Fan shrouds - would a 350 fit in a 455

Discussion in 'The Bench' started by Utah455, Apr 15, 2019 at 10:20 PM.

  1. Utah455

    Utah455 Well-Known Member

    my guess is no, but just wanted to check to see if a fan shroud from a 1970 350 skylark would fit in a 70 455 GS. Also, are the top radiator covers interchangeable? Thanks!
     
  2. johnriv67

    johnriv67 Well-Known Member

    I’m guessing yes, but I don’t know, so don’t listen to me unless someone else says I’m right!

    As for radiator covers, I would assume yes. However, look at my previous statement if I am wrong.
     
  3. hugger

    hugger Well-Known Member

    Top rad covers are the same, people use small block shrouds all the time, but here's the issues that follows, poor cooling, extremely close to the alternator pulley, makes belt installation a pita and looks dorky,...don't do it
     
    Nailhead Ronnie likes this.
  4. Utah455

    Utah455 Well-Known Member

    Thanks for the info. My front end is a Frankenstein of parts. Trying to make heads or tails of it all. I have a 6 bladed (18" diameter) fan with a 1971 Shroud (22" diameter) with a 1972 radiator cover installed with a 1976 455 block with the long nose pump.

    I may just buy the correct part number radiator cover for 1970 and keep the 71 shroud with the 71 rubber insulators.

    Should I be using a 7 bladed fan? Are they 20" in diameter?
     
  5. copperheadgs1

    copperheadgs1 copperheadgs1

    No 7 blade fans are 18”. I’m not aware of any 6 blade fans? All 350/455 AC, heavy duty cooling and Stage1 used the 7 blade. In 71 455 used a 5 blade 20” fan and shroud was bigger. Also 70 radiator rubbers are different than 71/72 as well and there are huge geometry issues if you start mixing and matching parts. It’s a damn shame no one has been able to properly reproduce the 70 455 shroud. Strangely you could still get NOS 70 Olds fan shrouds from GM a couple of years ago.

    70 radiator top plates besides the early plastic ones are interchangeable from 70-72. Even big cars are the same. The 70 radiator cover is different in that it has one small round hole for AC bubble viewing where 71/72 has two holes. Few know this however or even care but the 70 is rare.
     
  6. BrunoD

    BrunoD Looking for Fast Eddie

    Most 7 blade fans are 18 inch,71-72 will work good,if you don't mind the little different appearance.Bruno.
     
  7. Utah455

    Utah455 Well-Known Member

    I got a 6 blade 18" diameter fan installed on this 76 455 block. No clue what is is from. Could be an Electra, Lasabre, heck even a wagon. I finally got a hold of the previous owner (20 years ago) and he said the other motor( no clue if it was original) spun a bearing and his machine shop guy had this 455 laying around and built it up. Apparently is had a stage 2 equivalent cam inside with harden seats and what not. It sounded good when I pulled the motor, was just gonna clean and paint it, but was wondering if I needed to get proper shrouds and top.

    Sounds like I may need to find a 5 blade 20" diameter fan to work with my 22' diameter 71 shroud. Oh yeah, did I mention the car is a 70 Stage 1...non matching numbers :)


    Fan 6 Blade.JPG
     
    johnriv67 likes this.
  8. copperheadgs1

    copperheadgs1 copperheadgs1

    Since it’s a Stage1 try hard to find all the correct parts. You have an AC alternator bracket and single pulley. All Stage1 had all Air conditioning pulleys even without AC. That fan is a weird one.
     
  9. Utah455

    Utah455 Well-Known Member

    What do you mean single pulley? Does the AC compressor belt off the alternator pulley? The crank has three grooves, my assumption was one for the Alternator, one for the AC and one for the power steering. The AC compressor was in the trunk and I have the AC brackets in a box. I gotta find a diagram
     
  10. 87GN_70GS

    87GN_70GS Well-Known Member

    There are GM 20" 7-bladed fans that were put in bigger cars, trucks etc. They are for sale on ebay, in the yards etc. I'm using one with the larger 22" shroud opening
     
  11. 87GN_70GS

    87GN_70GS Well-Known Member

    Also, 70's mopars had a 7-blade 20" fan that will bolt up to our clutch
     
  12. copperheadgs1

    copperheadgs1 copperheadgs1

    Now we are going way far away from what was used in a Buick. No 22” fans were used on early 70’s big cars.
     
  13. copperheadgs1

    copperheadgs1 copperheadgs1

    Yes , to run an AC system you need a double pulley for the alternator. AC rear Belt goes above rear groove of alternator pulley and around water pump and crank pulleys. Although a 70 AC belt doesn’t ride in the groove it has to be there for spacing. It sounds like other pulleys are correct. What are the part numbers stamped on those pulleys? My bet is someone traded in your original alternator and new didn’t swap the pulley. New ones are not correct for your application.
     
  14. copperheadgs1

    copperheadgs1 copperheadgs1

    EF95E047-6995-4E4F-87EF-20631C329099.jpeg Here is the correct pulley you need. It was used on Stage-1 and heavy duty cooling cars as well with or without AC
     
    Utah455 likes this.
  15. copperheadgs1

    copperheadgs1 copperheadgs1

  16. copperheadgs1

    copperheadgs1 copperheadgs1

    What did that lower radiator hose come off? That thing looks ridiculously long. It must bump everything?
     
    Utah455 likes this.
  17. Utah455

    Utah455 Well-Known Member

    Do they sell alternators that have that double pulley already installed? Or do you have to find the pulley separately and mount yourself?

    The pulleys I have are 1235777 and 1235778 which appear to be 71-73 vintage
     
  18. 87GN_70GS

    87GN_70GS Well-Known Member

    You must've misread. 20" fans were used.
     
  19. copperheadgs1

    copperheadgs1 copperheadgs1

    Yes I think you are right on the fan.,. I misread. you are correct the pulleys you mentioned are 71 pulleys not 70. . Now it really gets tough. What number is stamped in the upper alternator brace? 7o is different than 71 and later. To run those pulleys you need the 71 and up number as well as the 71 lower Alternator bracket. People mix and match parts all the time assuming it’s a 455 so it must fit right? Wrong. Also what power steering pump and pulley are you using? You have a picture? I can post all correct part numbers to work for a 70. The lower combination alternator/AC bracket for a 70 being different than 71. Problem is there aren't any part numbers on those. Do you plan on running AC for sure? Upper triangular AC compressor bracket is different as well. Again. No part numbers. My guess since your car is not matching numbers is someone just swapped in a complete 71 engine. Is there a part number on the intake manifold and heads under the valve cover? Sounds like you have a 70 Stage-1. It would be a shame not to find all the correct pieces for a 70. ......
    Answering your question on store bought alternators. The answer is no. None of them come with the double pulley. I hope I am not confusing the crap out of you. Using the wrong stuff or mixing the years will cause belt geometry nightmares.

    I will post part numbers later.
     
    Last edited: Apr 18, 2019 at 7:11 AM
  20. copperheadgs1

    copperheadgs1 copperheadgs1

    Another observation. The upper alternator bolt is on backwards. It should go in from the rear and into the threads of the alternator. The way it is on would require a nut to be used in the back. No nut was used. Someone could have stripped the threads in the alternator is my bet.
     

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