Shroud with or w/o AC

[Cmillet]

Can I use an AC shroud on a non AC truck and vice versa? I've gone tons of previous post and can't find an answer. I have a 70 truck with a stock 307. Thanks.

[ChevLoRay]

I think the key to your question is where the blades of your fan are located. My understanding is that they need to be placed in the rearmost part of the shroud. If they are too far forward, they won't pull the air thru the radiator. Ditto if the blades are outside of the shroud.

Use of a long or short water pump and the spacers between the fan pulley and the fan itself, are what is going to affect where the fan is finally located.

[haminator]

I have always been under the impression that there are only 2 wheel and 4 wheel drive shrouds. No difference for A/c, however I may be proven wrong. Also there is the big block shroud. I'm not sure but a V-6 shroud sure looks like a big block shroud. Also DO NOT put a spacer behind a clutch fan, it will destroy your water pump in minutes, I learned this the hard way. I hope this rambling helped in some way.

[Cmillet]

Thanks guys. The lmc book has one with and w/o AC.

[FirstOwner69]

The original small block 2WD shrouds are two different depths. Otherwise, they are identical. The non-A/C shroud is 3/4" deeper than the A/C shroud. Therefore, the non-A/C shroud can be modified to took and function like an A/C shroud, but not the reverse. I believe the A/C shroud is actually the one to use if you have a 4 row radiator with or without A/C. As stated above, the proper shroud puts the fan blades in the correct position.

Here's a picture of the 2 back-to-back.

[haminator]

Ahh, I didn't consider the different radiator widths. Now I gotta look at my shrouds.

[davepl]

Yep, two factors at play here: fan thickness (since it has to be placed at a proper depth in the shroud hole) and rad thickness.

They're might be four shrouds:

Small block
Small block AC
Big block
Big block AC

There are also heavy duty cooling options but they probably use parts from the AC setup I'm guessing.

[haminator]

What do you know about the V-6 shrouds? I don't have a big block one to compare to but it sure looks like the pictures of ones I've seen.

[FirstOwner69]

I assume you mean I-6.
I think the original "shroud" on those was only a metal plate about a foot wide that extended from the top center of the radiator support to just above the fan. More of a safety feature than cooling aid.

[haminator]

Oh no I mean V-6. Such as GMC 305, 351 that was available in light duty trucks. I just got a 68 GMC C-30 with an Open Road Chassis mount camper with a 351 V-6. I still need to verify it is a 351 though.

[FirstOwner69]

Originally Posted by haminator

Oh no I mean V-6. Such as GMC 305, 351 that was available in light duty trucks. I just got a 68 GMC C-30 with an Open Road Chassis mount camper with a 351 V-6. I still need to verify it is a 351 though.

Duh, I keep forgetting about those. I saw 2 in the local junkyard last year too.