Fan shroud info clarification - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tomatocity · 07-11-2005, 05:43 PM

Here is information I recieved from ECE Technical Support. Does this mean that the distance between the radiator and motor is an inch less or the fan shroud is an inch closer to the motor?

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Tim, the only difference between the two shrouds is the A/C model is about an inch shorter between the radiaitor and motor.

----- Original Message -----
From: Tim Olmstead
To: techquestions@earlyclassic.com
Sent: Wednesday, July 06, 2005 11:48 PM
Subject: Technical Question

Hello ECE Tech,
I need to purchase a fan shroud for my 1970 C10 2WD 350 w/AC. I noticed you have two a different fan shrouds, one for w/AC (11-3901443) and one for w/o AC (3889079). What is the difference in the fan shrouds?
Tim Olmstead

Longhorn Man · 07-11-2005, 06:18 PM

IIRC, A/C trucks came with a fan clutch, which would move the fan forward....an inch or so. This would make the space from the fan to the rad smaller, and the shroud needs to be an inch shorter too. You want your fan blades to be 1/2 in and 1/2 out of the shroud for max cooling.

tomatocity · 07-11-2005, 06:43 PM

Quote:

Originally Posted by Longhorn Man

IIRC, A/C trucks came with a fan clutch, which would move the fan forward....an inch or so. This would make the space from the fan to the rad smaller, and the shroud needs to be an inch shorter too. You want your fan blades to be 1/2 in and 1/2 out of the shroud for max cooling.

I thought the same about the length and clutch but have you looked at the non-clutch spacer? It has to be 3" long and the bolting points on the clutch fan are probably 2". Tonight I will measure the three clutches I have but I don't have a fixed spacer. I will also measure the radiator to motor depth of the fan shroud.
Longhorn Man I am not disagreeing with you since I don't have any hard facts but it would be nice to have this information for others in the future. I can make things work but I would rather understand why and how they work.

Longhorn Man · 07-11-2005, 07:32 PM

Like I said...IIRC....I am commonly wrong on details.

tomatocity · 07-11-2005, 07:37 PM

Quote:

Originally Posted by Longhorn Man

Like I said...IIRC....I am commonly wrong on details.

this is one acronym I never seem to remember.

LUV2XCLR8 · 07-11-2005, 07:40 PM

Quote:

Originally Posted by tomatocity

this is one acronym I never seem to remember.

If
I
Re
Call

Longhorn Man · 07-11-2005, 07:41 PM

lol...OK
If I Remember Correctly

IIRR
If I Remember Right

tomatocity · 07-11-2005, 10:18 PM

Quote:

Originally Posted by Longhorn Man

IIRC, A/C trucks came with a fan clutch, which would move the fan forward....an inch or so. This would make the space from the fan to the rad smaller, and the shroud needs to be an inch shorter too. You want your fan blades to be 1/2 in and 1/2 out of the shroud for max cooling.

--------------------------------------------------------------------------------------

Final answer from ECE Tech. And the answer does not concern the fan or clutch, sort of.

***No, exactly the opposite. The A/C shroud is shorter, leaving more room for
compressor/crank pullies, belts etc.***

----- Original Message -----
From: "Tim Olmstead" <tim@cwo.com>
To: "Tech Questions" <techquestions@earlyclassic.com>
Sent: Monday, July 11, 2005 2:51 PM
Subject: Re: Technical Question

ECE Tech, does this mean the A/C fan shroud is an inch closer to the motor? What is the reason for the difference in the depth of the fan shrouds. Does it have to do with fixed or clutch fans? Thanks for your time and effort.

Tim Olmstead
Very Hot Sacramento

Longhorn Man · 07-11-2005, 10:20 PM

if the fan sticks out a foot from the engine, what does it matter if there is another belt and a compressor mounted up over a valve cover?

tomatocity · 07-12-2005, 02:20 AM

Quote:

Originally Posted by Longhorn Man

if the fan sticks out a foot from the engine, what does it matter if there is another belt and a compressor mounted up over a valve cover?

...just the messenger! Maybe the non-AC trucks did not come with the fan half in and half out. Gotta find some engine pics of quality restorations. Who is the Canadian guy on Speed that does the killer restorations and a car show? He should know.

