My 71 Duster work in progress

The stupid thing still gets hot. 220 in the garage before I turned it off.

Maybe it's the fan. It didn't seem too enthusiastic about sucking in a paper towel held in front of the radiator. Maybe it's not getting enough air???

I've got a flex fan that came on the 400 that I could try in place of the 7-blade /6 w/ A/C fan that's on it.

I might need to monkey with the timing and carb too but it's starts/runs good enough that I doubt that would be out far enough to make it overheat.
 
68R/T said:
Definitely sounds like airflow issue.
Click to expand...

In addition to the flex fan I've got an OEM electric fan from something or the other that cooled the roadrunner at the track, but I think it might be too wide for a 22" radiator. I'll dig those two fans out and see if they help anything. FWIW the flex fan is too large to fit inside the shroud so I might not mess with that. The e-fan, being an OEM part, has a shroud and rubber seal.

Another gotcha are the Cold Case shroud attachments - the factory style shroud fit, but the attachments stand off the radiator about an inch. So there's a gap all the way around it. I will probably try to fill that with some cardboard and gorilla tape - that might help. The fan is toward the engine side so it seems plausible that the fan is pulling air from around the shroud as much or more than it's pulling through the radiator.

At least I don't have to drain anything to work on it now.
 
Experiment 1 - closed off the top and bottom gap between the shroud and the radiator. Didn't help, still not a lot of suction at the front of the radiator.

I looked at the flex fan, it won't fit inside the shroud.

The e-fan from the A12 looks like it might fit in the radiator frame (without taking the shroud off) if I can figure out a way to mount it. I used those plastic through the radiator things on the roadrunner but there doesn't look to be room to shove those through the fins of this new radiator. I held the wires to the radiator and the thing seemed to want to take off. It moves a lot of air. I didn't see any OEM looking marks on it so maybe it was an aftermarket fan/shroud kit of a thing.
 
I wouldn't leave it there - just seeing if a different fan would make a difference. The thing is dangerous because it is too big to fit in the shroud and sticks up above the core getting in the OW MY FINGERS! zone, or at least it did when I first got the car with a 400 in it.
 
So I took the fan and shroud off.

The e-fan is the perfect width, I can get two of the mounting locations bolted to the radiator and it sits flush up against the fins. but it's 2-3 inches short of covering the rad from top to bottom. I don't know if that is a problem but it would seem to at least be less efficient than a full size shroud. There is about 1/4" clearance to the waterpump, but I didn't have the pulley in place either so that and the bolts may eat that clearance up. I connected it to the battery and did the paper towel in front of the radiator test and it basically snatched the towel out of my hand. Much better than what I started with, but the fan is running full steam ahead so of course it will move more air than the engine will at idle/low engine speeds. I have no idea how many cfm it is pulling.

The flexfan is a Flexalite with 18" aluminum blades riveted to a steel center. It's not one of the ones with "pointy" shaped blades. It looks pretty old and well used so I don't trust it long term. It fits in the shroud, but not with the fan/shroud mounted, so the fit might change. It seemed too high bolted to the 400 but it also seemed like that engine was high in the front so that might have caused that.

The waterpump pulley is abut 6-7/8" outside-to-outside. IIRC I bought that, so it should be the right one for a V8 A-body with PS, but I also can't find any part numbers on it. The crank pulley is basically the same size but I need to measure it to be sure but forgot to do that. I recall that being a part I had laying around, probably from a F-body. I would rather the crank pulley be larger than the waterpump pulley to overdrive the water pump but I don't know if that's possible with available parts.
 
I took a break at lunch and stuck the pulley, bolts, and the e-fan on there. There's plenty of room between the pulley and fan.

If it works I will need to adapt it to bolt the bottom of the fan to the radiator but it's at least testable right now. Will probably wire up a switch, run the car up to about 190, turn the fan on, and see if the temp keeps going up or not.
 
I wired up the fan on some alligator clips, ran the car until it was at thermo temp, and turned the fan on. It didn't exactly stop the heat from rising but it did seem like it had better control of things. Remember it's idling in the garage, not driving down the road.

So now I'm mostly convinced the fan is the problem, at least until I take a spin to see how it acts in the real world. I need to do a safer job of wiring the thing first.
 
It's been raining so no driving action, but I did install a switched ground wire to the fan negative and added a fused wire from the battery to the fan. That's good enough for now.

I've only got about 3" between the rad and the pulley, and there are basically no shrouded electric fans that will fit in that space, so that one needs to keep working for a while because it will be hard to replace if I decide to stick with it.
 
Since the electric fan doesn't really fit right, I looked around for mechanical fan alternatives:

I've found several 2863 216 fans on e-bay
1746360848760.png
That is the largest pitch listed in the 68 parts book, but note it's not in the A-body column, B-body only.
They are mostly rusty as heck and expensive for the work they would need. Mancini has a repop but it's yikes $286+shipping+tax.

340s had
1746361847503.png
The 215 was used on Hemi 4-speeds too.

This is what I had on it to begin with, basically a flat fan.
1746361067002.png

There is a repop GM 18" fan available, number 3947772, with a 2.25" pitch (same as 340), 3947772 Fan for sale | eBay. That is about $120 and up.

If I go with any of those options, with just 3" between the pulley face and the radiator core, I will need one of these . More Information for HAYDEN 2947

"Turns the fan 70-90% of the shaft speed when engaged for increased cooling
Turns the fan 25-35% of the shaft speed when disengaged
Used with deeper pitch fans (2-1/2" of pitch)
Land and groove design with up to 27 square inch of working surface
Identified by finned aluminum face plate and thermal spring on the front"

Not 100%? That's a reason why I don't really like a clutch fan.
 

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b-body-bob said:
Mancini has a repop but it's yikes $286+shipping+tax.
Click to expand...
I found the repop 216 fan for as much as $50 less.

The clutch adds about $60 to that, plus tax, plus shipping.

So all told it's going to be over $300.

This seems like the way to go, which of course it does now that I've got the electric fan installed. :)

I measured a little better and found I have about 3-1/2" between the water pump and radiator core.
 
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