Ed,
I had brazed my fittings with the aluminum brazing rod, but when I ran the
engine and built up pressure on the system, one broke off on one side.  I
decided after that to have them welded, so I took a chisel and rapped on

bungs.  They popped off pretty easy.  The brazing rod melts easily enough,
but it just doesn't seem to grip real well to the cores.  I heated mine

a MAP gas torch, and had them pretty hot when I brazed them.

I took them to the same place that welded my intake for me, and he TIG
welded them with no trouble at all.  Of course this welder has been doing

for 30 years, and welds all sorts of materials.  I have much better peace

mind with those bungs welded, and not having to worry about one popping

while up flying.

Regards,
Steve Brooks


 -----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]  On
Behalf Of Ed Anderson
Sent: Tuesday, September 07, 2004 6:30 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Photos of Core tanks internals

David, I'll check on the thickness of the end plates (I believe that is

you ask for the thickness on).  But from recollection, its a bit more than
1/8".  Regarding welding, actually some of the newer aluminum brazing rods
would probably work better.  I finally found a radiator shop who repaired
radiators and they simply brazed the fittings on.  But, clearly Rusty and
others had better luck than I did with the welding approach.

Ed

Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
From: "David Carter" <dcarter@datarecall.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, September 07, 2004 4:25 PM
Subject: [FlyRotary] Re: Photos of Core tanks internals


> Ed, great pictures and info!!  Thanks a lot.
>
> The larger tube on my cores is exactly 3/4" OD.  The end seems to have a
> 1/2" long insert in it - insert has OD of 0.678, which is the ID of the
3/4"
> main tube.  If I cut off that 1/2" "tip" of the larger 3/4" OD tube to
> eliminate the "insert" (which has a smaller ID of 0.565), then I'll have

> tube with 3/4" OD and .678 ID.
>
> On the other end cap the tubing is exactly 1/2" OD and about .460 ID -

> has the little filter inside.
>
> I plan to run my 2 evap cores in parallel - to get greater flow than

> be possible running them in series.
>     -  I will use two home-made splitter blocks, each to have a standard
> radiator hose on one side (attached to engine "hot" outlet or water

> respectively) and two smaller 3/4" ID hoses on the other side (to attach
to
> evap cores, inlet or outlet, respectively).
>
> After I modify each core to replace the 1/2" OD tubing with 3/4" OD, so
each
> core has a 3/4" ID inlet and a 3/4" ID outlet, these inlets and outlets
will
> have an inner area of 0.361 sq inches.
>     -   With two cores, I'll have a combined inlet area (and outlet

of
> 2 times that, or .722 sq inches, to be "fed" by a single automotive
radiator
> hose via the 2 splitters.
>     -  Given "required area" of .722 (minimum), the "main single hoses"
and
> any associated fittings must have at least .722 sq inch area which

> to an ID of 0.9588 inches (or more - use of "stock" hose and fittings
sizes
> may result in "next size bigger" than 1" ID).
>     -  Looking at just one website for hoses & fittings, a fitting for

ID
> hose had an inner bore ID of 0.84 inches.  To get a fitting bore ID of
> approximately 1" requires going to a 1 1/4" ID hose.
>
>     -  What is the standard sized water hose used on an RX-7?  1 1/4"? 1
> 1/2"?
> . . . . . -- I'll  use whatever fits the stock pump and a stock

> and run it to my home-made "splitter" blocks.
>
>     -  Coming out of the splitter block to my 3/4" OD "inlet" tube on

> core, I'll use smaller "heater hose" of 3/4" ID to slip over 3/4"OD

on
> cores.  I'll select the tubing coming out of/going into my 2 splitter
blocks
> to be identical to that 3/4" OD tubing on the cores.
>
>     -  Using water hose instead of AN fittings, where do I look/go to

> "bungs" on  3/4" OD tubes and 1 1/4" ID hose bungs?  I'd want to use 2
water
> hose clamps to hold hoses securely.  I haven't found a good website or
> source for the "bungs" to weld onto the evap cores. (I'll be putting
orange
> "fire sleeve" on all hoses - and wiring? - in the engine compartment.)
>
> In case I wanted to get even more flow than the 3/4 inch OD tubing on

> evap cores would allow, is there room in those little flat spots on the
end
> caps to weld on a fitting or tubing with 1" OD (with approx ID of 0.964
> inches or so if wall thickness is 0.036 + or -)?
>     -  I held my core in my lap with an "end cap" on each side, the 13
> coolant tubes running horizontally left & right; I laid my ruler on the
core
> and measured 1" or maybe 1 1/8" from "inside" side of "end cap" to the
> narrow (wasp waist) of the segments of the end cap.
> . . . . - - Ed, I just reviewed your web 1998 web document on how many
cores
> you went thru before you found a good welder and how the low temp alloy

> the cores would melt when using the higher temps required to weld on the
fat
> fittings.
> . . . .  ---- Looks like going to a "max size fitting" of 1" or so might
get
> the welding heat too close to the seams and not be worth the risk of
ruining
> the core.  I'm thinking I'll stick with 3/4" OD tubing on the cores.

