My 1968 Camaro engine is a Dart 565 c/w Dart Pro1 heads Mild Comp Cam hydraulic roller 605 Hp / 704 ft. lbs. Torq. Turbo 400. Cooling system is a 2 row Becool Alum. Rad. C/W 2 12" Pull Fans with controller. Edelbrock High Performance water pump, 160 Thermo gasket / 16 lb. Rad. Cap. Trans cooler and power steering coolers are seperate. I live in a Desert area of B.C. Canada temperatures in day time range from 85 to 95 degrees F. This month I have started to experience the radiator bubbling over and steam everywhere. So I changed out the thermostat and even drilled a 1/8" hole to allow air to escape. The car has boiled over three times now. I believe I have made a cardinal mistake when it comes to anti Freeze coolants. I figured that all the water was steamed out, after letting the engine go cold, i filled it with One gallon of 100% antifreeze topped up the water, let it run without the rad cap on. Went and drove the car three mile on the highway got home and blew off the heater hose. In doing research I should have used a 50/50 mix which has Distilled water. I am very concerned that I have now a blown ahead gasket or have warped the Alum. Heads. The car doesn't give off white smoke from the exhaust, the spark plugs are burning properly. Engine runs strong no misses, no water on the dip stick, No residue on the underside of the oil cap. I am ready to do a comprssion check which may isolate the engine side and which cylinder. The question I have for you First Generation guys is that by just dumping 100% anti freeze into the raditor and only running the engine for a short period of time be what has caused this steaming issue. If not do I take the car to a raditor shop for their testing. The other question that I need some advice is obiviously I need to go to a cross flow Rad. but also how many rows and tube size, and most importantly which manufacture has a good reputation ( Bad Comments on Griffin Rads. ) Your assistance would be greatly assisted in solving my over heating issue. Kamloops B.C. Canada Bobsbrat 1968 S.S. Camaro Coupe.

 

well to comepare a bit I have sbc gen 1 406 with a 3 core champion radiator ,I pride it as my best deal on an aluminum radiator $220.00 an has worked great ,I have had things like wire to my fans came unhooked couse a small over heat sodered now ,then my alternator bracket was the next now I have it set up right an tight ? it almost seems a 2 core to small for big block ,I hear atleast 3 an 4 cores with those an more ,an yes on my second one, key was to check the radiator after letting it idle mine holds totally 2 gallons of dexcool an it seems one is held in the hoses an internals the other the radiator ,those 2 short ones did no damage to mine with iron heads ,if it runs fine at ldle you should be ok ,just check it more often the anti freeze in summer I check mine every few days,dont think 100% did any harm either some guys sware by it ,just make sure its full an check it every day ,they can tend to use some anti freeze on hot days too,i need to drain mine again an add dexcool as I have water an dexcool in it now as its like not 50/50 from testing ,I would see how much you may be buring off on hot days ,an go from there ,that's a lot hp for a 2 core radiator I am in 420hp range an 475tlbs an mine likes the cooler days unless on highway all the power makes alot of heat I have mr gasket temp sencor with 30 amp fuse turns the fans on 190 an shut them off around 160 an I use hand held heat sencor that tells me 185 an 153 off iwanted to run it cool couse I knew it would run hot , my guage goes to 200 an off at 170,its a great kit ,so its set from 190 on 160 off I also run nothing but dexcool 50/50 orange ,welcome to the forum

 

You don't need to run 50/50. You can straight water if it's summer only (just remember to drain during cold months) or 70/30 coolant/water mix or 30/70 coolant/water mix. 50/50 just gives the best balance between keeping the engine cool and protecting from freezing. Where else, 30/70 (C/W) will give better cooling while 70/30 (C/W) will give better freeze protection.

The reason it says distilled water is because tap water varies in "purity" between place to place. I have no issues using tap water in my cooling system because I know in my area, our water contains less heavy metals and impurities than other places. Never had an issue.

You can try adding Lucas SuperCoolant, RedLine Water Wetter, or Hyper-Lubes Coolant additive. These are supposed to help the cooling system by allowing greater heat transfer from the block/head to the water/coolant mix.

Check to make sure your fans are operating correctly and you could also add a lower temp t-stat that will open at a lower temperature. You may also have air stuck in the system. Air does not transfer heat well. Running pure antifreeze/coolant wouldn't hurt the engine, it just won't give you the best cooling efficiency.

 

i still think 2 core may not be getting it for the big engine though we pretty much told him the same things ,like trying a lower temp sencor,most places that talk about bbc ,a 396 402 all mention a 4 core radiator an with this beast of 565 I also read something about 2 rows are rated for around the 400 500 hp range too an the 3 would be around 1000hp an a 4 more,this was for champion radiators ,without huge price tags but do as well as the $1000.00 ones do

 

You added a gallon of antifreeze, then topped it up with water. Plus, you already had a mix in the engine. You weren't running straight antifreeze, so don't worry about that.
A couple few things:
1. You swapped the thermostat, was the old one a 160 also? Either way, put in a 180 or 192, this will give the coolant more time to spend in the radiator to cool off more. Once the engine is up to running temperature, and if the coolant in the radiator hasn't had sufficient time to cool below the 160 level, then the thermostat will stay open, essentially like running without one. Using a 160 stat isn't a good idea for any year, for that reason, but people mistakenly think a lower temp stat will make the engine run cooler.
2. Have you checked your ignition timing? Too far in either direction can make the engine run too hot.
3. Do you have that neat looking aluminum flat shrouding surrounding the radiator fans? That can actually restrict the air flow through the radiator and cause overheating.

 

ok may be a misunderstanding ?you meen the thermostat ,not the temp sencor ,I know about the 160 thermostat right they don't work an can throw the engine way off an that's what I think did my lt1 in along with burnouts an old seals,an they say there for older cars that run a bit hot but there crap right for sure sorry hectic day ,I was talking about the temp sencor turning the fans on at 190 an off at 160 ,at the advice of the engine builder ,+ I looked up stats on 2 core or 2 row radiators saying most were only good to about 400hp,i think he asked if putting 100% antifreeze in for short time then running it could couse over heating too

 

Radiators are generally designed for a 20°F differential across core.
Thermostats start to open at stamped temp, fully open +10°F later.
Big problem with earlier years is recirculation of hot air.
GM put a length of 2 inch square foam on radiator support sealing against the hood, and put baffles about the headlamp assemblies.
One could add a plate/shield between the bottom of valance panel to bottom of rad support.

 

funny we get so many of these 2 weeks no response ,guess he is all set or busy