[amatojm]

Hey all

I'm mocking up my cooling system on the stand before I get my '74 back from paint.

I currently have:
1 x electric fan
1 x mechanical fan
1 x 2" spacer
1 x fan clutch

I do not have a fan for the clutch, or a temp send/relay for the electric fan.

So I have decided to order a fixed blade fan for the clutch and the spacer. It looks like this will place the blade about 1 5/8 from the radiator and about 2/3 into the shroud, maybe a little more.

But it looks like I goofed a year ago when I ordered my Grifiin radiator. The core isn't wide enough to accept the stock fan shroud.
The side lips of the shroud are resting on the tanks of the radiator rather than flat on the core. This is creating an air gap between the shroud and core.
Will this cause the factory tray to not fit correctly?

Also, when in place, is the fan centered in the shroud side to side and up and down? If it is, it looks like I can fit up to an 18" blade.
What side blade came stock with these??

 

[RifRaf]

My 74 Nova came with a 19 1/2" clutch fan from the factory. The shroud opening is 21" diameter.
A replication of the fan I am using can be obtained from Classic Industries (Part #3991431).
1971-1979 All Makes All Models Parts | 3991431 | 1971-79 OER Authorized 19-1/2, 7 Blade Fan | Classic Industries
If you have a fan shroud that has a smaller diameter and it will except an 18" diameter fan, I would recommend looking at the Goodmark GMK 4012312681.
Goodmark Mechanical Cooling Fans GMK4012312681
Your fan spacing with the mechanical clutch fan and spacer looks pretty good.

You can try some adhesive HVAC roll insulation attached between the shroud and the radiator to help fill the gaps between the two.
You may also need to make some modifications... or add some brackets to attach the top portion of the fan shroud to the upper radiator cover (tray).

 

[amatojm]

After posting, I realized it would be really easy to just trim the edges of the shroud if needed to have it sit flush so the cover tray can bolt to the radiator support.

Biggest concern is having the proper diameter fan. I would hate to have to end up playing the cooling game with a new build.

My shroud measures 21" so I should be able to get that 19.5" in no problem, as long as everything is centered.

Will this setup maintain 190-200* temp?

 

[RifRaf]

As long as your radiator is properly sized for your engine's displacement and HP, plus a good water pump... you should be fine for the cooling needs with your set-up.

I have a very healthy 400 sbc with a 31" wide aluminum radiator, high volume water pump, 19 1/2" mechanical fan w/clutch (Hayden HD Clutch part #2747), and a 21" fan shroud. My engine never gets over 180° (180° thermostat) at idle, stop & go, and cruising while the outside temps are 95+ degrees.

 

[amatojm]

Thanks for the photos for reference. I'm willing to bet I will need to get a shorter spacer or chuck it all together.
My radiator isn't as wide as the stock unit so I'm sure the hoses I have (correct part for '74 350) are pushing the radiator further away on the stand than it will be in the car.
I know the radiator is up to the task, with the 16" electric fan mounted and no shroud, I turn it on idling when I feel the upper hose getting warm and the gauge doesn't move after that. I'm sure a 19" mechanical fan with shroud will cool it no problem.

For reference, this is the radiator I have....

Griffin Thermal Products 1-25242-XS Griffin Universal Fit Radiators | Summit Racing

Find Griffin Thermal Products 1-25242-XS Griffin Universal Fit Radiators and get Free Shipping on Orders Over $99 at Summit Racing! Griffin universal fit radiators are constructed of lightweight, high-grade aluminum to ensure flawless performance on and off the track. They are available with...

www.summitracing.com

 

[RifRaf]

I did not use a spacer when I mounted my clutch fan. My fan blades sit aprox half-in and half-out from the shroud.
Your listed Griffin radiator is still a pretty decent sized aluminum radiator... 27" wide (22.5" wide core).

If your upper and lower radiator hoses are just a little too long for the desired radiator position, just cut some length of the upper hose at the end that attaches to the thermostat housing... and cut some length of the lower hose at the end that attaches to the water pump to adjust the spacing as needed.