Big Block/4 row shroud (73-80)

[eric8]

I finally decided to swap my small radiator in my 77C 10 for the big block radiator. I have the new metal top plate and the wider mount cushions, as well as the BB fan shroud.

My questions are about the mounting of the shroud. The bottom of my original small block shroud lid into some U-shaped metal clips on the bottom core support, and then the top of it bolted to the radiator top plate. As you can see in the photo of the big block shroud, it has several mounting holes along the bottom of it, and I don’t know what they are used for? The factory illustrated parts book seems to be no help.

[eric8]

Mockup photos from today with the lower shroud tabs sitting in the factory SB shroud clips. Seems to have a gap between the shroud and radiator. Is this normal? Also, there’s a middle mount tab on the upper portion of the shroud with nothing to bolt to. Thoughts?

I can find nothing that shows the factory 4 core would use any different lower mount clips than the SB shroud used. I have the 4 core top support, shroud, and wider cushions. The fan shroud is a reproduction.

[eric8]

Well I *think* I have part of the problem resolved. The original big block shroud p/n for square bodies was 06262163. That shroud was flat along the bottom and did not have the lower two tabs with bolt holes sticking down. That shroud got superseded to p/n 14021289 (direct replacement according to GM) which has the two tabs along the bottom along with the middle top (unused?) mount tab.

As you can see in the first photo of a 6262163 (still with the clips it rides in intact) the flush bottom would allow it to sit lower and ride flush with the core support top plate. I could trim those bottom ears off of my reproduction 14021289 and mimic the earlier p/n. I still don’t know what would fix the gap along the sides though.

[RustyPile]

Something like this might work..

https://www.oreillyauto.com/detail/c...ersal%29&pos=2

[eric8]

Well I hacked off the bottom ears of the fan shroud which made it sit perfectly flush with the radiator top plate. Found a pic of a 76 factory big block on a Bring A Trailer auction and apparently the side gap is normal (see below).

Now my only issue is the factory 350 clutch fan doesnt extend into the shroud as it should. I guess the spacing of the big block water pump is different, or maybe they used a longer shaft going to the fan?