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Technical How is a pruned blower case mounted?

Discussion in 'The Hokey Ass Message Board' started by 31Vicky with a hemi, Nov 19, 2015.

  1. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    True enough, and I DO like the look......but I can't help but think the structural integrity of the case is compromised in the event of a backfire. I know, I know, that's why blow off plates are usually/always incorporated. Hopefully, should a backfire occur, the blow valve is sufficient to relieve enough pressure to save the blower. The custom case mods have to be time consuming to perform and assemble as well.

    It does present a nice appearance.......... :)

    Ray
     
    Last edited: Nov 20, 2015
    porknbeaner likes this.
  2. akoutlaw
    Joined: May 13, 2010
    Posts: 1,258

    akoutlaw
    Member

    Get a copy of George McNicholl's book " How to build Ford Flathead V-8 Horsepower" He writes from a machine shop in Vancouver B.C. It is owned by Luke Balogh. Refer to chapter 26 pages 151 thru156. It has some pictures of Mr. Balogh doing this. The blower is mounted with studs drilled & taped to the bottom of the blower & mounted thru holes in a flange around the top side of the intake manifold. He is doing this on a Ardun conversion, but the process would be the same for most motors using a "pruned" blower. Hope this helps. Bill
     
  3. I'm not sure on all of the progression of events and changes what happened first and why, but blower restraints and shear bolts are the norm now
     
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  4. Katuna
    Joined: Feb 25, 2005
    Posts: 1,822

    Katuna
    Member
    from Clovis,Ca.

    First and second pics are both of the Hollish Bros Miscalculation 3, the most bitchinest Comp Coupe ever.
     
    ChassisResearchKid likes this.
  5. DDDenny
    Joined: Feb 6, 2015
    Posts: 19,144

    DDDenny
    Member
    from oregon

    I guess I can see doing that on Cammers as Pete and George did, and Hemi's, just don't see why sbc's would have needed it.

    Ok, I'm only 61, and the heyday of this "pruning" thing is apparently before my time, but the only "flangeless" blower cases from the early 60's that I recall seeing are the 671's that Pete and George were using, and I've read that they were both involved in the casting and machining of these cases.
    I still can't believe that the sole reason was for weight savings. My thinking is they must have been looking for more output (input), or making a stronger case, or both. I'm also pretty sure it wasn't an availability issue yet.
    Here's where I'm a bit confused; they say some cases were "pruned" and some weren't.
    I've "pruned" only one case, and that was a 671's with the Oem lip that was built in for easier installation on the original deisel engines.
    It's easy to hide any of the modifications when a case is polished, it's those "as-cast" looking early GMC 371'S and 471's that are flangeless and flipped that I have never seen.






     
  6. QUOTE="31Vicky with a hemi, post: 11260657, member: 67302"]If you have some pics that would be great !!




    Yes those are your pics
    You Posted here.[/QUOTE]


    Ha, that's what happens when you get old. You need someone to tell you things you've done in the not so distant past. Now I remember that post.
     
  7. Louie
    Joined: Mar 3, 2001
    Posts: 670

    Louie
    Member
    from NJ

  8. wrenchbender
    Joined: Sep 5, 2007
    Posts: 2,337

    wrenchbender
    Member

    31 Vicky the flatcad with the 4-71 and 4 carbs is mine and it has been drilled and tapped on the bottom with studs installed the intake I run is the one squirrel posted the pattern is the same as the top of a 4-71 with the two center ones added I had a friend Trim the blower with a Bridgeport mill I still have some finish work to do to finish it up I had a sneaky Pete 6-71 case at one time it was an aftermarket case made of magnesium I have seen a couple over the years and all of them had counterbored holes and used Allen cap screws to hold it to the intake from the inside and yes if blower needed to be removed it had to be disassembled I real pain in the ass in my opinion especially for a sbc but I must admit it is damn kool looking
     
  9. If you knew Pete Robinson, you'd know he would spend days in his shop to cut a pound off one of his dragsters. His blown SBC not only ran "pruned blowers", but Pete went so far as to cast his own blower cases in magnesium. I believe the pruned mag case saved him about 5 lbs. And thinking like that is how you get a top gas car that weighs under 990 lbs! I occurs to me that Pete and Ohio George were friends, and both ran Pete's mag cases. Since both were top notch machinists, I'll go out on a limb, and say they probably line bored the case already torqued to the manifold. Think about it.
     
