New Hayden Heavy Duty Low Profile Fan Clutch # 2947 is a heavy duty version of Jag Style #2765 Hayden fan clutch. My brother just saw this post from last summer on B-Bodies only. I just bought one from Summit Racing, and thought to post it on Moparts also. The new heavy duty 2947 is only about 0.035 inch longer total, so it should easily replace the standard duty Jag fan clutch #2765. After I install it, replacing the 2765 fan clutch, I'll post the results. I'm hoping for a little better summer time cooling with increased fan speed.

Informative links to check out.

http://www.forabodiesonly.com/mopar/threads/short-shaft-fan-clutch.333873/

http://www.forbbodiesonly.com/moparforum/threads/hayden-fan-clutch-low-profile.115490/

http://www.forbbodiesonly.com/moparforum/threads/txdons-67-gtx-project.116786/page-2#post-910513714

https://www.summitracing.com/parts/hda-2947

Here are the spec on the old standard duty 2765 jag clutch and new Heavy duty 2947 fan clutch.

Good info! Thanks for posting it.

Awesome! No problems in the Summer heat here, though, with the stock fan.

I just replaced my 2765 with the 2947. The prior did not have enough clutch to run my 7 blade fan, temps would creep up. Comparing the 2 sided by side there is a dramatic difference in clutch tension. I almost think my 2765 was defective.
I have not had a chance to take a long drive, it's sure to help.

Edit- Rock Auto had the best price that I found.

I had a chance to drive around with the new fan.

I had replaced my fixed 4 blade fan with the 2765. The 4 blade kept the engine right around the 185 mark with a 180 degree stat until you really drove hard, then the temp would raise up to 200-210, at which point I would start to slow down and let the cooling system catch up.

With the 2765 and a 7 blade steel hub/ aluminum blade Mopar fan, the temp went right on up past 185 and never come back down, even driving easy. When I pulled into the garage, the temp was at 220, an all time high for my car.

With the 2947, the temp went right past 185, but stopped at 195. I am thinking that is when the clutch engaged. I ran pretty hard on a bout a 20 mile mixed highway speed, traffic light situation, temp stayed dead solid.

The exhaust is too loud to hear when the fan engages, but the new model is working, where the old model didn't.

I have a 1965 Dart with a smallblock, and installed a champion three row radiator ment for a b body, which required opening up the core support about an inch and a half wider. Between the extra core and the B body sized rad, the room available for a clutch fan is not enough, leaving zero clearance for even the new shorter fan clutch the way the rad is mounted now. But all is not lost, it looks like l can get the 3/4 inch clearance I need by further trimming the core support at the top and sides, bringing it out away from the motor the max possible and still leave enough stock core support.

Thanks for posting your test results 2765 vs. 2947 fan clutch. I'll be replacing my 2765 fan clutch with the 2947 fan clutch in the near future, hoping for similar results, lower engine temps especially in the summer.

I removed my 2765 jag fan clutch this weekend. Measured it next to the new 2947 fan clutch. Noticed immediately that the new heavy duty 2947 is 1/4 inch longer total, so the clutch will be closer to the radiator. The measurement information shown on the Hayden website (posted above) shows much less overall length difference. Just wanted everyone to know, in case your radiator to fan clearance is tight already. The new 2947 fan clutch will work on my car, but is MUCH tighter clearance now. Hopefully installing will help keep the engine cooler, but have not run the engine yet, still working on re-installing the radiator....

Do these work with reverse rotation for serpentine belts?

No it will not work in reverse.

So to use this clutch (with say the mopar lightweight fan) we would need approximately 4" from the face of the pulley to the Back of the radiator. The MP lightweight fan would probably act "tight" (which is good for cooling) compared to a heavy fan since it has less rotating inertia.

I need to measure tonight, looks like a good way to rid myself of the electric dual fan set-up I have now.