result in problems. A good new or newly cored original radiator will cool just fine. I have never had a problem with my 390- AC convertible even on the hottest days with the AC on.

TJefferson2020

Don't know much about the BB's but I do know that my built 1970 LT1 in my C2 runs about 200 degrees cooler on a 100 degree day with my new DeWitts aluminum replacement radiator. It has less cooling capacity than the repro version but still never gets above 160!

Thanks, Tom!!!

revupL78

Dewitts keeps my 396 car running cool

wombvette

Better watch that thing pj, 200 degrees cooler, it might freeze up on ya.

MidYearRoadster

I Recently Installed Dewitts Aluminum Radiator In My Big Block C2...although The Stock Radiator Did A Good Job And I Never Overheated...i Said What The He.l It Went Right In..fit Perfectly...had It Painted At Dewitts.....you Cant Tell The Difference... Anyway...its Been Hot As Heck Here With High Humidity...i Have Had The Car Zinging On The Highway At A Constant 3500 Rpm For Miles And Miles....and I Have Been Stuck In Traffic...barely Moving An Inch....this Radiator Works People.....now I Dont Know If My Guage Was Off Or Not But My Car Would Normally Be Hugging 210 On Hot Days...never Going Over. With The Dewitts If It Makes It Half Way Between The First Line And The 210 Line ..its Something...all I Know Is That If The Car Is Running Cooler The Motor Must Like It As Much As I Do......

66BBCoupe

Running my re-cored original copper/brass radiator - stock 427/425 runs a cool 200 degrees even on the hottest of days - never a problem. You have to view your cooling system as an integrated one with the entire engine. Radiator, water pump, shroud, fan, fan clutch, hoses, block condition, tuning all must be in top condition and proper form. If so - no problemo.

rgs

It's an interesting point that the first big blocks, the 65 396's, and the 20 '67 L88 came with aluminum radiators originally.

Rongold ... all of the expansion tanks are aluminum in the C2s that use them. That is where the radiator cap resides on those. I wouldn't worry about the cap on an aluminum radiator. We've used aluminum radiators in race cars for years with no issues there.

BTW .. just got my new Dewitt yesterday also. looks great.

67-427ci

with Tom DeWitt and SWCDuke:
Been there and done that with my '67 Big Block car. Between the DeWitt radiator and setting the timing properly, I have -0- temperature problems. I drove my car just over 1,000 miles last week. One day I made four 80 mile trips in 95* weather which included 1 hour in stop and go traffic in Rochester, NY. Even though it was hot in my car, the engine NEVER rose above 190*.
Roy