  10. landseaandair
    Joined: Feb 23, 2009
    Posts: 4,485

    landseaandair
    Member
    from phoenix

     
  11. You are correct the manifold is a copy of a WEIAND with the mounting bosses machined off and mine is cast in magnesium and my pop-off plate is also mag with the jet star "say why and" logo
     
  12. Nice, is that for a Cadillac Louie?
     
  13. nrgwizard
    Joined: Aug 18, 2006
    Posts: 2,516

    nrgwizard
    Member
    from Minn. uSA

    Guess I sorta stuck my foot in my mouth, unintentionally.

    Kinda short-cut my statement. I should've added, "if my understanding of mounting isn't correct (which I thought I'd seen pics of eons ago), & in fact the blower does bolt on from the inside, requiring that it be disassembled to do so, then go through the proper set-up each time, then it's a lot of work for a 'look'. & since we're talking racing - lakes, drag, etc, not street-rodding, what real-world advantage is there.

    I understand going through all kinds of shenanagins to obtain a 'look', & all sorts of machinations to decrease every ounce for top-level racing. Esp when someone can afford spares already set-up for a quick swap. Not to mention 'trick', both for its' own sake - to wow the mouth-breathers - , & for gain an advantage for racing. But I'm not seeing the two crossing paths very well. Time, trouble & un-needed complexity don't seem to mix too well in most racing.

    One of my favorite racers was Sneaky Pete - due to his engineering, & almost fanatical weight-cutting.Esp when he had the Cammer. Didn't know him, or any other 'names'. Doesn't mean I don't know about & admire them.

    I still rather like the look of the 6-71 unpruned. Esp in Mag. That's just me. I don't hate the pruned case, but still... :) .
    Thanks for the thoughts.
    Marcus...
     
    stillrunners likes this.
  14. When you look at this, its easy to see the benefits of pruning, especially if there's the slightest need for raised or modified valve covers. Running a solid lifter cam.

    image.jpg
    So prune the manifold, prune the case.
    Attach them together ( which was the mystery) and it becomes more or less 1 piece. I don't think a guy would swap or remove a blower only on the car, that would be bench work. The rotor housing and manifold would be joined into 1 piece more or less because of the Inaccessible fasteners.

    Kind of like this thing, where the rotor housing is more than part of the manifold, they are now one in the same.
    image.jpg
     
    belair likes this.
  15. DDDenny
    Joined: Feb 6, 2015
    Posts: 19,144

    DDDenny
    Member
    from oregon

    Vicky
    Yep, it's close on a sbc, just don't see how that would be all that hard to deal with, considering what's involved with removing a pruned case from an (any) engine.
    I still firmly believe that what wer'e (me) missing is hearing from someone from the pertinent time period to fill in the blanks as to the virtues of a "pruned" blower.
    It is obvious to me that the bulk of fuel and gas dragsters of the early 60's era used conventional blower (671) cases and intakes without issues, even as valve covers evolved and spacers came on the scene.
     
  16. Yes there's a little more side clearance with a pruned case 1448230502617.jpg
     
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  17. DDDenny
    Joined: Feb 6, 2015
    Posts: 19,144

    DDDenny
    Member
    from oregon

    Willys
    I can't tell by your photo, is that a 471 or 671 blower?
    And, I still gotta ask, these sbc intakes for the "pruned" style blowers, they came out before the sbc competition 671 intakes correct, were they still being used in competition after the next generation of intakes came out?
    The other question that has not been clearly answered is; blower cases that look like
    the one in your photo, did they come cast from GMC like that or have they all been so cleanly finished that they just look oem. I ask only because some photos I've seen look like they are pruned but still have the rough, textured finish on the ribs.
    Yours appears to have been polished then painted, am I correct in this.
     
  18. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    You guys really think a guy who would go to the trouble to cast an aluminum carrier for the early chevy 10 bolts, and a mag steering box was pruning these cases for valve cover clearance? You guys are overthinking this...
    ScanImage0012.jpg
     
  19. DDDenny
    Joined: Feb 6, 2015
    Posts: 19,144

    DDDenny
    Member
    from oregon

    Wasn't me judge.
     
