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1969 Nova SS502
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131 Posts
Discussion Starter · #1 ·
I currently have a 19x28 single pass aluminum radiator with a Walker electric fan/shroud in my Nova. This is a fresh motor and seems to run hotter than my 396 did. The 396 ran mostly around 190 and the 502 will run as hot at 205--both with short drives around town. My question-- is a dual pass radiator better at cooling than my single pass radiator? I can modify the radiator area and get a 19x31 in the car but then the shroud will not cover the entire cooling area on the radiator. Any ideas?
 

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http://www.warsprints.com
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2,024 Posts
redride said:
I currently have a 19x28 single pass aluminum radiator with a Walker electric fan/shroud in my Nova. This is a fresh motor and seems to run hotter than my 396 did. The 396 ran mostly around 190 and the 502 will run as hot at 205--both with short drives around town. My question-- is a dual pass radiator better at cooling than my single pass radiator? I can modify the radiator area and get a 19x31 in the car but then the shroud will not cover the entire cooling area on the radiator. Any ideas?
I would change the fan to a belt driven thermo (clutch) fan. That should help alot.
 

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WFO
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5,030 Posts
redride said:
This is a fresh motor and seems to run hotter than my 396 did. The 396 ran mostly around 190 and the 502 will run as hot at 205--both with short drives around town. My question-- is a dual pass radiator better at cooling than my single pass radiator?
A single-pass system- if adequately sized- will do fine.

The water pump's drive ratio is often overlooked when a cooling issue arises. I'd suggest you go to at least a 1:1 W/P to crank drive ratio, to as much as 1.3:1 (W/P overdriven).

This flies in the face of "power saving", "HP freeing" underdrive pulleys that are sold in the aftermarket. While an underdrive set-up CAN reduce the parasitic drag on an engine, it does nothing good AFA cooling the engine goes. If I were to have to choose between an "extra" 5-10 HP or an engine that runs @ 190 degrees as opposed to 220 degrees, I'll take the 190 and eat the HP "loss". This doesn't necessarily even apply to the OP- but is an issue w/a lot of guys looking to do simple, "computer-friendly" modifications to their Mustangs and Camaros.

With the use of electric fans, the HP savings can amount to as much as 25-plus HP over those crappy plastic flex fans. Even a good clutch fan set-up can use up 10 HP pretty easily, so use some of that savings on turning the pump faster, IMO.

The electric fan shrouds typically don't cover the entire surface of the radiator. Most shoot for about 70%-plus, Flex-a-lite says a minimum of 60%. Obviously, more is better as long as the fan is adequate for the app.

Does the engine cool down at highway speeds?
 

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1969 Nova SS502
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131 Posts
Discussion Starter · #8 ·
The shroud covers 100% of the cooling area. I have all the air out and am running 91 fuel. I never drive it at highway speed (geared 4.10) and with my Doug Nash 5 speed, 5th is 1 to 1 so about 60 is about all I will run on the small loop around our town. It does not cool down on this short drive. The water pump I am using is a high flow Weiand action +plus.
 

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Car? Truck? Who Cares
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2,485 Posts
alittle1 said:
Did you get ALL the air out of the system when you installed it??? Back off a little on the timing, somewhere around 34 - 36 deg. Use some 91 octane fuel.
I have a 454HO in the 59 Elky
2 row BeCool, twin 11" Spal fans
set to come on @ 225.

My timing is right at 48* with the vacuum advance and is in @2500. (18*initial)<<<<<I think
I really need to get this to come in quicker as in 5th @70mph only 2100RPM, and all the advance is not there yet.

As a general rule, this car will run right at 180-190 in 100* outside air.

Temps only creep up in turbulent air (behind traffic), or when sitting at an intersection.

So, at 70mph, you are spinning what----3700??
 

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1969 Nova SS502
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131 Posts
Discussion Starter · #10 ·
3000rpm at 65. I live in Texas so right now it is over 100 every day, 102 today, so I only drive the car early or late trying to avoid the heat. I think I am going to buy the bigger rad 20x31 and change the shroud on my fan to fit the cooling area on the new rad. If this does not work????
 

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Car? Truck? Who Cares
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2,485 Posts
I'm in San Antonio
Been a hot mutha last couple of days.

Spent most of today at a friend's body shop working on my 66 Elky
100*+. humidity at about 10,000%, in a metal building :pain:

no end of this in sight either-----
 

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On my 70 Chevelle with LS6, I run around 210. I have a six blade deep pitch mechanical fan spaced out for 1/2" inside factory shroud. I have the rubber fender shields that cover the suspension removed to allow for more air movement. Besides getting air to come in through the rad, I also am concerned with removing 'heated air' from the engine compartment.

My rad is a four core brass, 20 # cap with a puke tank connected in closed circuit to take coolant back in the rad when it cools down. I run a 195 thermostat. I run a 50/50 mixture of distilled water/antifreeze with two bottles of Water Wetter in solution.

While in crawl traffic, I shift to neutral and add rpms to the engine to draw in more air and spin the water pump faster. My torque converter is a Street Fighter with 2800 stall, trans temp runs 245 - 250.

I try to keep my cruising time to the cooler part of the day.
 
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