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ZwitterND
Samba Member
Joined: September 08, 2005
Posts: 1453
Location: Fargo, ND
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 Posted: Thu May 01, 2008 5:13 pm Post subject: Zwitter manifold |
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What is the correct manifold for a zwitter? I have a VW parts book 52- 53 that lists 3 possibly 4 part numbers:
129501a -Induction
129501b - induction with intensfying jacket
129501c - from engine No. 481 713
129515 -preheating throttle ???
It is a 25 hp motor but manifold does not look like the infamous "K" manifold yet it does not look the same as the 30 / 36hp manifolds.
My engine is 1-0505568
I believe the one on there now is from a 36hp which may be causing eratic idling due to vacuum leaking.
Finally does anyone make a repro or can I modify a manifold as mentioned in a recent thread and what mod's need to be made?
Ah...the joys of owning the bastard of the splits.
Bill
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splitjunkie
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Joined: April 04, 2006
Posts: 4212
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| Posted: Thu May 01, 2008 5:43 pm Post subject: |
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This is what you should see. Notice the long preheat tube on the passenger side.
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Chris
You know, a lot of these scratches will buff right out... Jerry Seinfeld |
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johnshenry
Samba Member
Joined: September 21, 2001
Posts: 9410
Location: Northwood, NH USA
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| Posted: Thu May 01, 2008 9:19 pm Post subject: |
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I've made a few repros of those, see
this link
I make them out of 36hp intakes, mill the end castings for 25hp heads, cannibalize another 36hp intake heat riser for a "long" right leg, and increase the bend. Don't have any available at the moment, but will probably do another run of them late summer...
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John Henry
'57 Deluxe
'56 Single Cab |
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ZwitterND
Samba Member
Joined: September 08, 2005
Posts: 1453
Location: Fargo, ND
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| Posted: Thu May 01, 2008 11:07 pm Post subject: |
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Thanks guys. You do nice work John. I am curious why you canabalize a 36 manifold? Is it not possible to cut off the flange and create a new tube to the jacket? Or is this not a common size tubing? I have repaired plugged heat risers by cutting them off about 1 to 2" from the jacket then notching the end of the donor heat riser, bending the end open which allows me to weld the back of the heat riser so no exhaust leaks. This also hides the weld point behind the generator stand and requires less cosmetic surgery (aka grinding & filing). it woul be nice to weld in a new section that way. Sad part is when I bought this car in 1975 the original manifold was on it but had rusted through the heat riser. so I took it off and tossed it....
Thanks for sharing your knowledge!
Bill
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VWwerks
Samba Member
Joined: March 07, 2002
Posts: 207
Location: Wisconsin
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| Posted: Fri May 02, 2008 10:04 am Post subject: |
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| You can clean out any plugged heatriser with a torch, and/or clutch cable section chucked in a drill. A VW roto-rooter. |
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johnshenry
Samba Member
Joined: September 21, 2001
Posts: 9410
Location: Northwood, NH USA
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| Posted: Fri May 02, 2008 11:12 am Post subject: |
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| ZwitterND wrote: |
Thanks guys. You do nice work John. I am curious why you canabalize a 36 manifold? Is it not possible to cut off the flange and create a new tube to the jacket? Or is this not a common size tubing? I have repaired plugged heat risers by cutting them off about 1 to 2" from the jacket then notching the end of the donor heat riser, bending the end open which allows me to weld the back of the heat riser so no exhaust leaks. This also hides the weld point behind the generator stand and requires less cosmetic surgery (aka grinding & filing). it woul be nice to weld in a new section that way. Sad part is when I bought this car in 1975 the original manifold was on it but had rusted through the heat riser. so I took it off and tossed it....
Thanks for sharing your knowledge!
Bill |
The short reason why you can't make a zwitter intake form a single 36hp one is that the zwitter heat riser tube is just longer than the stock 36hp heat riser, and the tubing is unique, in that where it runs along the intake runner, it is "beaded". Some one here is trying to have that tubing replicated but the best source of it now for me is other 36hp intakes (who, say, have undergone their own transformations into early non-jacketed K manifolds and have had their original heatrisers removed completely...  ).
