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Technical 471 Disassembly

Discussion in 'Traditional Hot Rods' started by Model A Mark, Sep 11, 2019.

  1. Model A Mark
    Joined: Apr 30, 2008
    Posts: 1,251

    Model A Mark
    Member
    from dallas
    1. Holley 94 Group

    Hey guys, Im trying to take a 471 roots blower apart, I took the end covers off, took the fastening screws, 2 pur bearing plate, the bearing plates came lose but only came lose a tiny bit, seams like there is a clip or snap ring or some thing holding the are the blower endplate bearings pressed on to the rotor shafts ? I dont see any way to get a hold of the bearings to pull them ..
    Ive looked everywhere even here, and cant find a video or tech about taking these apart ..
    Thanks
     
  2. saltflats
    Joined: Aug 14, 2007
    Posts: 9,354

    saltflats
    Member
    from Missouri

    If you are talking about the bearing end plates, clean the gaskets off, you will find a screw in a covered hole.
     
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  3. Model A Mark
    Joined: Apr 30, 2008
    Posts: 1,251

    Model A Mark
    Member
    from dallas
    1. Holley 94 Group

    I got those out already, guess I called them Fastening screws ..
    Thanks IMG_2807.JPG
     
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  4. saltflats
    Joined: Aug 14, 2007
    Posts: 9,354

    saltflats
    Member
    from Missouri

    If you have that screw out, then you need two pullers like you would use to remove a crank damper.
    Install over each rotor and work back and forth to press the rotors out together.
     
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  5. Desoto291Hemi
    Joined: Apr 21, 2009
    Posts: 512

    Desoto291Hemi
    Member

    You said you removed both screws from each plate?
    Have you pulled the gears yet?
    Sorry,,,just reread your post,,you did remove all the screws already.
    I have the best luck by pulling the front gears,,,,and then working the plate off the front side first.

    Tommy
     
  6. Desoto291Hemi
    Joined: Apr 21, 2009
    Posts: 512

    Desoto291Hemi
    Member

    Then,,,remove the rotors and rear plate together.
    Usually,,,the rotors can be persuaded to come out of the old bearings by tapping them with a brass punch,,,or a socket of the correct size.
    They’re usually just stuck somewhat from being assembled for many years.
    And plenty of pics helps to diagnose any problems as well.
    Make sure you take a stamp or center punch and mark the front plate and the rear plate to which end it mates to.
    I just started taking this one apart about a week ago

    Ask all the questions you need,,,there is a lot of helpful people on here.
    Good luck.

    Tommy
     

    Attached Files:

    Last edited: Sep 11, 2019
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  7. ronnieroadster
    Joined: Sep 9, 2004
    Posts: 699

    ronnieroadster
    Member

    The bearings are tight on the shafts so removing them will take some effort. What i do is tap the rotors out from the back first. To do this i use a socket that fits inside the bearing then i tap on the socket alternating from rotor to rotor until the two rotors come out of the rear bearing plate. The rear bearing plate bolts are not removed when i do this But the front plate bearing bolts have been removed of course. This way everything comes out the front of the blower case. The same way the assembly goes back in front to rear. Once i have the front plate with rotors still in the bearings out of the case i then use a press to push the rotors out of the front bearing plate. When removing the front gears its important to mark the gears to each other so the timing is kept correct. Also identify each gear to the rotor its on when its time to reassemble everything getting the timing correct will be much easier. Be careful you may find shims behind one of the gears these are used to get the rotor clearance correct.
    Ronnieroadster
     
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  8. Good info from Ronnie as usual.
     
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  9. Model A Mark
    Joined: Apr 30, 2008
    Posts: 1,251

    Model A Mark
    Member
    from dallas
    1. Holley 94 Group

    Thanks everyone for the replies,
    driving the rotor shafts from the rear worked,
    I know the scratches in the case suck, Im just not sure how bad they suck.
    Is this case usable ? I would think so as long as nothing is rubbing or touching anywhere as it spins, I know it will lose some boost, but so much as to make it none usable case ?
    Weird how the rotors dont look near as bad as the case does .. IMG_2818.JPG
     

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  10. ronnieroadster
    Joined: Sep 9, 2004
    Posts: 699

    ronnieroadster
    Member

    The scratches really wont hurt a thing including boost for a street engine. Just use some sandpaper to remove any high spots down do this by hand. The filter if any was used was not very good thats what small dirt will do to the surface.
    Ronnieroadster
     
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  11. 270ci
    Joined: May 17, 2010
    Posts: 345

    270ci
    Member

    As mentioned already, those case scratches will only hurt performance a bit, but yours is one of the worst I've seen.
    However, looking at the pics of your rotors, it appears someone has sanded the rotor edges quite a bit in the past. I would check your rotor to case clearances and rotor to rotor clearances up the inside (you'll need to reassemble the blower to do that), before I spent a bunch of time and money to rebuild and put new bearings/seals in this one. If appearances are correct then your clearances could be excessive and out of spec, which will hurt performance more than your case scratches.
     
