Making of: intake manifolds

Welt · Posted: Mon Feb 03, 2014 2:08 pm Post subject: Making of: intake manifolds

Thought I'd make a separate thread for these "home-made" manifolds here at the Vintage Speed forum rather than continue posting this stuff in my oval-thread. I guess this is the place where the lone few nutjobs are that might be interested in what I'm doing. Some of this is old stuff but I have some new pics and progress as well. Prepare yourself for a long post and maybe you'll learn something about casting too!

All this began when I needed to design and make some castings of my own as a part of my degree in foundry engineering. The castings needed be simple enough to keep pattern/core costs at a reasonable level. What a great opportunity to make something that relates to aircooled VWs. Making something for DP engines and newer models in general was not sensible IMO as almost anything one can think of is made and sold with the cheapasses in mind. Having a 50's car directed my choice to 28 PCI manifolds. All the available manifolds in the 36hp market seemed to be either very rare or ludicrously priced!

I started taking measurements for the manifolds from a spare 36hp engine I had laying around. After that came the design phase:

Image may have been reduced in size. Click image to view fullscreen.

Wanted to make the middle section curved and not straight as some designs are. More about form over function as with the whole VS scene. It would be stupid and wasteful to make two moulds for a single pair of manifolds so my design was a pair per casting.

Ran some simulations to get expected results. Thicker flanges connected to thin sections will have some inevitable porosity without added feeders (reserve material for shrinking). Parts this size won't easily have big defects so the results were a non-issue anyhow. The next thing was to design and make the patterns.

Here's the finished core box and pattern halves.

Then came the fun part, actual casting. Assembling a mould:

Melting some aluminium and pouring it.

Raw castings.

Got a few samples machined and it was time to see if everything fit as they should. Yes, they did! Bought some phenolic spacers off the classifieds to complete the set. Both good 28's I had were equipped with smooth fuel fittings and plugged vacuum so it was time to get a little creative. Not the final design by any means.

At first I was content with the as-cast finish on these but tried polishing a set. I was sold, polished is the way to go. Here's a few after a quick polish:

The fit seems to be great, Präzision!

Haven't had the time to make a complete linkage yet as everything else seems to suck up all the available time but slowly I'll get there. Also slowly finishing a small stock of polished ones. Tune in for more at a later date.
_________________
1956 Oval
1971 Type 181
1974 Baywindow
1974 Beetle

Kjell Roar · Posted: Mon Feb 03, 2014 2:18 pm Post subject:

Looks wery nice!

You probably have seen Bengt H's thread on boxerville.se where he make his own? I bought a set, but they are for 32mm, not 28.
_________________
I got a historic car, every scratch got a history...

My car, Aug. 4th, 1955 / an early 56: http://www.thesamba.com/vw/forum/album_page.php?pic_id=610438

Glenn · Posted: Mon Feb 03, 2014 2:34 pm Post subject:

Killer work.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

gimmesomeshelter · Posted: Mon Feb 03, 2014 2:48 pm Post subject:

_________________
"I would rather have questions that can't be answered than answers that can't be questioned."

Richard Feynman

Welt · Posted: Mon Feb 03, 2014 3:12 pm Post subject:

txoval · Posted: Mon Feb 03, 2014 7:35 pm Post subject:

How hard would it be to rotate the carb flange 90 degrees? Seems it would be easier to setup the linkage this way.

Manifolds look great, I'm in the middle of making mine (steel, not alum)

Brian Anthony · Posted: Mon Feb 03, 2014 10:49 pm Post subject: Steel manifolds

I just completed a set of steel manifolds. 1-1/2 tubing, 35mm ID and 35mm carbs. 1500 SP heads. Offset bore by 0.050" to provide room for 35mm ID port in head. I know this is the wrong forum, sorry.

Since the new port was offset, I needed to move the intake studs too. It was easier to just make it a 4 bolt pattern.
_________________
1965 Double Cab
1967 Bug, Sedan
1967 Bug, Convertible

I’m not old, but I once knew a man who was alive during the Civil War, and he once knew Revolutionary War veterans.

Welt · Posted: Mon Feb 03, 2014 11:46 pm Post subject:

txoval · Posted: Tue Feb 04, 2014 4:50 am Post subject:

This is the example I am building mine from

Either way, your manifolds are great, and thanks for sharing. It would be great if there are/were more options for SP dual carb manifolds for 36hp engines

mark tucker · Posted: Tue Feb 04, 2014 9:20 am Post subject:

sweet work!!! Im slowely worken towards doing some casting. you might think about adding some bosses tothe intakes on the rear side to mount some linkage like an arm for a bellcrank assy...hm and make the bell cranks in the same box!!!
make sure you have a good thickness at the lower flange aera you dont wast /need any cracking.a little vibration up top is exzadgerated at the head/intake joint. you do great work!! keep it up,make some more stuff!!!

rlmartinez · Posted: Wed Feb 05, 2014 9:51 pm Post subject:

Outstanding work Applause

_________________
54 Bug
56 convertible

Snort · Posted: Fri Feb 07, 2014 7:40 pm Post subject:

Those look great and I like the solid casting work. I've been toying with my own made from dead single port manifolds. Mine have the carb flanges turned 90 degrees. My project has been on the back burner for a while but I did spend some time with linkage ideas a couple of months ago. I'll post the results if and when I get done with it.

txoval · Posted: Fri Feb 07, 2014 8:04 pm Post subject:

Gene Berg linkage works great or even the Scat Linkage...with Scats you need to keep the manifolds lower so that the arms can go under the generator

I plan to use Gene Bergs

faster · Posted: Sat Feb 08, 2014 7:40 am Post subject:

Great work on the patterns and core boxes. Makes me want to start casting again.
_________________
My 59 panel plus 36hp valve covers http://s122.photobucket.com/albums/o265/faster50/59%20panel/

Stocknazi · Samba Member Joined: June 18, 2004 Posts: 5150

Any updates on the 36hp manifolds you are making?
_________________
WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).

"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."

Thomas Jefferson

Welt · Posted: Thu Aug 28, 2014 9:08 am Post subject:

Welt · Posted: Fri Aug 29, 2014 7:44 am Post subject:

Tested the new thingies out. They work!

_________________
1956 Oval
1971 Type 181
1974 Baywindow
1974 Beetle

rlmartinez · Posted: Sat Aug 30, 2014 10:45 pm Post subject:

bdub475 · Posted: Mon Sep 01, 2014 7:55 pm Post subject:

Have you considered making 40hp manifolds? I think there would be a high demand. I know I would buy a set or two.

Welt · Posted: Tue Sep 02, 2014 11:16 pm Post subject:


Hello! Log in or Register \| Help \| Donate \| Buy Shirts	See all banner ads \| Advertise on TheSamba.com

	Forum Index -> Vintage Speed	All times are Mountain Standard Time/Pacific Daylight Savings Time Page: 1, 2 Next
Page 1 of 2