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Hot Rods 4/71 blower rebuild

Discussion in 'The Hokey Ass Message Board' started by Desoto291Hemi, Sep 28, 2019.

  1. Hi Guys,
    I thought I would post a few pics of my blower rebuild.
    Nothing fancy really,,,,but I wanted to show what can be done at home with a little time and some patience.

    First,,,the core. It was not too pretty,,,but ,,,when inspection and a closer look was completed,,,,all in all not bad to start with.
    I will post more soon.


    Attached Files:

    Chucky, Stueeee, loudbang and 2 others like this.
  2. Now,,,the rotors.
    They looked awful,,,covered with kind of a green corrosion.
    After I washed them in a sink of hot water and Dawn liquid,,,,and used a Scotchbrite pad,,a 6x9 green pad,,,,they really turned out nice.
    About 30 minutes or so of cleaning,,and they look great!


    Attached Files:

    Last edited: Sep 28, 2019
    402BOSSMAN, loudbang, Deuces and 2 others like this.
  3. The bearing plates were not in bad condition.
    Almost completely free of any marks or scratches.
    I just did a heavy duty cleaning,,,,used a scotchbrite pad on a 90 degree sander to get them ready to polish,,,and then about 20 minutes combined to polish them on my pedestal grinder/polisher.
    Before and after pics.
    I think they turned out pretty good.


    Attached Files:

  4. I have the case just about ready to go.
    Here are some pics earlier when I was finishing up polishing and trying to get ready to paint.
    I only polished the ribs and the end plate areas,,,,the case had a few external defects,,,but it turned out ok,,all in all.

    Attached Files:

    Last edited: Sep 28, 2019
    loudbang and kidcampbell71 like this.
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  5. Now,,,,I just got the case done a little while ago and got the tape off where I painted the outside.
    I am really excited about how it turned out,,,not too bad,,,for a beginner.
    I will post some more info about setting the clearance and all that later.
    Hope you guys like it and decide to try this as well.
    Not all that bad really.


    Attached Files:

  6. 41rodderz
    Joined: Sep 27, 2010
    Posts: 3,320

    from Oregon

    I like it and your hands on hot rodder attitude.:cool:
  7. To paint the case I used Hammered black by Krylon
    It seems to work ok.
    I will see when it dries a little more,,,it applied very well.
    Krylon fusion all in one,,,,I had never seen it before,,,thought,,,what the heck!
    It $4.95,,,,at Walmart.


    Attached Files:

    loudbang, OFT and kidcampbell71 like this.
  8. Thanks 41,,,I really appreciate that.
    If more people will try something,,,the more we all learn.

    loudbang and kidcampbell71 like this.
  9. Budget36
    Joined: Nov 29, 2014
    Posts: 2,594


    That's going to look nice.

    What are you putting it on, and what's it going into?
    loudbang likes this.
  10. Oh yeah,
    I had already set the clearance and timed the rotors earlier this week.
    Then disassembled to finish the rest of the hard part,,,(the pretty!!!)

    It has about 8 thousandths on the rotor to front bearing plate.
    About 12 thousandths rotor to rear plate.
    Between 6 and 7 rotor to rotor.
    And 4 at the bottom of the case to rotor.
    I was really concerned about all of this,,,but it is not nearly as hard as it appears when reading what to do..
    Soon,,,,I will do the final assembly.

    loudbang and kidcampbell71 like this.
  11. I am getting it ready for my 291 Desoto,,,,at least that is the plan right now.
    My plans are to put together and use a 4 speed tranny(A833),,and an 8 3/4 rear diff.
    The body I plan on using is a California kid,,,34. 3 window.
    It won’t be just like it though,,,,I will probably just use the body part itself,,,and go my own direction after that.
    Pete really had a beautiful car there,,,I could never even get close to it!