**StingRay** · 07-12-2005, 09:57 AM

The show is dream car garage.

badpeanut · 07-12-2005, 01:27 PM

My theory is that AC trucks had 4-row radiators which are bigger hence requiring a shorter shroud.

tomatocity · 07-12-2005, 03:49 PM

Quote:

Originally Posted by badpeanut

My theory is that AC trucks had 4-row radiators which are bigger hence requiring a shorter shroud.

Darn another excellent answer. Are there different upper radiator mounting brackets for a 4-row vs smaller radiator? Tonight I will measure the depth of the shroud I have starting from the upper mounting points to the edge of the fan opening. Can some of you do the same and post your finding? This information should help other member in the future.

Next question is what is the differnece of the installed length of a fixed and clutch fan?

matthufham · 07-12-2005, 05:52 PM

don't ac trucks have a long water pump, and non ac trucks have a short water pump, hence the 1 inch difference. that's how the p/o of my truck explained his home made alternator bracket.

**Stocker** · 07-12-2005, 06:07 PM

Quote:

Originally Posted by badpeanut

My theory is that AC trucks had 4-row radiators which are bigger hence requiring a shorter shroud.

My A/C truck had its original 3-row radiator until last fall....

**Stocker** · 07-12-2005, 06:16 PM

Quote:

Originally Posted by tomatocity

Tonight I will measure the depth of the shroud I have starting from the upper mounting points to the edge of the fan opening. Can some of you do the same and post your finding?

Not sure exactly what you mean... I measured mine from front top center of the shroud (at the lip, next to the top center of the radiator) straight back to the opening for the fan. Nine inches.

tomatocity · 07-12-2005, 10:22 PM

Quote:

Originally Posted by Stocker

Not sure exactly what you mean... I measured mine from front top center of the shroud (at the lip, next to the top center of the radiator) straight back to the opening for the fan. Nine inches.

The only easily accessable common mounting point I could think of was the upper radiator bracket (see pic). As you can see from the common mounting point to the opening edge is approximately 4.5" (see pics). If ECE is correct there should be a fan shroud that is either 3.5" or 5.5" measured from the same points. You can take this measurement without removing anything. Thanks for everyones help.

Longhorn Man · 07-12-2005, 10:58 PM

Quote:

Originally Posted by matthufham

don't ac trucks have a long water pump, and non ac trucks have a short water pump, hence the 1 inch difference. that's how the p/o of my truck explained his home made alternator bracket.

Trucks didn't see long water pumps untill 73, regardless of engine, a/c option, or anything else. Cars got the long pump in 69, with the exception of the corevette which chainged even later than the trucks.
tomatocity, i wasn't directing that at you....just in general...I know you were just relaying the info..my fault, I need to reword my thoughts sometimes.

tomatocity · 07-13-2005, 12:27 AM

tomatocity, i wasn't directing that at you....just in general...I know you were just relaying the info..my fault, I need to reword my thoughts sometimes.[/QUOTE]

Hey no offense taken. Glad to share whatever input we have. Better than talking to ourselves (man that would be a boring conversation for me).

tomatocity · 07-13-2005, 12:28 AM

Quote:

Originally Posted by StingRay

The show is dream car garage.

Thanks StingRay.

**Stocker** · 07-13-2005, 02:27 PM

Quote:

Originally Posted by tomatocity

The only easily accessable common mounting point I could think of was the upper radiator bracket (see pic). As you can see from the common mounting point to the opening edge is approximately 4.5" (see pics). If ECE is correct there should be a fan shroud that is either 3.5" or 5.5" measured from the same points. You can take this measurement without removing anything. Thanks for everyones help.

This measurement on mine is 7 3/4".

tomatocity · 07-14-2005, 02:34 AM

Quote:

Originally Posted by Stocker

This measurement on mine is 7 3/4".

This is on your K20 SBC? Now there is another question. Do 4x4 and 2WD use the same shrouds? Hmmmmmmm!

