[HWYSTR455]

Believe when Schurkey mentioned 'optimal' it was in reference to the fan disengaging at an appropriate rate. The HD fans engage more at lower RPMs and never fully disengage like a 'standard duty' clutch will. But obviously, a slight loss of power/HP is not a concern in your app.

I believe the bearing is larger in the HD clutches too, which help them last longer, but it's been a while since I used one.

HD clutches do have a tendency to shorten belt life, something to keep an eye on.

Many do the AC pulley 'upgrade' and overlook the fact that, depending on the year/series of pulley setup, also require the crank pulley as well to maintain proper groove alignment. On the pre-70 setups, the diff between the AC and non-AC crank pulley is about a half a groove distance different. The dreaded belt-squeal is a tell-tale sign.

New OE-type replacement fans are available, and are a safe way to go when going to a clutch fan. Originals can and do fail. If you're running over say 5-5500 RPM regularly, it's not a bad idea to use a new one over an original that's been in piles and kicked around over the years.

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