    Last edited: Sep 28, 2019
    loudbang likes this.
  12. Mike Colemire
    Joined: May 18, 2013
    Posts: 1,086

    Mike Colemire

    Are the 4-71's easy to come by and what are they used on?
    loudbang likes this.
  13. big duece
    Joined: Jul 28, 2008
    Posts: 5,708

    big duece
    from kansas

    Make sure you put the same shims in their original places under the front gears. The rotors will grow in length depending on the heat generated. You might check with someone that does this for a living on end clearances.
    loudbang likes this.
  14. OFT
    Joined: Jun 1, 2005
    Posts: 508


    Looking good! thanks for sharing build.
    4/71's easy to find in your area? Like looking for hen's teeth in NE Idaho(as are older car's/parts).
    loudbang likes this.
  15. Already checked and got the clearance low down.
    I got lucky and didn’t have to machine anything.
    It is a tad loose,,,clearance wise,,,but very usable
    If it had been tight,,,then ,,,,,it is machine work time.
    Since it is a street application,,,loose is just fine.
    That is why you want more clearance on the back plate,,,,the rotors will grow longer that direction.
    There is information on these things everywhere .
    About the availability of them,,,they are around,,,,just try to keep looking.

    loudbang and kidcampbell71 like this.
  16. They were used on a lot of applications back in the day.
    The 3/71 were used on inline 3 cylinder engines,,,the 4/71 on inline 4 cylinder engines,,and so on.
    It means it was designed for an engine with 3 cylinders,,or 4 cylinders,,,or 6 cylinders,,,,producing 71 cubic inches of displacement per cylinder.
    Old GMC,,,old Detroit,,,,a lot of old trucks and equipment had them.
    I remember when I was a kid,,,old trucks that put oil,,,tar down on the country roads,,used them. A lot of old equipment,,,and pumps,,,used them.
    Keep looking,,they are out there.

  17. Here are a few extra pics with the bearing plates hung on by the setup screw.
    Not bad really,,,I know it is not show quality,,,but that was not the objective.
    I want to show that it can be done at home and on a limited budget,,,with basic hand tools.
    At least that was what the old guys did.

    I wish I had took some pics of my work removing the case lip,,,,I will do that on the next one and post the pics on this thread.
    It was really easy,,,and turned out great,,,,almost like from a Bridgeport,,,super easy!


    Attached Files:

    Hotrodmyk, Budget36, dmdeaton and 4 others like this.
  18. dmdeaton
    Joined: Nov 25, 2017
    Posts: 366


    who makes the pulley setups for V belts, and what are you going to use on this?
    loudbang likes this.
  19. I’m not sure about the vee belt setup,,,,I have seen them several times though.

    I plan on going with the 1/2 inch pitch belt,,,3 inches wide.
    The reason being,,,it will be more than adequate with the boost I plan to run.
    Half inch works very well until you get a lot of boost,,and then the belt will start to ratchet on the pulley,,(,skip a tooth,).
    Then you want to think about 8 MM drive,,or even 14MM,,,whatever you like best.
    I only plan on about 6 to 8 pounds of boost,,,probably closer to 6.

    Another reason why go 1/2 inch pitch is ,,,the belts and pulleys are priced more economical.
    Also,,,I happen to already have a belt and pulley from another time.
    I just need one more pulley,,,,The pulleys are the worst part,,,a little pricey.

    loudbang likes this.
  20. big duece
    Joined: Jul 28, 2008
    Posts: 5,708

    big duece
    from kansas

    For the 471, a 3" bottom pulley and 2" idler and 2" top pulley would look good. You can still get 2" belts.
    loudbang and Desoto291Hemi like this.
  21. Here is some pics that I meant to post.
    It is the cup plugs for the plates to keep all the oil in the housing.
    Not absolutely necessary,,,but it keeps it from being a mess if you pull the blower off the manifold later,,,it keeps all the oil up in the housing area.
    The cup plug are Dorman 555-008.
    They work very well,,,,and go in easier if you have a arbor press.
    My press is a cheap one from Harbor Freight,,,but works very easy.

    Just use a small socket that fits inside,,,and no problem at all.


    Attached Files:

    Deuces, 402BOSSMAN, loudbang and 2 others like this.
  22. I might still use a smaller belt and pulley,,,,I can always cut my one pulley down to 2 inches if needed.
    Still in the fabrication stage!

    loudbang likes this.
  23. By the way,,,here are some pics of a bad bearing plate I had to replace.
    The bearing journal had cracked up through the bolt hole in the boss.
    Always look for this,,,if you are working on an old one someday
    The material is very thin here and it will usually crack in the bolt area because there is hardly any aluminum there to support it.
    It could still be repaired with a steel collar to go around it,,,,I have some like that as well.
    As it turned out,,,I had one that is almost .125 thicker in this area around the boss.
    I guess they must have upgraded their casting as time went by,,,,because of failures in the field?
    Anyway,,,I will use it for mock-up purposes,,,,not to be used.