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  12. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 887

    19Eddy30
    Member
    from VA

    If there where shims behind gear , make sure you put them back under the correct gear, the shims set the rotor to rotor timing/ Clarence . Those scratches Not big deal , just lightly sand like mentioned before , when you Reassemble to tighten gear bolts stick a rag inside rotors and torque , what size motor are you install 4-71 on, bower sizes are like carb size ,
    4-71 Max boost is around 5psi on 350 cid, carb size will need to be around 750-830 on a motor with a few sizes over stock cam @ about max 6500 motor rpm
    If New Rotors are installed the blower will have to be re-sit up , rotor to bearing clearances , rotor to case, Etc. a lathe & mill required
     
    Last edited: Sep 13, 2019 at 4:27 PM
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  13. Model A Mark
    Joined: Apr 30, 2008
    Posts: 1,251

    Model A Mark
    Member
    from dallas
    1. Holley 94 Group

    Eddy, there where shims behind the right side gear, I zip tied them to the gear for now .. its going on a 286 flathead .
    Thanks 270ci .
     
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  14. Model A Mark
    Joined: Apr 30, 2008
    Posts: 1,251

    Model A Mark
    Member
    from dallas
    1. Holley 94 Group

    Thanks ronnie, crazy that dirt could do that ..
     
  15. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 887

    19Eddy30
    Member
    from VA

    E91C0C5D-D25F-4917-BEAA-AFB4A0FE67C8.png B3221B21-8A78-47AB-8607-C59EA7E6C586.png 4AF9C2AD-7735-4FF3-91B3-AE559C051396.png
    4-71 perfect for that motor , watch your pulley combo /Ratio, the smaller cid more boots it will make . Carb /carbs cfm's will be 600-700 , root blower with carb/carb's on top like cfm's but you can go to big , if you use v-pulley instead of 1/2 or 8mm drive belts you can Measure Diameter pulleys To get the V-belt pulley size for that boost combination needed.
    "BOOST" blower size chart are just a reference number ,they are not Exact, just a Guide

    I built my first blower with help of Norma ( I think that was her name)@ BDS about 30years ago over the phone before internet , blower was completely apart in a box , nothing marked , off of a FC from 70s . Wants you see & under stand the parts And clearances you can build one with all brand new parts, including virgin case and endplates .I learn/shown By Littlefield
     
    Last edited: Sep 13, 2019 at 7:14 PM
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  16. Model A Mark
    Joined: Apr 30, 2008
    Posts: 1,251

    Model A Mark
    Member
    from dallas
    1. Holley 94 Group

    Eddy, do you know where I can get information and specs on where and how to check for clearances ?
     
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  17. big duece
    Joined: Jul 28, 2008
    Posts: 5,524

    big duece
    Member
    from kansas

    Gary Roushkolb in Wichita, KS rebuilds these in his retirement. Drag racer for 40+ yrs. 316 393 1105 I am sure he could give you some pointers.
     
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  18. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 887

    19Eddy30
    Member
    from VA

    Model A mark , this Might help you.
    Clearance is checked between the leading edge of the drive rotor and the trailing edge of the driven rotor. This should ideally be around .008". You will want to check front and back and all three rotor sets.
    Are you going to be replacing any hard parts ? If no just seal gaskets . Nothing wrong with a loose Clarence blower on street or low Hp race motor , "Loose clearances " lobes-to lobes, case to lobes , Rotors to front to rear end plate as long as rotor are not moving back & fourth. When Re-stripping Blower rotor lobes are so tight you have to use barker bar to turn , wants started up it will loosen up but still takes two hands on pulley to turn with no belt. If you install to small of a blower on , you will get to a point that blower will max out on boost , & to big of blower will heat up because not moving air fast enough , like 10-71 On sb's .
    I Kind of & do my own thing , experiment .
    Back in early 90's when a lot of guys where using
    Serpentine belt on Under hood blowers 177 vortex , Paxton's they would slip the belts , I contacted RCD , was using /had them make 8mm GT pulleys 1.250 to 2.000 wide , No Slipping , but I did twist/bang a few rotors on 177
     
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  19. Model A Mark
    Joined: Apr 30, 2008
    Posts: 1,251

    Model A Mark
    Member
    from dallas
    1. Holley 94 Group

    thanks for the help guys, i really appreciate it..
    I guess Im fixen to tackle Pruning the case now that I know its ok, , this should be fun ..
    thanks again and Ill post progress ..
     
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  20. akoutlaw
    Joined: May 13, 2010
    Posts: 706

    akoutlaw
    Member

    I use a table saw to trim the hanging lip off.
     
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  21. big duece
    Joined: Jul 28, 2008
    Posts: 5,524

    big duece
    Member
    from kansas

    Sazall and flap disk... you might consider pining the rotors too.
     
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  22. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 828

    Jmountainjr
    ALLIANCE MEMBER

    Sounds like you could use a shop manual for basic assembly, disassembly, and tools. The original Detroit Diesel 71 series manual is good for that. Things like setting clearances sound complicated, but a few pictures will clear that up. I like printed stuff, but I have also seen free PDF downloads.
     
  23. big duece
    Joined: Jul 28, 2008
    Posts: 5,524

    big duece
    Member
    from kansas

    I was under the impression that setting one up for gas, instead of the intented use of just forcing air would call for different clearances because of heat. See if you have any scuffing on the end plates from the rotors.
     
  24. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 828

    Jmountainjr
    ALLIANCE MEMBER

    At flat head RPMs you may get away with the diesel spec clearances. The original application was on a 2200-2400 RPM engine and the blower drive ratio was 1.5 to 1.6 depending on application. So on a flat head at 10% under driven you are most likely OK. On other street applications, yes you reset the clearances. The heat generated is from the increased RPM.
     

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