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John Henry
'57 Deluxe
'56 Single Cab |
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Matthew Tolbert
Samba Member
Joined: March 27, 2004
Posts: 707
Location: Georgia
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| Posted: Fri May 02, 2008 11:38 am Post subject: |
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John,
would this intake also be used for a May 53 oval? if so could you pm me a price for whenever you make another run of them? i could donate the 36 hp one i am using now also.
thanks
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Matthew Tolbert
1958 ragtop
1961 doublecab
1965 Notchback S |
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ProjectX
Accessory Nut
Joined: May 01, 2006
Posts: 1014
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| Posted: Fri May 02, 2008 11:50 am Post subject: |
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Matt,
My October 53 had that manifold.
Eric
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Even my nuts are plated.....
195? Project "X"
1954 Oval Convertible |
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53 0val
Samba Professor
Joined: July 03, 2003
Posts: 11396
Location: Irvine, CA
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| Posted: Fri May 02, 2008 12:20 pm Post subject: |
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Mine too.............
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"What a fool believes he sees, no wise man has the power to reason away." Dobee, Dobee, Do |
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ZwitterND
Samba Member
Joined: September 08, 2005
Posts: 1453
Location: Fargo, ND
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| Posted: Fri May 02, 2008 3:43 pm Post subject: |
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What is the differnce between these manifolds, anyone know?
129501a -Induction
129501b - induction with intensfying jacket
129501c - from engine No. 481 713
129515 -preheating throttle ???
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Bill |
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ZwitterND
Samba Member
Joined: September 08, 2005
Posts: 1453
Location: Fargo, ND
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| Posted: Fri May 02, 2008 3:46 pm Post subject: |
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John,
what do you mean by "beaded"? Are you referring to the rolled part that conforms to the intake radius?
Bill
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johnshenry
Samba Member
Joined: September 21, 2001
Posts: 9410
Location: Northwood, NH USA
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| Posted: Fri May 02, 2008 5:35 pm Post subject: |
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| ZwitterND wrote: |
John,
what do you mean by "beaded"? Are you referring to the rolled part that conforms to the intake radius?
Bill |
Yes (that is what I mean by "beaded").
The original ones have 18mm intake tubing (thin walled, like all the earlier ones...), the jacket has a "crease" running along its length front and back such that the jacket cross section would be a fat figure 8 more or less. Most of them have no logos or numbers cast, but one that I have seen does. The carb flange will be 26mm (no flare below it on the carb rider tube) and the endcastings 1.125" face with VW logos.
One made out of a 36hp intake of course has many differences, 28mm carb flange/flare, milled down 1.250" endcastings, "701E" part number jacket, no crease and the heat riser tubing is 21mm with a full 1mm wall thickness.
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John Henry
'57 Deluxe
'56 Single Cab |
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Brezelwerks
Samba Member
Joined: March 17, 2003
Posts: 1421
Location: Tyngsboro, MA
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| Posted: Fri May 02, 2008 5:51 pm Post subject: |
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| ZwitterND wrote: |
John,
what do you mean by "beaded"? Are you referring to the rolled part that conforms to the intake radius?
Bill |
Exactly. A fast way to replicate that feature into stock tubing would be by taking a solid rod that fits inside the stock intake tubing ID, then removing material from the solid rod to create a negative U shaped cavity/channel. Then re-insert the rod into the stock intake tubing, fixture up/clamp to prevent rotation of the insert. Next match the shape with a top bead roller with a flat bottom die under the stock tubing (for support), then roll it through in a few passes to slowly form the correct depth profile, then just punch out the insert and repeat. Fun project actually. I doubt even the originals were extruded stock but its possible to do it that way as well. |
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ProjectX
Accessory Nut
Joined: May 01, 2006
Posts: 1014
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| Posted: Fri May 02, 2008 9:48 pm Post subject: |
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I am very close to replicating a tube with the "beaded"  profile. This has become a tougher proposition than you might think.