    Attached Files:

    Deuces and loudbang like this.
  24. big duece
    Joined: Jul 28, 2008
    Posts: 5,708

    big duece
    from kansas

    I have a front cover that accepts modern snout if you need one 20191003_210405.jpeg

    Sent from my SM-G900P using The H.A.M.B. mobile app
    Deuces and loudbang like this.
  25. Hey guys,
    Is there any specific location for the vent on the front cover.
    Any areas better than others ?
    I was planning on putting it on the top side,,,directly above the tri cover plate area.
    Or should I install it on the front face of the cover to the top left of the tri plate.
    I have seen these both ways,,,,just curious if one is more effective than the other?

    Deuces and loudbang like this.
  26. Fordors
    Joined: Sep 22, 2016
    Posts: 2,300


    There is an interesting train of thought on pressure relief valves that says it is not wise to let the air out.
    Boost pushes past the seals and in turn it then puts back pressure against the seals increasing their effectiveness.
    Where the rub comes in is that the boost was not only carrying air but also gasoline. Every time you release that air you let more return with more gas, eventually diluting the gear lube.

    Fact or fiction? I don’t know, but I do know Dyer recommended 90 wt. gear lube to me and that would be hard to dilute. BITD some guys used castor oil in the gear case, the reasoning was if it somehow got into the engine it would not contribute to detonation. Some guys might use 30 wt. motor oil, or whatever else they chose.
    BTW, in answer to your question I put my relief valve on top, but I doubt it really matters.
    Deuces and loudbang like this.
  27. Thanks for your post.
    I think it looks better on the top.

    Now that you mention it,,,
    I have an old Dyer street charger drive that I plan on using on a future build.
    You are correct,,,,it does not have a vent.
    It has a Allen plug on top,,,and a plug on the face that I assume is a hole for the fill level.

    And yes,,,,I plan on using 90 wt in the front.
    I think it will help the gears be quieter and make the bearings and seals last longer.
    This might be overkill,,,,but I don’t see any reason not to use it.

    Deuces and loudbang like this.
  28. Here is another update on my progress.
    I got my gaskets in,,,,and my bolts and washers.
    I went with stainless hex head bolts and stainless washers.
    Stainless will not seize in aluminum,,,right?
    Should I have put any loc tite on them,,,I still can if need be?
    They are not shiny,,,but I didn’t need all that.
    I got my gears torqued,,,and finished the front cover.
    I use an aluminum piece to wedge between the gears to hold them during the torque sequence. I have never felt comfortable seeing a hammer handle wedged into the rotors to do this. Just me I guess?

    BTW,,,,,I did put a hole for a pressure relief valve,,,it was already ordered anyway.
    It is up on the left front ,,,around 10 o’clock .

    I still have a little more to do,,,I have to finish my rear plate,,,then it should be ready to go.


    Attached Files:

    Deuces, loudbang, akoutlaw and 6 others like this.
  29. Deuces
    Joined: Nov 3, 2009
    Posts: 17,940

    from Michigan

    That 4:71 is looking cool!.... :cool:
    lothiandon1940 likes this.
  30. Thank you Deuces,
    It is turning out very nicely,,,,I am kind of proud of the job I have done.
    I am not bragging,,,,I just wanted to show that things like this can be done if given the encouragement.
    Our young people,,,and even our older ones,,,(my category),,have ideas about doing projects like this. They just need some examples of things to try.
    Then that produces other ideas,,,,and more ideas,,,and so on.
    If I can encourage someone to step up and try something new,,,,then that person will cause someone else to do the same.
    Maybe not a supercharger project,,,but maybe try a carb mod,,,a transmission rebuild,,,or modify an engine in a different way.
    My forte is drivelines,,,,engines,,trans,,,,rear differential,,,but I pick up ideas from all people I meet.
    Someday I would like to try some frame and body mods on a future project.
    I have no talent for that,,,,I see guys on here that cut,,modify,,,chop,,,and completely redo a chassis,,,,it amazes me,,,,now that is talent in my book!

    But,,,,,they inspire me,,,,and someday I will have the resources to do that.

    Deuces, OFT and kidcampbell71 like this.

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