Technical How is a pruned blower case mounted?

The first 2 pics are of pruned gmc case.
How is it mounted ?




Obvious how the non pruned case mounts.

 

here's one style

 

Hhmmm I have ran a lot of Blowers / Supercharger , I do not see how the 2nd post would work!!!
The second pic looks that bolts go from bottom up , (intake first ) to bottom of case,
The fist pic does not look to be that way, is the intak correct for that blower case ? Or is it just sitting there , not mounted !!
Unless the blower bolt to intake 1st then intake with blower mounts to Block /engine , Backwards BUT maybe??
It looks that rooters would over lap bolt holes on intake,

 

I believe from the inside. Locktite on the fasteners is a must.

 

I can't help with your Q',but have to comment some on the pop off's........ Kinda Funky/Kinda Cool........
I like the idea,just not the execution........But I don't know jack......... Please continue with regular programming......

 

Base of the blower case is drilled and tapped. Use studs and mouth it to a flange with the corresponding bolt pattern as show by squirrel. No bolts are inside of the blower or intake of don't correctly

 

Wow, someone had the balls to finally ask the question. I wanted to, I really did.
Mostly cuz I thought I should know what appeared to be so simple.
Pete Robinson and George Montgomery have to be the originators, best I can tell.
Had to be internally fastened, but never saw an underside photo.
Sneaky Pete was known to eliminate any unnecessary weight, I just don't understand how this could accomplish much in weight savings.
Please show some underside photos you guys, not just hypothesize.

 

And another thing, who started using the term "pruned".
Those blower cases are clearly proprietary castings, not modified GMC's.

 

the only one I've looked at in person was a 3-71 that was pruned and mounted upside down on a flathead. I didn't pay attention to how it was bolted to the intake. I did see the GM casting number on the top of the blower (they are usually on the bottom), also the holes for the oil line to the back was positioned so you could tell it was upside down.

The second photo, you can see what looks like the GM casting number on top, between the first and second ribs.

 

Some were some weren't. Can't find the article in my pile of mags but the Pete's and Ohio George cases were indeed drilled and countersunk internally to use allen screws down into intake (6 nylocs?). Rotors had to be removed but no real reason to separate anyways. Not just weight but also a lot easier to remove valve covers on an SBC with a 6-71 too.

 

Jim, any idea as to era of mfg. by GMC.
Were the (371's and 471's) oem truck app. or industrial i.e. ventilators, etc.

 

yes, they were. Lots of applications...1940s-70s. Trucks, buses, generators, marine, pumps, etc.


The 6-71 in my avatar was cast in 1961. Some of them have casting dates, some don't.

 

Found this thread from 2008 by Kevin Lee, anybody heard of him
http://www.jalopyjournal.com/forum/threads/more-coupe-progress-engine.284748/page-3
Starts on page 3, just back click to begining.

 

I have a 4-71 sitting next to the mill, waiting to be pruned.

There were several suppliers that sold them pruned. Not proprietary casings at-all.

I pondered mounting it upside-down.

 

I do believe Tom Beatty did the pruned cases back in the 50's (maybe as early as the late 40's) on the flatties & then the olds that he ran on the lakes. & also believe - but don't know for sure - that they were bolted in from the bottom through the manifold. Might've been studs instead.
Marcus...

 

GMC made one case for a ' 6 ' I think that had set's of dual ribs close together that used 3 or 4 T bolt's a side to hook up, half way up the outside of the case

Now & then you would see one on a early fueler

 

6V71
For those of us that hold the old standby 6-71 "Jimmy" in high esteem, those side bolt cases just don't cut it if for no other reason than being ugly.

 

I was thinking along those lines --- , mounting the case from the inside with rotors out.

But then I thought that it was a bunch of trouble to go thru. So maybe there's another way.

Once the thought train was rolling along-- I couldn't help to wonder that if the pruned blowers do in fact get mounted, why are the V6-71 blower cases soooo hard to mount? At least every post about a v series blower has a comment about mounting difficulty. Or crazy plates and sealing difficulties.

Seams that a V series is almost a pruned case. Yet with a big bunch more of mounting area. Compared to what's left after the removal of all this.

 

Here's some more.
I don't see the mounting

 

I dunno for sure but that chain setup is awesome in a very scary kind of way!

 

Both 1st and second pic are both of the same set up.

 

I don't see that in most of these pictures.

 

Bottom picture with the Enderle is mine (don't remember posting that anywhere did I?) Anyway yes you need to disassemble the blower to get to the bolts inside. As someone stated earlier which are countersunk. You cannot see the bolts when you look up from the bottom of the manifold. I don't think I have any pictures of it taken apart. Maybe Rob with the Gasser Passer has some, as his was bought in pieces. The drive with the yellow idler used to be my spare, and he has an aluminum manifold. Mine is all mag. I will be mocking my eng/trans into chassis this weekend if I find any other info I'll post it here.

 

If you have some pics that would be great !!

Yes those are your pics
You Posted here.

 

Either way, it's a lot of work just for a 'look'. & I rather like the unpruned-case look better, anyways. Other than the 'look', what real-world advantage is there?
Marcus...

 

So is almost everything about a rod or a custom.

Anyone can bolt on something that they took out of a box.

 

You know how when you are at the track, and a few guys are bench racing, and swapping time slips, and theres always that one guy whos car is why lighter than other guys similar cars? He was counting the ounces. I remember pics of a rear end housing Don long had hole sawed and fiberglassed over the holes...

 

I love the rocker arm covers in the 2nd pic.

 

In both instances the bolts go into the case from the bottom, either bolts are used or studs in the blower and nuts.

In the option that Paul posted the manifold is attached to the blower then mounted to the engine. the blower manifold may have threaded holes in it to facilitate the mounting of the blower then plugs screwed in after the fact. I am not thinking this up on my own I have helped assemble one that way for an old timer's blow caddy.

Jim's example is pretty straight forward. set the blower and screw it together.

Something to think about as someone is going to mention it if they already have not is that yes you loose some meat in the mounting area and no they were not running 34 PSI back then.

 

I guess if you study it deeper youll see its a "form follows function" thing. Yes it looks cool but the reasons it was done is what caught my attention. Didn't call call him sneaky Pete for nothing.