I Think I Found My Fan - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**truckster** · 08-05-2020, 11:57 PM

I'm putting a 5.7 L31 Vortec in my 72, complete with the serpentine drive setup. I've been trying to figure out what to do about a fan, since the fan on the Vortec is 19.5 inches and my fan shroud opening is slightly over 19 inches. I considered an electric fan - member 71Rat posted a really nice conversion using a Jeep fan a while back. I really wanted to stay with the clutch fan for now, and I think I finally found the solution. I noticed in the wrecking yard yesterday that the 4.3 S10 has an 11-blade plastic fan, and it measures at 18.25 inches. Hopefully it will work well - I'll keep you posted with what I learn once I get it on the road.

**kwmech** · 08-06-2020, 01:15 AM

If you can get some big block engine stands. Use those, they will move the engine back about 1.5'' which will be enough for the long water pump and a factory clutch fan (reverse rotation) with the big block shroud. Works out perfect. BUT the trans will move back the same amount along with the driveshaft being shortened. The big block stands will also allow you to use the later model "LOG" style manifolds

**truckster** · 08-06-2020, 08:54 AM

Quote:

Originally Posted by kwmech

If you can get some big block engine stands. Use those, they will move the engine back about 1.5'' which will be enough for the long water pump and a factory clutch fan (reverse rotation) with the big block shroud. Works out perfect. BUT the trans will move back the same amount along with the driveshaft being shortened. The big block stands will also allow you to use the later model "LOG" style manifolds

It's in a 4WD K5, so I don't think I'd have any room to move the engine back. The HEI barely clears the firewall. I've measured and distance from the fan doesn't look like a problem.

Thanks for the response.

gmc684x4 · 08-06-2020, 06:04 PM

In a k series the engine is tight to the firewall this is for front diff clearance

Have you checked out a fan from 88 95 ?

The vortec 5.7 96 -02 depending which vehicle it comes from
The fan screws on to a threaded hub on the water pump

You may also have to change pumps too

**truckster** · 08-06-2020, 08:55 PM

I have a new water pump on it and the fan clutch with the 19.5 inch fan. The fan won't fit in my fan shroud.

08-05-2020, 11:57 PM	#1
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 8,031	I Think I Found My Fan I'm putting a 5.7 L31 Vortec in my 72, complete with the serpentine drive setup. I've been trying to figure out what to do about a fan, since the fan on the Vortec is 19.5 inches and my fan shroud opening is slightly over 19 inches. I considered an electric fan - member 71Rat posted a really nice conversion using a Jeep fan a while back. I really wanted to stay with the clutch fan for now, and I think I finally found the solution. I noticed in the wrecking yard yesterday that the 4.3 S10 has an 11-blade plastic fan, and it measures at 18.25 inches. Hopefully it will work well - I'll keep you posted with what I learn once I get it on the road. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

08-06-2020, 01:15 AM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,732	Re: I Think I Found My Fan If you can get some big block engine stands. Use those, they will move the engine back about 1.5'' which will be enough for the long water pump and a factory clutch fan (reverse rotation) with the big block shroud. Works out perfect. BUT the trans will move back the same amount along with the driveshaft being shortened. The big block stands will also allow you to use the later model "LOG" style manifolds

08-06-2020, 06:04 PM	#4
gmc684x4 Registered User Join Date: Jul 2012 Location: Whitehorse yukon Posts: 1,218	Re: I Think I Found My Fan In a k series the engine is tight to the firewall this is for front diff clearance Have you checked out a fan from 88 95 ? The vortec 5.7 96 -02 depending which vehicle it comes from The fan screws on to a threaded hub on the water pump You may also have to change pumps too

08-06-2020, 08:55 PM	#5
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 8,031	Re: I Think I Found My Fan I have a new water pump on it and the fan clutch with the 19.5 inch fan. The fan won't fit in my fan shroud. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson



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