I have been working closely with a tool manufacturer that is also a vintage motorcycle enthusiast. Probably the best combination to solve this problem. I should be sending some prototypes to you soon John. Everytime we are close, there are issues. The latest was thinking that you could just run a bead into some medium wall tube, it was crimped in the tool, not "beaded". Now we are doing something different 
More to come.......
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Even my nuts are plated.....
195? Project "X"
1954 Oval Convertible |
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ZwitterND
Samba Member
Joined: September 08, 2005
Posts: 1453
Location: Fargo, ND
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| Posted: Fri May 02, 2008 10:10 pm Post subject: |
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I would think you could create a forming die and press them out. Figure it would be possible with some low carbon / mild DOM tubing. I doubt that they heated them up before forming. I will have to look closer at some manifolds for forming lines. Think I found myself a project. 
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Bill |
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johnshenry
Samba Member
Joined: September 21, 2001
Posts: 9410
Location: Northwood, NH USA
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| Posted: Sat May 03, 2008 7:42 am Post subject: |
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I have a shop that is fooling with this for me now also. I with the right thickness steel, it seems that a "deep U" lower roller with a fairly wide upper roller might work. Keep in mind that the bead does not go the full length of the piece, it ends where the heat riser bends away from the intake runner. In fact there, it seems to deviate from the line of the tubing leading me to believe that in the factory, the tubing was bent first, then pressed in a jig.
I tried making a press, but it was beyond the strength of my press in my shop, and I was only practicing with 1/2 electrical conduit which is close to the OD of the original tubing. It was just to see if the press idea would work, the conduit is thin walled and seam welded and would not work well as a heat riser.
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'57 Deluxe
'56 Single Cab |
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Brezelwerks
Samba Member
Joined: March 17, 2003
Posts: 1421
Location: Tyngsboro, MA
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| Posted: Sat May 03, 2008 9:24 am Post subject: |
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| ZwitterND wrote: |
| I would think you could create a forming die and press them out. Figure it would be possible with some low carbon / mild DOM tubing. I doubt that they heated them up before forming. I will have to look closer at some manifolds for forming lines. Think I found myself a project. |
Yes no need to overthink it here, in reality there is no need for milling machines, presses, bead rollers, etc. You can keep it simple to make the bottom die (that you will insert into the new heat riser tubing) by using a $20 hand held die grinder to hand remove the U channel profile with the solid rod fixtured in a vise, and sandwich in a piece of 1/2" thick hardwood trim secured in the vise as the die bit shaft rest/follower next to the rod (just sitting a bit higher than the rod in the vise). Then just drag the rounded tip tool along the wood edge to keep your U channel nice and straight, then finish up with a round file if even necessary.
Then insert the rod into your new heat riser tubing, lay it out on a flat sturdy table, fixture it down securely. Then create the upper (so-called) "die" with a simple piece of the solid rod insert, then basically hammer the rod form in the profile you want into the empty cavity space inside, done. Read up or head to the internet to see what Ron Covell and Ron Fournier can do for example with "hammerforming". Will fill your head with ideas with valuable future ideas/skills, and its alot of fun to do actually.
Overall though, the key idea here is using the lower die as an insert, its the only real practical (and fastest way) to structurally constrain and retain the heat riser tubing in its desired shape while you are forming in the channel profile you want. Good luck, would love to see some results and the final approach used when done though!
