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Discussion Starter #1
I'm in the process of getting my new zz502 running and ran into another snag. I went with a March pulley setup that comes with a long water pump. The spacing from the front of the water pump pulley to the radiator is only about 3" now. And the Flex fan I have needs about 2-3/4" to clear the alternator and power steering pump. If i remove the spacer it will give me about 1-3/4" which should work, but may still not give enough room for the shroud. Also i will need to cut a portion of the inner fender/radiator supports to have the stock radiator bolt up to the front of the grill with no spacer and even then may need some cuts and tweaks which I didn't want to hack the body apart.

Any thoughts or experience with this? Also in the end I'm sure this stock radiator will need to be replaced to support the heat of the 502 vs the old 327, just not in the plan and budget this summer....if the car sees the street.
 

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In an older car I would have retained the short water pump, that the Deluxe Kit ships with (assumes you bought the Deluxe Kit that is complete from carb to the over sized truck oil pan). It yields more room between the fan and the radiator.

I also feel the flex fan will create issues besides the fitment issue with the alternator pulley. Flex fans do not save energy over a fixed bladed fan despite claims by the retailers. It takes energy to straighten out the flexible blades which deform as well as bend. When they deform they no longer form an air foil to move air and the bending creates shear forces that will cut through aluminum rivets.

GM tried out Hayes flex fans back in the nineties and then recalled every vehicle that had one installed and replaced them with a non-thermostatic fan clutch and a new Hayes Fixed pitch six bladed fan. I pulled out of the dumpster ten at a time and resold them later on at flea markets, but that is another story. GM replaced these fans because they shed blades at high RPM, and newer EFI powered engines where picking up in horsepower as emissions fell creating a renewal of interest in hot rodding.

Here is a picture of a flex fan that had been installed on a 406 SBC in a 1978 Nova belonging to a former Chevrolet line tech who used to replace those flex fans and might have kept one for himself.





All fans have a set RPM limit. Flex-o-Lite determined through testing that most fans were at risk of failing above 5,600 RPM. Even if they didn't throw blades like a deranged Ninja they would go into cavitation which prevents movement of air and creates a lot of noise (big semi's cavitate their fans at the top of every gear, which is why the roar of the fan exceeds the noise of the engine at a stop light drag race. If you use a fan clutch you limit the peak RPM of the fan blade at about 4800 RPM. If you run a thermostatically controlled fan clutch you save 80% of the energy to drive the fan as it free wheels at cruise and when cold.

As to your radiator the original 425 horse 409 A/C equipped radiator should keep your 502 cool with a fan clutch and a seven blade BBC fan. Though an aluminum radiator can be custom built to your heat load and car restrictions as to size requirements.

Big Dave
 

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Discussion Starter #3
The 502 i bought was not complete and the March kit i went with has the long water pump. Maybe I will see what other fan options are out there, but I don't think it will change the spacing other than going with an electric setup. I have the Holley Dominator ECU so i can control the fan speed with that, but it was going to be another fix later down the road.

Will a 409 radiator even fit on the 1967 mounts?
 

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The 502 i bought was not complete and the March kit i went with has the long water pump. Maybe I will see what other fan options are out there, but I don't think it will change the spacing other than going with an electric setup. I have the Holley Dominator ECU so i can control the fan speed with that, but it was going to be another fix later down the road.

Will a 409 radiator even fit on the 1967 mounts?
Sorry I thought you had an earlier X-frame car.

Good news is that the 454 was offered as an option starting in 1970, so there exists a factory four row (BBC and A/C option) extra wide core (BBC heavy duty cooling option) radiator with the closely spaced fins (higher fin count) of an automatic transmission radiator that fits your body style (1965-'70).

You want an automatic transmission radiator because in addition to the heat exchanger in the tank to cool the red hot tranny oil it has the fins placed closer together to generate more surface area.

Big Dave
 

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Will the copper/brass HD radiator work any better than an aluminum one?
Yes and No!

Copper conducts heat better than aluminum does (it also conducts electricity better as well, which is why it is used in hose hold wiring). However aluminum is a stronger metal than copper, which is why high tension cables on the top of the power pole are made of aluminum because they can be stretched tighter to keep those wires from sagging down between the poles.

So a copper brass radiator will actually conduct heat better (sort of) but it is heavier, and much more expensive (they took copper out of pennies decades ago because a penny was worth four cents for the just the copper content).

An aluminum radiator is stronger, lighter, and cheaper (if buying a brand new one) and it will cool better than a copper radiator if it is big enough. Aluminum conducts heat a lot better than cast iron and many other metals, and because it is all aluminum (no stamped brass parts soldered to three eighth inch copper tubing because you can not easily weld two different metals together) it can withstand more pressure than a copper brass radiator.

With stamped tanks and the core painted black an aluminum radiator looks like a copper brass radiator but with two large tubes flattened out to be four times thicker than a copper tube radiator so a two tube all aluminum radiator actually cools better than a four tube copper brass tube radiator.

Big Dave
 

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Discussion Starter #7
I removed the spacer and had to trim the old radiator a little at the bottom to make it fit. The only problem now with the long water pump is spacing for the fan/pulley and the big thing is the shroud. For the fan not to hit the shroud it needs a longer spacer off the pump this is Ok but doesn't that defeat the purpose of the shroud if the fan is recessed in too far? If I have to buy a new fan, clutch, spacer and hope it fits and then find this old radiator still won't cool the BBC I should have just bought a new electric fan setup and been done with it. let me know your thoughts and I could trim some of the shroud, but I hate cutting up another 100 some $ part.
 

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Came across a HotRod dyno shop with Frieberg from Hot Rod magazine as the host. He was testing fans and the factory fluid coupled fan used the least while the large plastic flex fan used the most your light weight aluminum fan was in the middle but it still sucked up 6.3 more horsepower than the clutch fan.

Engine Masters TV with Dave Frieberg

Cooling Fan Shoot-Out! - Engine Masters Ep. 20


Big Dave
 

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You have the wrong fan shroud. The one you have is for a small-block w/HD cooling. You need a big-block fan shroud. The BB shroud is quite a bit thinner than a SB shroud.
 

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Discussion Starter #11
Thanks for the info on the shroud.

I have watched the Engine Master clip and love the show. Too bad they did not look at engine temps and how much CFM's each setup moves. It doesn't do much good to save a few HP if you engine overheats.

I may just get a DeWitts setup with the dual fans and not **** with the old parts too.
 

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In 1966 they used a short water pump, so the long water pump will push the fan closer to the radiator than the fan shroud was designed for. The blades should be half in and half out of the edge of the shroud to maximized air flow.

A fan shroud keeps air from sliding off the end of the blade maximizing the surface area.

You use an anemometer (looks like a ducted fan on a stick) to measure air velocity and a pitot tube with a manometer to measure pressure differentials. I though that they had that equipment in place to compare fan efficiency, but that might have been a different test.

Big Dave
 

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Discussion Starter #15
You use an anemometer (looks like a ducted fan on a stick) to measure air velocity and a pitot tube with a manometer to measure pressure differentials. I though that they had that equipment in place to compare fan efficiency, but that might have been a different test.

Big Dave
It must have been in a different episode, they did place a radiator and shroud like a stock setup would be but did not take any measurement other than HP.
 
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