> wondered if you could measure one of those "sample cores" to get the
> dimension "perpendicular" to the nominal 3" thickness of the end caps

> is available for welding.
>
> David
>
> ----- Original Message -----
> From: "Ed Anderson" <eanderson@carolina.rr.com>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Tuesday, September 07, 2004 11:38 AM
> Subject: [FlyRotary] Photos of Core tanks internals
>
>
> > Well, David,  I just went down to the shop through the pouring

of
> > Frances and cut open each side tank of a core I had taken from the
> junkyard
> > years ago.
> >
> > The photos are attached and speak for themselves - no dividers or

> > impediments to coolant flow in the tanks - pretty clean channel from

> to
> > bottom.  Each "row" has 5 approx 1/8" (perhaps slightly larger) dia
holes
> > that conduct the water through the core to the opposite side tank.  So
14
> > rows * 5 * area of 1/8-3/16" dia hole would give a cross flow channel
area
> > of around 0.86 sq inches to 1.93 sq inches - probably toward the

> > figure.
> >
> > So as Bill suggested they may have redesigned the heat exchangers to
take
> a
> > different approach to recondensing the refrigerant calling for the
divider
> > plate.  Given the relatively small cross channels, it is my opinion

a
> > serpentine cooler is probably offering considerably more resistance to
> flow.
> > Some of the radiator shop webpages give an estimate of the increase in
> flow
> > resistance of a Serpentine core over the straight through - as best I
> recall
> > it was something like 4 times as best I recall.
> >
> > So, its clear that not all GM evaporator cores are created the same

> > This one was from the an late 80s early 90s Cadillac.  I looked all

> for
> > some identifying model number but could not find anything.  I do

it
> > had a yellow sticker with a black C on it when I yanked it.
> >
> > In any case, it looks like we can not simply order just any GM cooler
> core.
> > I suspect that when they switched over to the more environmental
friendly
> > refrigerant then  there could have been some redesign of the core, but
> just
> > speculation on my part.
> >
> > Here's the photos
> >
> > Ed.
> >
> >
> > Ed Anderson
> > RV-6A N494BW Rotary Powered
> > Matthews, NC
> > ----- Original Message -----
> > From: "David Carter" <dcarter@datarecall.net>
> > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > Sent: Tuesday, September 07, 2004 11:55 AM
> > Subject: [FlyRotary] Re: Water pump problem
> >
> >
> > > Thanks, Ed.
> > >
> > > I wonder Steve Brooks's core with a "plate" is different from the
> > > GM/Harrison cores that I have (Chev'y Caprice).
> > >     - When I probed my core last night and found no plates in the

> cap
> > > with the larger of the two welded tubes, I DIDN'T check the other
side -
> > > those smaller 1/2" OD tubes turn 90 degrees and run about a foot, so

> > never
> > > probed that side.  That is the side that has the little "filter"
and/or
> > > "expansion jet" thing sitting about an inch down inside.  Perhaps
> there's
> > a
> > > plate on that side that matches what has been discussed recently.
> > >
> > > If Steve's core is a typical GM/Harrison core, then I'd like to
> understand
> > > more about which end "the plate" is in and tell us more about "the
tube
> > that
> > > was removed".  I've not yet cut into any of my cores to mod the
> fittings,
> > so
> > > am ignorant of the insides.
> > >
> > > David
> > >
> > > ----- Original Message -----
> > > From: "Ed Anderson" <eanderson@carolina.rr.com>
> > > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > > Sent: Tuesday, September 07, 2004 6:54 AM
> > > Subject: [FlyRotary] Re: Water pump problem
> > >
> > >
> > > > Hey, David, not to worry.  We have all hit the "Send" button on an

> > mail
> > > or
> > > > two and later wondered why we did. {:>)
> > > >
> > > > Ed
> > > >
> > > > Ed Anderson
> > > > RV-6A N494BW Rotary Powered
> > > > Matthews, NC
> > >
> > >
> > >
> > > >>  Homepage:  http://www.flyrotary.com/
> > > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> > >
> >
>
>

--------------------------------------------------------------------------
--
> ----
>
>
> > >>  Homepage:  http://www.flyrotary.com/
> > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >
>
>
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html



>>  Homepage:  http://www.flyrotary.com/
>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html


>>  Homepage:  http://www.flyrotary.com/
>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html