Need some advise on fan clearance please

[Hair]

71 GMC 2WD 1500
Put an 89 model 454 in place of Inline 6 and I'm having an issue with the fan clearing the radiator, See pictures, the fan clutch is 1/8" to 3/16" away from radiator. I have 3.5" from radiator to water pump pulley face.
1. Is this too close, I'm assuming it is???
2. What do I need to do here?
3. Can I go with a short water pump and fix it, but if I do, wont I have to buy different alternator brackets and damper pulley too? Because the Alternator cant go back an inch or so where it is, it would hit the block.
4. What about an electric fan? Maybe I could squeeze one in there? I watched a Summit video that recommends a 4,500 cfm fan for a BBC - that's like $300 plus an install kit. I'd really rather just run a clutch fan and forget about it, if I can.
5. Help me please, what is the best route to go here, is there a simple fix?

[Hair]

Ok, been looking around. I am considering ordering a low profile heavy duty Hayden Fan clutch P/N: 2947 - this will give me about 3/4" between the clutch and the radiator. An easy fix for $70. What do you guys think, is this a good idea? Will that work? Is 3/4" enough clearance?

[Steeveedee]

I forget which part number clutch I have, but it is the severe duty model. It's about 3/8" from the radiator. The fan didn't line up properly with the shroud so I made one. This truck ran hot it's entire history, but it doesn't anymore. It's all stock except that I added an aluminum radiator (same size as the old 4-row brass one). After all the working on it, it turned out that the old thermostat didn't flow enough, so I bought a high flow thermostat. The old thermostat worked fine, but just didn't allow enough flow.

[jimijam00]

I think 1" is ideal, so 3/4" should be fine.

You'll be running a shroud that seals against the rad and has the fan blades 1/2 in and 1/2 out of the shroud, right?

[Hair]

I haven't even attempted to put the shroud on yet. I have the 6 cylinder shroud that I plan to use, it is very shallow, so I'm thinking it will fall into the "half in and half out" realm. The shroud is a one piece design. I will have to remove the radiator, install the new clutch, then slip the shroud over the fan and let it hang there, install the radiator, then pull the shroud back up against the radiator before I can really see how it will fit. If it don't fit, I'll have to figure out something else. My new fan clutch is supposed to be here tomorrow, so hopefully I will know how things fit by tomorrow afternoon (Wednesday).

[Steeveedee]

That's how I have to do mine. The clutch is close enough to the radiator that I have to pull the thing off to change fan belts. It's always been this way since I got it. The frame adapters appear to be in the proper position (I looked at a ton of pictures) and I have the short water pump like came on the truck in '70.

[MARKDTN]

Moving the engine back not an option? Assume you already have driveline and exhaust installed? If not, low profile electric fan. Apparently a 2003 Neon has a dual fan that is 3.4" thick and cools well. Maybe the pulley would end up in the middle and have more than .1"

[toolboxchev]

Too close when in comparison to stock, will not pull air from outer edges.

May cause cooling problems. Your results may vary as my opinion is based on a stock truck.

My opinions may vary........

[Steeveedee]

Originally Posted by MARKDTN

Moving the engine back not an option? Assume you already have driveline and exhaust installed? If not, low profile electric fan. Apparently a 2003 Neon has a dual fan that is 3.4" thick and cools well. Maybe the pulley would end up in the middle and have more than .1"

I can't answer for Hair, but I considered it on mine. That's more work than i want to do, unless I pull the engine and trans for a rebuild. It would require adjustments to the trans shifter and shortening the exhaust pipes, new trans cooler and radiator hoses (I think). The driveshaft has a lot of spline showing (which made me consider moving the engine back- I don't think it should have that much showing). Probably something else but off the top of my head, that is about it.

[MARKDTN]

Originally Posted by Steeveedee

I can't answer for Hair, but I considered it on mine. That's more work than i want to do, unless I pull the engine and trans for a rebuild. It would require adjustments to the trans shifter and shortening the exhaust pipes, new trans cooler and radiator hoses (I think). The driveshaft has a lot of spline showing (which made me consider moving the engine back- I don't think it should have that much showing). Probably something else but off the top of my head, that is about it.

Are there not 2 sets of holes on the frame? I don't know BB stuff as well but the I6 mount holes are different-further forward-than SB (and BB?) mount holes I was pretty sure.

[Steeveedee]

Originally Posted by MARKDTN

Are there not 2 sets of holes on the frame? I don't know BB stuff as well but the I6 mount holes are different-further forward-than SB (and BB?) mount holes I was pretty sure.

My understanding is that the BB uses the forward holes. The engine and trans were out for a rebuild many years ago, and I was thinking that they got put in at the forward position. It'd be real nice if the fan was away from the radiator. But again, all the BB pics I've seen have the frame adapters in the forward holes. There is room to move the engine and trans back.I ain't going there unless I rebuild or replace. It's a lot of work.

[bigmac73]

I would ditch the fan clutch and just run a straight fan, with the thinnest spacer allowed I have never had a problem doing that. unless some one disagrees???

[Hair]

I didn't even think of running a straight fan, I thought that a clutch fan cools better, but I suppose your correct. I could have saved room easily with a straight fan and I guess all the clutch does is save on power of spinning the fan when not needed?? Anyway, I could have used this advice last week before I ordered the new clutch.

I got the low profile clutch in and installed today, and I have a good 3/4" now. The fan sticks out of the shroud about 3/4 of the blade instead of 1/2 of the blade, but I'm going to run it and see how it goes.

My new headache is the wiring, the I6 had the alternator on the lower driver side and the 454 has the alternator on the upper passenger side. I'm going to have to do some wire splicing and add some length and run them over the radiator or something. I gave up for the night.

[Mike C]

The 68-72 big block trucks used a different water pump pulley setup than the later 454's. The short pump and the correct brackets help solve most of the clearance problems with the radiator.

But those parts can get expensive fast along with the big block fan shroud. But it is the right way to do the converison and keeps the alternator on the drivers side.