**Stocker** · 07-14-2005, 10:23 AM

Tomatocity, I should add that my shroud does not look like the one in your pics. I don't have a digital camera, but I'll try to describe it. Rather than the sudden transition a couple inches from the fan opening, mine flows smoothly from the attachment points to the fan opening. HTH!

tomatocity · 07-14-2005, 01:29 PM

Quote:

Originally Posted by Stocker

Tomatocity, I should add that my shroud does not look like the one in your pics. I don't have a digital camera, but I'll try to describe it. Rather than the sudden transition a couple inches from the fan opening, mine flows smoothly from the attachment points to the fan opening. HTH!

Yes I just checked ECE and the show a different shroud for a 4WD vs 2WD. Is a 4WD engine set back farther tha a 2WD? Thanks

70short/step · 07-14-2005, 01:33 PM

Yes 4X4 have the engine set back further

07-11-2005, 05:43 PM	#1
tomatocity Registered User Join Date: Jun 2005 Location: Sacramento CA Posts: 1,255	Fan shroud info clarification Here is information I recieved from ECE Technical Support. Does this mean that the distance between the radiator and motor is an inch less or the fan shroud is an inch closer to the motor? ---------------------------------------------------------------- Tim, the only difference between the two shrouds is the A/C model is about an inch shorter between the radiaitor and motor. ----- Original Message ----- From: Tim Olmstead To: techquestions@earlyclassic.com Sent: Wednesday, July 06, 2005 11:48 PM Subject: Technical Question Hello ECE Tech, I need to purchase a fan shroud for my 1970 C10 2WD 350 w/AC. I noticed you have two a different fan shrouds, one for w/AC (11-3901443) and one for w/o AC (3889079). What is the difference in the fan shrouds? Tim Olmstead __________________ Got bored, sold everthing. Got bored, looking for a 1960-66 C-10. Want to build my last truck.

07-12-2005, 09:57 AM	#11
StingRay Senior Member Join Date: Mar 2000 Location: Saskatoon,SK,Canada Posts: 2,476	The show is dream car garage. __________________ Saskatoon, Saskatchewan Canada

07-13-2005, 12:27 AM	#19
tomatocity Registered User Join Date: Jun 2005 Location: Sacramento CA Posts: 1,255	tomatocity, i wasn't directing that at you....just in general...I know you were just relaying the info..my fault, I need to reword my thoughts sometimes.[/QUOTE] Hey no offense taken. Glad to share whatever input we have. Better than talking to ourselves (man that would be a boring conversation for me). __________________ Got bored, sold everthing. Got bored, looking for a 1960-66 C-10. Want to build my last truck.

07-14-2005, 10:23 AM	#23
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,722	Tomatocity, I should add that my shroud does not look like the one in your pics. I don't have a digital camera, but I'll try to describe it. Rather than the sudden transition a couple inches from the fan opening, mine flows smoothly from the attachment points to the fan opening. HTH! __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

07-14-2005, 01:33 PM	#25
70short/step Registered User Join Date: Dec 2003 Location: Stockton, CA Posts: 1,579	Yes 4X4 have the engine set back further __________________ For every person with a spark of genius, There are a hundred with ignition trouble. 70 Short/Step

07-11-2005, 06:18 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	IIRC, A/C trucks came with a fan clutch, which would move the fan forward....an inch or so. This would make the space from the fan to the rad smaller, and the shroud needs to be an inch shorter too. You want your fan blades to be 1/2 in and 1/2 out of the shroud for max cooling.

07-11-2005, 07:32 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Like I said...IIRC....I am commonly wrong on details.

07-11-2005, 07:41 PM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	lol...OK If I Remember Correctly IIRR If I Remember Right

07-11-2005, 10:20 PM	#9
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	if the fan sticks out a foot from the engine, what does it matter if there is another belt and a compressor mounted up over a valve cover?

07-12-2005, 01:27 PM	#12
badpeanut Not a bad nut after all.. Join Date: Dec 2000 Location: ND Posts: 1,759	My theory is that AC trucks had 4-row radiators which are bigger hence requiring a shorter shroud.

07-12-2005, 05:52 PM	#14
matthufham Registered User Join Date: Feb 2005 Location: Carl Junction, Missouri Posts: 2,061	don't ac trucks have a long water pump, and non ac trucks have a short water pump, hence the 1 inch difference. that's how the p/o of my truck explained his home made alternator bracket.



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