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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. DDDenny
    Joined: Feb 6, 2015
    Posts: 15,082

    DDDenny
    Member
    from oregon

    Typo I'm sure.
    10-32's would barely hold down a tin Petes Engineering firewall tag.



     
  2. Kevin Lee
    Joined: Nov 12, 2001
    Posts: 7,440

    Kevin Lee
    Super Moderator
    Staff Member

    Well damn... my half pruned case is still setting on a shelf. And the Navarro manifold is hanging on the wall.

    Glad I ran across this thread though. Looks like I need to get back to it soon.
     
    lothiandon1940 likes this.
  3. Kevin Lee
    Joined: Nov 12, 2001
    Posts: 7,440

    Kevin Lee
    Super Moderator
    Staff Member

    Well damn... my half pruned case is still setting on a shelf. And the Navarro manifold is hanging on the wall.

    Glad I ran across this thread though. Looks like I need to get back to it soon.
     
  4. PRUNNED #3.jpg I posted the picture of the side clearance to show a comparison to the picture 31Vicky with a hemi posted, I am in total agreement that it was all done for saving weight. The last time I talked about these blowers with George Montgomery he said he didn't remember exact figures but he thought he and Pete had cast up about 200 magnesium pruned 6-71 cases. Didn't remember any other numbers as far as bearing plates and manifolds. Some of the cases I've seen had Montgomery cast at the top some Pete's Eng Co. They also cast magnesium bearing plates. The one on the back of my blower only says Montgomery. I have seen others that have Montgomery and Pete's both cast in. I was outbid on this one a while back on eBay. Yes DDDenny it's a 6-71 cast in magnesium by Pete and George. Mickey Thompson was another that always had weight on the brain. He was casting parts in magnesium in the very early 60's including blower manifolds and drive parts as well as rear end carriers. Next time I see George M I'll try to remember to ask if the bores were machined while bolted down to the intake manifold. As far as the bolts, I think I read something from back in the day that George said he used 10 bolts, don't know the size. The intake my buddy Rob has had 8 holes tapped, don't remember looking at the bottom of the case at the time but his intake was aluminum and bought separate from the case which is magnesium although when I talked to him last he had located a magnesium manifold so I'll ask him again. My blower is already gone through, clearance set so I won't be taking it apart.
    Blower Plate #1.jpg Blower Plate #2.jpg
     
    loudbang and Dean Lowe like this.
  5. old round fart
    Joined: Jun 9, 2008
    Posts: 134

    old round fart
    Member
    from Norman Ok.

    Don't recall ever seeing cases horned and the bolt size as I remember were 10's. At most 12's. The manifold is thick as I remember and you only need to hold 18 lbs boost ( that is what the pop off valve was set for, and besides bigger bolts were heavy!
     
  6. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Cool stuff. I have never seen a "Montgomery" cast case before, that is a neat piece! Didn't M/T cast magnesium 3rd members for Pontiac/Olds rears at one point? I would LOVE to find one of Petes aluminum chevy 10 bolt 3rd members.
    Long story as to why I had saved the pics of the Petes Eng. case, I was looking at it last year on Racing Junk. I considered putting a blower on my daily, but making the front weight bias worse was a big concern. I was looking at mag cases for the weight savings until I did a little research regarding their sensitivity to moisture in the case seizing the rotors. In the end, I decided that adding another 100lbs to the nose of a daily driver that was already 58/42 was a non-starter, and wound up going with a cylinder head intake and cam change instead.
     
  7. nrgwizard
    Joined: Aug 18, 2006
    Posts: 1,355

    nrgwizard
    Member
    from Minn. uSA

    Well, this has gotten interesting... Thanks.
    Marcus...
     
  8. DDDenny
    Joined: Feb 6, 2015
    Posts: 15,082

    DDDenny
    Member
    from oregon

    Maybe we on different pages here, but you do realize that a #10 bolt is only 3/16" dia.
     
  9. DDDenny
    Joined: Feb 6, 2015
    Posts: 15,082

    DDDenny
    Member
    from oregon

    So, we are kinda getting somewhere (slowly), still don't have a difinitive answer about whether Pete and OGM pruned the flange off their own cases after they were cast or were they cast as-pruned.
    Falcon George submitted a photo of a Petes Engineering 671 case with the flange still in place.
    What am I missing here guys?
    1933Willys77
    Maybe you can quiz Ohio George so we can put this confusion to rest.
     
    rod1 likes this.
  10. He just had heart surgery a little while ago. Don't think i'll be talking with him anytime soon. Needs to recover and the holidays are coming. I believe he said the cases were cast pruned. Pete made more cases than the run he made with George so he might have made both types. I think it would be senseless to cast with the flange then have to go back and add an extra step to machine it off again. But like I said if I do speak with him anytime soon I'll ask. I've seen a few std type Pete's cases, the one above was just on eBay for huge money as it's a bare NOS casting. There was also a dragster at the Meltdown the last couple years that runs a flanged Pete's case.
     
