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| | | | Joined: Jan 2013 Posts: 2,232 Moderator: Interiors, Texas Bolters, Name that Part | | Moderator: Interiors, Texas Bolters, Name that Part Joined: Jan 2013 Posts: 2,232 | I just installed the fan blade from my 216 onto my 235 and my fan is 3/8” away from my radiator.
Is this too close? If it is, how much do these old fans flex?
Chris | | | | | Joined: Jan 2022 Posts: 2,436 'Bolter | | 'Bolter Joined: Jan 2022 Posts: 2,436 | Not until you need to change your fan belt.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
| | | | | Joined: Jan 2013 Posts: 2,232 Moderator: Interiors, Texas Bolters, Name that Part | | Moderator: Interiors, Texas Bolters, Name that Part Joined: Jan 2013 Posts: 2,232 | Bill,
Is only 3/8” at the top due to being 1/4” higher then the fins. | | | | | Joined: Feb 2016 Posts: 1,982 'Bolter | | 'Bolter Joined: Feb 2016 Posts: 1,982 | Not only do we have to be concerned about the fan blades flexing at different rpm, but also the flex of the frame/radiator core support. I think 3/8" is too close.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
| | | | | Joined: Oct 2021 Posts: 6,697 'Bolter | | 'Bolter Joined: Oct 2021 Posts: 6,697 | My stock 216 with stock fan and stock radiator is 7/8" at it's closest point.
How much flexing does the stock , 4 blade fan do at 2500rpm? What is different about the 216 fan compared to the 235 fan?
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
| | | | | Joined: Mar 2014 Posts: 4,479 Moderator, Electrical Bay | | Moderator, Electrical Bay Joined: Mar 2014 Posts: 4,479 | The original fans weren't flex fans, although at higher rpms they might change shape a little bit. In your case, I wouldn't spend one second worrying because centrifugal force will be your friend. Because of it, if the blades change shape at all, they may go flatter.
Many of the original blades will be out of balance and if that's the case you can expect your water pump to not last as long. If you have any imbalance it is a problem for the shaft, bearings, seals. Are you saying your fan blade sits higher than the radiator fins? Up where the seam is? Sorry but from your words it seems like that's what you're saying but I'm not certain. Ideally you want the fan to be located in the center of the radiator fins...below the seam.
Last edited by Jon G; 05/26/2026 1:29 PM.
~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
| | | | | Joined: Jan 2013 Posts: 2,232 Moderator: Interiors, Texas Bolters, Name that Part | | Moderator: Interiors, Texas Bolters, Name that Part Joined: Jan 2013 Posts: 2,232 | I was able to figure it out. I raised the radiator 1” and I now have plenty of clearance! I’m comfortable where it’s at now.
The new blade sat 1/4” above the fins before raising the radiator. It’s centered better now.
Last edited by ndkid275; 05/26/2026 5:06 PM.
| | | | | Joined: Mar 2014 Posts: 4,479 Moderator, Electrical Bay | | Moderator, Electrical Bay Joined: Mar 2014 Posts: 4,479 | Good to hear. Is your front end not mounted yet?
~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
| | | | | Joined: Jan 2013 Posts: 2,232 Moderator: Interiors, Texas Bolters, Name that Part | | Moderator: Interiors, Texas Bolters, Name that Part Joined: Jan 2013 Posts: 2,232 | I just disconnected the radiator and slid it up. | | |
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