No, the standard fan for A/C and HD cooling was an 18" 7 blade clutch fan. The 1971 and 72 shrouds had a bigger opening, so I would use the bigger 20" 5 blade clutch fan.
Hi everyone,
I have Non clutch 7 blade fan and 7 and 5 clutch driving fans, I guess original fan for 455 with AC was 5 blade clutch drive fans, now my question is witch system is better for 455 stage 1 engines, Original 5 blade or non clutch 7 blades? I want to use 160 degree thermostat and my radiator is new but it is copper radiator.
No, the standard fan for A/C and HD cooling was an 18" 7 blade clutch fan. The 1971 and 72 shrouds had a bigger opening, so I would use the bigger 20" 5 blade clutch fan.
Larry
1970 GS455 Stage1 Race weight 4025 lbs.
TSP 470, 602 HP, 589 TQ
MT headers, Gear Vendors Overdrive
Best E.T. 11.54 Best MPH, 116.06
1998 Riviera SC3800
Thanks Larry, My GS is 1974, In fact Century Gran Sport 455 Stage 1, I haven`t exact 1974 manual but in 1975 manual that I have 455 engine with A/C had 20" 5 blade clutch drive fans and my car have same and 455 engines without A/C had 18" 5 blade fans. Also 18" 7 blade fans are for 250 Cu. In. engines with A/C in this manual. Also all A/C engines have clutch drive fans and all less A/C engines have water pump direct drive fans.
According to this manual I guess 5 blade original fans have better air flow than 7 blades and clutch drive fans can act better than non clutch ones. But I want to know if anyone have any experience of using another different fan system.
I have a 1974 Chassis manual, and yes, it looks the same as 1975. The 5 blade fan is 20". The fact that it is 20" is WAY more important than the number of blades. Your fan shroud opening is likely 22". Using an 18" fan, well, it's obvious why that would not be as good. Clutch fans are way better than fixed fan designs. They cool better when the engine needs it, and they use less power.
BTW, you should have a 74 Chassis manual, it isn't like they are hard to find. This is a screaming deal,
https://www.ebay.com/itm/1974-Buick-...Xq1-:rk:3:pf:0
https://www.ebay.com/sch/i.html?_fro...anual&_sacat=0
Larry
1970 GS455 Stage1 Race weight 4025 lbs.
TSP 470, 602 HP, 589 TQ
MT headers, Gear Vendors Overdrive
Best E.T. 11.54 Best MPH, 116.06
1998 Riviera SC3800
Thanks Larry,
I will install original 20" 5 blade with a new clutch. Hope they work at best.
When choosing your clutch, you will probably want the HD one for a/c.
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Any thik big clutch fans are heavy duty or I must check the part numbers? I have both of them one like the original shown on original manual and another thiker one that I bought years ago for my classic chevy Blazer. Both Made in USA.
An obviously heavier looking one from a blazer may physically fit, and you could use it. It may be a level heavier (rated as severe duty) than you may want. If you get too heavy duty, the fan will make more noise than you want. I you have an operating fan clutch try it with that first then if you have to order one, deal with it.
https://www.haydenauto.com/featured%...s/content.aspx
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