  20. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    what Dean says is dead-on. Pete Robinson was absolutely fanatical about weight savings. Theres nothing more complicated behind the pruned cases than that. Don Long was another one. Remember, Pete first came to fame for winning top eliminator at the '61 US Nats against a field of twins and stroked Chryslers and Oldsmobiles with a moly Dragmaster chassis with a chevy 10 bolt rear and a sbc.
    later on OGM and Pete both ran mag cases, and pruned those too! Now that's really getting obsessive...
     
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  21. DDDenny
    Joined: Feb 6, 2015
    Posts: 19,144

    DDDenny
    Member
    from oregon

    Wrong-o-red-rider
    I've always been under the assumption that OGM and Pete cast and machined their own cases.
    They may have used a "pruned" aluminum GMC case as a "pattern" for the later ones.
    Disclaimer as to the facts, I wasn't there to witness any of this.
    George, you are much better at sleuthing out this stuff than I am, so, your mission if you decide to accept it; is to get to the bottom of this.
     
  22. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    This is an easy one.:D
    case1.jpg
    Petes mag case, cast with the flange in place.
    oGeorgeMontgomeryMalcoGasser24-vi.jpg
    OGM mustang, mag Petes case with the flange pruned. Probably machined the flange off first, then Dow 7.
    I had these pics saved on my computer, didn't even have to dig them up. I assume Pete cast the case with the flange to make them easier to sell to other racers.
     
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  23. DDDenny
    Joined: Feb 6, 2015
    Posts: 19,144

    DDDenny
    Member
    from oregon

    George and Vicky
    Three things:
    1. I hate it when I'm wrong.
    2. I knew George could prove me wrong if I was.
    3. Gotta thank @31Vicky with a hemi for opening the door on this.
    Good stuff guys, I like getting the facts, not just your typical internet hypothesizing.
    This is the reason we all like this place so much.
     
    loudbang likes this.
  24. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Honestly I just am FUCKING OBSESSED with the minutia of drag racing and hot rodding history. I'm a sick puppy, what can I say. I don't mind being wrong at all, if I learn something to stash away in my twisted, demented little brain. You and I have some good ones, the WCM boat header stuff was fun too.
    I love having conversations like this, don't care much if I'm right or wrong, its the process and digging up the photos that's fun. One of these times when I am down south, we gotta meet up, I'd love to talk with you about some of the NW history you have witnessed. Still looking for that proof sheet with the stick Plymouth.
    And 31vicky and I pm a LOT behind the scenes too, mostly about some of the "tech" threads...;)
     
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  25. old round fart
    Joined: Jun 9, 2008
    Posts: 134

    old round fart
    Member
    from Norman Ok.

    I raced with Pete for a year before his death and a street driven t bucket with a pruned blower he set up for me. It was bolted down with 6 no. 10x32 Allen bolts from inside the case. I drove it from Atlanta to Memphis for the 2 nd Street Rod Nationals. I will say he was the most influential person I ever knew and I miss him to this day.
     
  26. old round fart
    Joined: Jun 9, 2008
    Posts: 134

    old round fart
    Member
    from Norman Ok.

    Thinking about Pete I remember coming in the shop one day bad he had a mag valve cover in the mill "removing thickness". His mag steering had aluminum gears and he used helium in his tires. Yes he was anal about weight.
     
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  27. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Do you recall if Pete finish honed the blower case after it was bolted to the manifold like Dean says? I'm very curious about this.
     
  28. Yes me too,
    Also 6 - #10x32 screws doesn't seem like enough to hold it down
     
  29. landseaandair
    Joined: Feb 23, 2009
    Posts: 4,485

    landseaandair
    Member
    from phoenix

    Sorry, think I started that, just saw it as an added benefit. I know he also preferred 2" pulleys to shave a bit more weight.
     
  30. landseaandair
    Joined: Feb 23, 2009
    Posts: 4,485

    landseaandair
    Member
    from phoenix

    x2, probably more like 3/8". Wish I could find that damn article.
     

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