  11. Here's a full side shot of the std Pete's case Pete\'s #2.jpg
     
  12. DDDenny
    Joined: Feb 6, 2015
    Posts: 15,082

    DDDenny
    Member
    from oregon

  13. Olds Pont Thompson Magnesium Carrier #2.jpg Olds Pont Thompson Magnesium Carrier #1.jpg View attachment 3064153 View attachment 3064153
     
    Last edited: Nov 23, 2015
  14. UOTE="31Vicky with a hemi, post: 11265427, member: 67302"]Any idea if that was casted by Thomson aluminum in cleveland Ohio,
    http://www.thompsoncasting.com/alloys.aspx
    One of their specialties is magnesium, done in small crucible furnaces. Good Lord you should see their pattern shop
    View attachment 3064227 [/QUOTE]

    I'm thinking Mickey Thompson would have used a foundry in California near his shop, but I don't know for sure. Maybe someone who knows Danny Thompson could find out. He might know about stuff like that.
     
  15. landseaandair
    Joined: Feb 23, 2009
    Posts: 4,472

    landseaandair
    Member
    from phoenix

    Tadaa! Car Craft, Feb. 1966.
    004.jpg 006.jpg
     
  16. DDDenny
    Joined: Feb 6, 2015
    Posts: 15,082

    DDDenny
    Member
    from oregon

  17. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Shit! I have that Car Craft, totally forgot about that article!:rolleyes::oops: The 200ish production number surprises me, I figured it would have been a lot lower than that. Looking forward to an OGM follow-up at some point. Lots of good info here.
    I was thinking there probably would have been 75 to 100ish Robinson/Montgomery cases TOTAL cast up, and the majority would have been flanged, so they would have done one set of molds and machined the flanges off. I'd never seen a "Montgomery" cast case until it was posted here. Neat stuff.
     
  18. ago
    Joined: Oct 12, 2005
    Posts: 2,199

    ago
    Member
    from pgh. pa.

    The second photo at the beginning of this thread. It looks like the blower snout is fabbed and welded. I do know today there are very few foundries casting magnesium. Maybe 3 in the US.
     
    loudbang likes this.
  19. ChassisResearchKid
    Joined: Feb 18, 2006
    Posts: 764

    ChassisResearchKid
    Member
    from Michigan

    Thanks.
     
  20. ChassisResearchKid
    Joined: Feb 18, 2006
    Posts: 764

    ChassisResearchKid
    Member
    from Michigan

    My pruned blower mounts though the intake. As in, the bolts come in from the bottom of the intake and you mount the blower and intake as one piece on the heads. The six bolts are in the same location as the injector bolts on the top. Hope this clears up some questions. .facebook_1446067446704.jpg .facebook_1446067446704.jpg .facebook_1446067446704.jpg
     
    lothiandon1940, skidmarc and y'sguy like this.
  21. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 8,839

    mgtstumpy
    Member

    [​IMG]
    6-53 on a 302W in a friends 'A' coupe. Lots of machining to make everything work and fit including angled distributor drive with crab cap. It can be done however it's not a bolt on weekend job.
     
  22. Mr48chev
    Joined: Dec 28, 2007
    Posts: 29,606

    Mr48chev
    ALLIANCE MEMBER

  23. hemihotrod66
    Joined: May 5, 2019
    Posts: 401

    hemihotrod66
    Member

    These cases look like the ones that are on the V engine diesels like 6v71"s and up....
     
  24. TRENDZ
    Joined: Oct 16, 2018
    Posts: 310

    TRENDZ

    My 2 cents... The weight benefits, and clearance benefits are secondary. Having worked around several blower cars, one of the most common failures is the gasket between the blower and intake. Real easy fix now with o rings. The superior mounting of the pruned case simply holds the gasket better. If you think about the unsupported area of a standard case/manifold, it is easy to see why gasket failure is common.
    Aftermarket performance based cases are beefed up in the sealing area for resistance to flex. A real GM 6-71 blower was never designed to have more than a few psi trying to escape between the blower/block.
     
    lothiandon1940 likes this.

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