Would probably take me 5x longer to achieve the same result using my Bridgeport Mill, Mittler beader, Pexto/Diacro press stuff here. Cool as these tools are, not worth it for something this simple unless maybe the time comes to make 200+ sections. A basic hammerform die set will produce hundreds of pieces in a fraction of the time and cost. You really want to do make this forming step fast and cheap since the real time/cost challenge is in completing the rest of the heat riser, where you will have to practice making the right bends in your trusty $99 Harborfreight Tools tubing bender that will easily do the job. So its at this next step where you will be making some landfill for awhile until you develop your own bend techniques, so its best to keep your time/cost low to start. |
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johnshenry
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Joined: September 21, 2001
Posts: 9410
Location: Northwood, NH USA
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| Posted: Sat May 03, 2008 10:43 am Post subject: |
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If you want to use the 1mm wall thickness 18mm OD steel tubing that I use to make heat risers (available from McMaster), hammerforming will never work, trust me. I have been working with this steel for 3+ years now, and it is very hard to deform axially.
Also, the simple tubing benders will not make the tight radius bend that you need as it breaks away from the intake runner. The smallest shoe you get with these benders is too big in the radius.
I formed the bends in the ones I made by increasing the bend of the 36hp donor sections (you can see in that spy cam page pics). This required careful vice/leverage bending, and torching to make the outer edge of the curve more complaint so there was no buckling. I messed up way more than I got right too.
Then added a straight section to "make up" the run to the jacket, and used anther, third elbow and flanged end for the final bend to the end.
Of course if you used some thing less than 1mm wall thickness tubing, there may be many other options. But the later (21mm OD, 36hp) tubing was 1mm and it was clear that VW finally figured out that they needed to make that tubing significantly thicker. Anything less in my book, and you'd get the chance to make another one in a few years......
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Peter_Plade
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Joined: January 09, 2005
Posts: 553
Location: Denmark
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| Posted: Sat May 03, 2008 12:09 pm Post subject: |
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I have this one for sale.
It sits on a almost NOS industrial 36hp engine.
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Brezelwerks
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Joined: March 17, 2003
Posts: 1421
Location: Tyngsboro, MA
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| Posted: Sat May 03, 2008 12:17 pm Post subject: |
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| johnshenry wrote: |
If you want to use the 1mm wall thickness 18mm OD steel tubing that I use to make heat risers (available from McMaster), hammerforming will never work, trust me. I have been working with this steel for 3+ years now, and it is very hard to deform axially.
Also, the simple tubing benders will not make the tight radius bend that you need as it breaks away from the intake runner. The smallest shoe you get with these benders is too big in the radius.
I formed the bends in the ones I made by increasing the bend of the 36hp donor sections (you can see in that spy cam page pics). This required careful vice/leverage bending, and torching to make the outer edge of the curve more complaint so there was no buckling. I messed up way more than I got right too.
Then added a straight section to "make up" the run to the jacket, and used anther, third elbow and flanged end for the final bend to the end.
Of course if you used some thing less than 1mm wall thickness tubing, there may be many other options. But the later (21mm OD, 36hp) tubing was 1mm and it was clear that VW finally figured out that they needed to make that tubing significantly thicker. Anything less in my book, and you'd get the chance to make another one in a few years...... |
Been doing true hammerforming for years here, its more of a creative process than a mechanical thought process. But not a problem making that simple profile in any thickness tubing, and I've done it more dramatically with art/sculpture with tubing much thicker no problem. Blacksmiths think this way all the time and make moving anything look easy, and it wouldn't take having to own a forge for this stuff.
The key is moving metal in smaller increments, and with enough heat if/when necessary. If your tendency is to just think mechanically than yes you would need to outsource to a supplier with a big press who would love the business I'm sure. But practically and fast, make the rod insert, heat it up if you want to loosen those steel molecules, then just slowly hammer in the profile, where it can only go with an insert/die, until its where you want it.
The leg on the heat riser is more complex I agree, again more art than science here perhaps, my Diacro bender here has some even smaller bending radii dies that will handle up to 1" diameter tubing or rod, but I'd probably just head over to my friends auto repair shop down the road to have him roll out the tight compound curve for this leg on his custom exhaust pipe bender, get it in 10-15 minutes maybe over a beer. A couple guys there make custom rod exhausts there and can tie a knot in tubing if you want it. Worth checking out as a cheap/fast option if you want a zwitter intake bad enough. |
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