I bought this car 3 years ago with a March pulley setup with two 4 groove belts, one running the water pump and alternator and the other running the power steering pump. The PO had removed the fan and clutch and added a Hayden 14" electric fan in the middle of the radiator. This setup used to work ok in the heat, but since I swapped heads with bigger valves and a new cam I am getting really hot in the higher temps above 85. If I am sitting in traffic in heat over 85+ I will reach 230+ quickly. I have resorted to running the heater at high to keep it below 210.. This was not the case before the head / cam swap. I have good clean coolant in the radiator and overflow and the cooling system seems to be working as it should. The only new item in the cooling mix is a new thermostat since the old one was sticking. I replaced it with a 190* thermo from Napa. I know it can't be the thermo, unless it is flowing less coolant. But that does not seem like it would be the issue.
Currently the electric fan only covers a 14" diameter space on the radiator. The radiator looks original so I could go with a DeWitt and electric fans, but I would like to hear what other have done.
This is a kinda non stock 350 ( Stock short block L48 with 1094 Felrpo Head gaskets) with Edelbrock intake and 1406 carb and an MSD Dual spark ignition/6AL CDI and an under the hood Triangle Edelbrok intake.. so it is getting hot air from under the hood. Nothing too big to cool efficiently and run low octane gas. Engine runs excellent and never doesn't start on the first click.
I am thinking of either removing the thermostat in the summer.
Or replacing the radiator with an aftermarket DeWitt or similar
or replacing the 14" hayden fan with a dual 13" that has a small shroud that covers the entire radiator.
Just looking for opinions and facts.. Usually get great advice here.
Daytona Yellow '75 350 Muncie 4 spd
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Pat, check your ignition timing....you may need a wee bit more advance. Retarded iggy timing will make the engine run hotter than it should. How confident are in in your temp gauge? Most electric gauges aren't all that accurate. 230*+ temps should have that thing puking the coolant out once you turn the engine off. If you can, try comparing the gauge temp to actual engine temp with an infrared temp gun....see if the engine is actually getting that hot.
Running with no t-stat at all will work as a test, but it's not good for continued driving. The t-stat does more than try to regulate coolant temps...it also regulates coolant flow thru the raditator. If the coolant flows thru the rad too fast, it won't have time to actually transfer coolant heat to the air. No t-stat can also cause leaks and possibly breaks/cracks in the rad, with the coolant gushing right out of the engine into the hose with no restriction at all. If you don't want to run with a t-sat all summer, then get your old t-stat, and cut the center tower part(with the "pill") out, and then reinstall just the outer part, to use as a restrictor.
Of course, all of this is assuming the rad is clean inside and out, and the seals for the shroud are in place. Also, since you mentioned the aftermarket pulleys, do you know if they slow down the water pump speed? That could be an issue, too.
____________________________________ Joel Adams C3VR Lifetime Member #56 My Link
Thanks to all for the info. I am going to revisit the timing in a few, it was at 36* at 3k rpm when I finished the cam/heads install. I am also thinking of adding a bottle of water wetter since it looks like a no brainer at $12.00.. The radiator looks stock and was working fine in last summers heat and traffic, but not exactly sure of its condition. The last thing I want to do is open the cooling system to swap t-stats. Wasn't really wanting to run without one, but if I have to visit the t-stat I would likely buy a new high flow 180*. I'm not sure if the March pulleys are underdriven but if someone has the diameter of the stock crank pulley and water pump pulley I could figure it out..
As for the shroud.. It never had one when I got the car but the PO offered it to me but it was cracked in two pieces so I did not take it. But it's been a few years and the only time it went above 210 was when the coolant was low. Never thought I would need a shroud since the electric fan is mounted directly to the radiator and not on the motor where it would likely count on the shroud to draft air through the radiator. I have also seen several older 60's and 70's cars at shows without a shroud when using electric fans.. And yes the fan runs when the engine comes up to temps.
I have a IR thermo that I will use later today as the stock water temp gauge is factory and only has three numbers 100, 200 and 280.. I mentioned 230* because it did puke a small amount of coolant out when shut off but nothing major
I added 3* of advance and water wetter and im going to take it out later in the 90+ temps we have and see what she does.. This weekend I am going to make an aluminum fan shroud for this Hayden 14 inch fan so that it is sitting about 3/4 inch off the radiator and will allow more of the radiator to draft air while sitting in traffic. At speeds its not an issue. I already made a cardboard cutout to make sure it will fit and I have a 20" finger brake to get the bends nice and neat. Shouldn't take too long, maybe half a day's work. I am thinking that should make all the difference in the world. Just wondering why this is showing up now and not when I first got this car.
Thanks again to all for the help..
|UPDATED|6/7/2016 4:40:46 PM (AZT)|/UPDATED|
Daytona Yellow '75 350 Muncie 4 spd
Vette(s): 1969 convertible 427/390 5 speed
triple black with L-88 hood;
2013 Grand Sport Coupe, manual, Night Race Blue
The electric fan cannot do its job without a shroud. You need to direct the air through the radiator for it to work properly.
I installed a Dewitt aluminum radiator and dual fans on my '69 427. The fans have a full shroud. The fans turn on at 185 degrees. The water temp never exceeds 200. Since you are not concerned about originality, electric fan(s) with a full shroud are the way to go.
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