What fan clutch can be fitted to a 1959 401. What brand are you guys using? Do you have a part number?
From what I can see from my parts reference, all 1959 Buick's with air conditioning used GM Part No. 1353190 for the fan clutch. I think others should chime in regarding if I got this right or not.
Update. I got a hold of a Hayden 2797 fan clutch and it bolts up to the water pump. The snout protruding from the water pump that fits into the fan clutch was .665 and the hole in the fan clutch was .625. My friendly machinist enlarged the hole and it just slides on. So I ordered a fan today, seven blade 20 inch diameter.
That fits a LOT of applications! Rockauto has it listed for various models from 1960 into the 80's and 90's. When I was junkyard hunting, I got one from a mid 80's Regal V6. I had a harder time finding a smaller diameter fan, got one from a Cadillac.
Summit lists that as a "Severe Duty" clutch. Coupled to the fan you ordered, it's never going to properly disengage. It'll be noisy and take excess power. Even a "Heavy Duty" clutch would probably be too much. You need a "Regular duty" clutch. Folks install "HD" and "SD" clutches because they have failing cooling systems, or they don't understand how fan clutches are supposed to work. Very few cars got--or need--the stiffer clutches.
