ran this thing this weekend for 20 minutes through town and she went over 240 degrees and blew her top, even with a 22-24 # cap. the motor is running rich, blowing black smoke out the exhaust. running 92-93 octane gas. there is no water in the oil. i'm running a a/c water pump, the timing was checked with the vacuum disconnected. thanks for the advice looks like i've got to get into the motor a little deeper. maybe the distributor and vacuum advance also. thanks, duane
Is that 28x19 overall dimensions? What are the core dimesions? Is is a 2-row with 1" tubes (i.e. just over 2" thick)? Be careful of aftermarket electric fans other than Spal or Derale. Testing has proven that many others will inflate the advertised cfm ratings. A good rule of thumb is roughly 100 cfm per continous amp draw. Can you fit a 19.5" seven blade GM fan in your shroud? If so, you might want to try that with the Severe-Duty clutch. Could you fit an aditional pusher fan in front of the rad?
the overall dimensions are 28x19, 2- row just over 2' thick. i'm not running a shroud now as it would not fit the radiator. i can run an additional pusher fan in front but, it would have to be a small one. I'm going to call on having a 5-core radiator made and make up a shroud to fit it. maybe that will help cure the problem. thanks, duane
duane, you absolutely have to run the shroud. I bet that is most of your problem. The aluminum radiators are supposed to be really good at cooling, but at idle you aren't getting the draw from the fans. I'd go back to the old clutch fan with a shroud and ditch the electric fans for now. Also, reman water pumps can have 2 different impellors. The best one will have the blades that go all the way to the end of the impellor. Short blades will not pump as much water and migth contribute to your over heating. Contact simco water pumps and ask for an impellor with full blades for the 455. the number is 313-895-5666. They have helped me in the past. never had a problem since.
thanks for the help. i'll give them a call, pull my water pump and check to see what i have and change the thermostat also. I'm going to have to build a shroud (have access to an aluminum brake). again thanks for the help, duane
I bet you don't have enough water in your motor. I know becuase I had your same problem. You gotta open up the radiator cap when the car is cold and start the car and let it heat way up. All the while adding more and more coolant. It should take like 15 minutes at idle. Then when the water is hot hot, it should start to flow over the radiator hole. Put the cap on and you know have a full system of water. (as full as you can get it) I am running a similar radiator, and When I made the switch, I incorrectly filled the radiator, and what little water it had would quickly dissapate, as I had to keep adding more and more water with no leaks.uzzled: I would also like to add the fact that if you don't have good electric fans. ($100 plus) it will also aid in the over heating. Try this first if you havn't done so. You can see here, I have no shroud, just 2 good puller fans ONLY. This was an 11:1 455 that ran low 12's, I could take it out on an 88 degree day or a 60, and the temp would sit at 180.
when i had the 4-core radiator in i also had a new shroud and it still overheated. I'm running 10" & 14" electric fans. (was) just pulled both fans off and went back to a clutch fan. i've got the largest fan blades i could fit in and still close the hood. i've got good water flow through the radiator(filled system with cap off and topping it off until full). ( i'm still going to build a shroud) the temp climbs when the motor is off now. It was running at idle and stayed around 170 for a while then slowly started to climb. i'm also going to check the water pump vanes for size and add one of the electric fans as a pusher as the clutch fan is slitly off set from center. i'm also going to move the external h.d. trans cooler to a different location instead of in front of the radiator. thanks, duane
I JUST WENT THREW THE OVER HEAT BLUES AFTER I REBUILT MY MOTER AND RAISED COMPRESSION, DID IT ALL, COOLED DOWN GOOD ENOUGH AFTER NEW 4 ROW,BUT IF OVER 95 OUTSIDE FORGET IT, THEN AFTER JUST LOOKING IN TO PUTTING UNDER DRIVE PULLYS ON FOR RACING, FOUND THAT MY CAR HAD THEM ALL ALONG, IT RAN COOL WHEN THE MOTER WAS BONE STOCK, SO I JUST PUT THE SMALLER WATER PUMP PULLY ON AND ITS FIXED!!! WONT GO ABOVE 190 NOW EVEN AT IDLE 95+
..... Did you plug the holes in the block for EGR when you put on the 70 heads? This could cause an overheating condition like your describing since you've already gone through every other part of the cooling system.
It is the head gaskets. I went through the same problem with my 74 block and 71 heads. I would check with TA Performance and they can tell you if you should get the corresponding head gasket to either match the year of the head or the year of the block. I forget which it is, but after switching head gaskets my temps went from 215 to 165 with a stock four row and 160 thermostat.
equiptment The radiator is a northern radiator. It is one of the biggest Al radiators you can buy. However I had to "message" the core support radiator holddown. The fans are from summit. A big 16" and a 12" both run off of seperate toggles becuase you don't always need them on together. I have them set up to both pull. I also have a small one on my trans cooler, that you can't see from the picture. I don't have the part numbers from summit but they cost me about $200 for both the fans, and they come with nice mounting tabs so you don'd ruin your nice shiny radiator. The radiator is from a local shop in town. I paid $215 for the radiator, which is a lot cheaper than some. I can get the number of the shop if others are interested. I plan on using this setup to cool my 625+HP 13:1 motor next spring.
thanks for all the help. right now i'm in the process of making a fiberglass shroud to fully enclose the radiator plus it's 5" deep which encloses the fan. i'm going to move the trans cooler to another location(with a 10" fan) and install a 12" pusher fan of to one side( the clutch fan does'nt cover the whole radiator) and hook it up to a thermostat as the motor temp climbs when the engine is shut off. I'll probably will get into the heads over the winter. again thanks a heep for all the help,duane
thanks for all the help. right now i'm in the process of making a fiberglass shroud to fully enclose the radiator plus it's 5" deep which encloses the fan. i'm going to move the trans cooler to another location(with a 10" fan) and install a 12" pusher fan of to one side( the clutch fan does'nt cover the whole radiator) and hook it up to a thermostat as the motor temp climbs when the engine is shut off. I'll probably will get into the heads over the winter. again thanks a heep for all the help,duane
Temp. Gauge? If the radiator over flowed your gauge is probably accurate. But check it out maybe it reads hotter than it really is.
thanks for all the help. right now i'm in the process of making a fiberglass shroud to fully enclose the radiator plus it's 5" deep which encloses the fan. i'm going to move the trans cooler to another location(with a 10" fan) and install a 12" electric pusher fan off to one side of the radiator as the clutch fan does'nt cover the whole radiator and use a thermostat on the electric to help cool when the motor is shut down. i'll probably will get into the heads this winter. just pulled the water pump and checked the vanes out. they don't come to the edge of the housing(pictures available). i should have the shroud done by next week. again thank a heep for the help, duane
just made a new shroud for the motor, removed the electric fans, checked the water pump, installed the clutch fan, and rechecked the thermostat. with the new shroud(which encloses the entire fin area of the radiator) the temps stay around 170 degrees on the highway and around 180 degrees in town driving. while the outside temps have been in the low 80's so far, i still want to do some more testing with in town driving. i did'nt move the trans cooler yet and probably could use a higher flow water pump if problems arise. the shroud measures 25"x21"x5" and the fan sits inside the shroud completly. i have pictures of the set-up if anyone is interested. again thanks for all the help, duane :grin:
