CQR

What is everyone using for a fan clutch? O.E is discontinued and my AC Delco one lasted a little less than a year. The aftermarket world of fan clutches really seem to blow. Anyone have a trick on using a newer model one that hasn't been discontinued thru GM?

I need one for a 67 400 A/C car.

MDchanic

Hayden 2797.

It'll blow the hood of your car.

I love mine - Roars like a P-38 taking off for 5 minutes or so after starting the engine, then settles down, but comes right back on if she starts to get warm.

I can idle all day on a 100° day, or spend the day creeping through traffic, no problem.

Why go halfway?

- Eric

CQR

Thank you. I'll give it a shot.

CQR

Got the unit (reboxed under another number). And its too tall. Its right around 3 3/4" tall. That gives me about 1/8-1/4" to the radiator when installed. Will work perfectly in a perfect world. not gonna see what happens with body flex pulling into a parking lot. I need something shorter. Any other Ideas?

MDchanic

Sorry about that, CQR.

It looks like the earlier cars have less clearance between the radiator and the fan - likely because the lower-end cars didn't use fan shrouds, and the closer clearance would have helped move air better without one.

I checked two different sources, and they both showed the fan clutch for your car as having
a fan height (distance from the water pump) of 1.51", and
an overall height (distance from the water pump to the end of the clutch casting) of 3.09".

The 2797 is listed as having
a fan height of 1.63" and
an overall height of 3.65",
so it looks like those fins that stick out from the front are about half an inch too long.

For whatever it's worth, the 2747, which is the "heavy duty" clutch, shows
a fan height of 1.62" and an overall height of 3.34",
which saves you a quarter of an inch.
Depending on your clearance comfort level, you may wish to try it.

Frankly, I'd probably try the 2797, install it without a shroud, watch it closely as you revved the engine, then switch it off and try jacking up the car from different locations to duplicate different loads when cornering, braking, or hitting bumps - you may find that it never touches, and you can get a lot more body flex by jacking it in an odd place than you can while driving.

Once again, sorry - I didn't realize that there was so little space up there on the earlier cars.

- Eric

CQR

Thanks Eric,

I looked at Haydens spec guide and found the same info. Since the Delco unit I took off was a standard duty thermal, and worked ok when new, I'm gonna gamble on the 2747 and see if it can keep her cool.

Lady72nRob71

If the car did well with the standard duty one, you may be better off to replace it with that. Just make sure it is thermal.

I got a 2747 to put on Lady (350 & AC) and the fan did not have enough air resistance to disengage it properly. Fan is 19", 6 blade, 2.25" pitch. It seemed to be engaged at any temp below 2200 RPM. This made for lots of noise and power loss upon acceleration.
I took it off and installed a NOS Delco one for this application and had much better results.

I just learned all this recently - I did not know there was as much science in this concept. The HD clutch were for larger fans with more blades or deeper pitches, to move more air in demanding conditions.
Try the standard duty Hayden first.

MDchanic

Good point, Rob. I've got a 7-blade 19" fan on mine, but I could imagine it not disengaging with a lesser fan.

- Eric

CQR

Good input Rob. I was installing the 2747 when Eric replied. Its on, and I don't have enough run time on it to make a determination yet. Mine is also a 19" 6 blade. we'll see how it goes.

jag1886

If your 67 uses that little short clutch my 65 does then no one makes the correct height after market, I found an original at PhillipsMuscleCar parts, he did have 2 of them when I got mine, they are very pricey but it's the right one.

MDchanic

I'm interested in knowing how it works for you.

I'm a "bigger sledgehammer" guy, so I just went for the biggest clutch they made.

As I said, I'm very happy with mine - it roars for about 5-10 minutes after starting, but then settles down and is nice and quiet, unless it's needed, in which case it blows a hurricane.

- Eric

ps: I looked at mine, and I've got 2-3" between the ends of the fins and the radiator on the '73 B-body.