Technical Casting an intake manifold from Old irrigation fittings and lawn mower decks

Old Machinist trick for machining gummy aluminum casted alloys. Use kerosene. A little smokey but helps produce a nice surface finish while eliminating cutter buildup.

 

Good to know thanks for the tip !

 

So , I got these carbs from a good friend. I put it out there that I needed 3 97's and for him to keep an eye out for me. He bought a raft of parts from one of his contacts. In the lot were these 3 strombergs that look like they have been nickle plated. He didn't need them so he let me have them. The middle carb has a choke but the top of the air horn is damaged. It looks like it may have been dropped at one time. Every thing else seems pretty good . Even the plating is in good shape so I just cleaned them in an ultrasonic cleaner I bought and put kits in them. The shafts seem good with no excessive wear so I left them alone. I Cobbled some progressive linkage and ca
st some linkage arms .I made a couple of tools to do the job. I made an emulsion tube puller and a short jet wrench so you can change jets without removing the carbs (unless they are wicked tight). I am waiting for some return springs and a fuel line kit and then we'll see if this bugger will run.

 

Wow! What a craftsman you are!
I am continually blown away with the talent and ingenuity that is displayed here.
Thank you for taking us along on this journey.
Now I think I need to up my game and learn some more new hobbies.

 

I am always trying to improve things so I made up another pattern and cast another manifold.
I started with the core pattern because the inside is more important than the outside. Don't get me wrong , I want the outside to look good but if it doesn't flow well what's the point.
I made the patterns from hardboard and MDF and made them so I can use a router pattern cutting bit so the pieces will be exactly the same.
I cut some grooves in the core pattern to increase the surface area , assist in vaporization and help with turbulance.
Maybe overthinking a bit , it's still just a street motor but I can't not try to make things better.
Once the core pattern was finished I coated it with epoxy primer and then a couple of coats of clearcoat. I sprayed some silicone spray on the core pattern then layed up four layers of fiberglass cloth and resin. This is the mold that I will use to make the core out of fine sand and epoxy resin.
I wanted to change a few things on the manifold. I made the mounting flanges bigger and made sure I got the carb flanges going the right way. I made a heat stove for under the center carb for water heat.
The first manifold works pretty well but I wanted to fix my mistakes.
I also welded up a set of headers , they should flow better than the split manifolds that are kinda restrictive.

 

Looks great, I like the improvements

 

Hey, Jethro;
Not to be Rude, just really curious. Did you do any flow-testing, maybe even wet? Or have you "proofed" it w/a back-to-back dyno test of stock->your manifold n carbs? Latest looks good, but I wouldn't go by my "eyeball-engineering" guestimate... . Could be interesting to say the least, + maybe bragging rights... . All the header tubes look same OD, what calcs did you use to determine the ID, esp of the siamesed ports? Not being funny, I'm quite curious & always looking to learn. Different books/authors & even mfgrs differ in opinion(s). Nice posts casting info, btw.
Marcus...

 

Hey Marcus ,
No real scientific testing , it will be "seat of the pants" testing. My design ideas came from studying other inline manifold designs and any info professor google has to offer. As far as the headers the siamese center ports are 1-3/4 tube and ends are 1-1/2 . I calculated the volume of the big tubes and tried to match the volume on the end tubes . I know the serious GMC racers have used step tubes in their headers. I'm just trying to get a little more efficiency. I'm sure the headers will be better than the "log" style manifold.
I have a bigger cam coming so that should add some more airflow....maybe even some more horsepower.

 

Ahh, Empirical testing... (AKA: cut n try... ).
Just was wondering how far your curiosity took you down the rabbit-hole... . You're on the right track. If you're interested, Port & FlowTest cylinder heads by David Vizard is a good book & includes his recipe for a very low-buck flowbench that works well. + flow/design discussions on manifolds/etc.
Also, you might want to search out Headers by ED info. Guy knows what he's done/doing, but his proven info/data that works, conflicts w/most header mfgrs/magazine-writers opinions. Worth reading.
Marcus...
Might have a market awaiting you, especially iffen you've got proven "bragging rights"... . & even for the cool factor, + "it's *now* available" & you don't have to search forever for a used unobtainium one... : .

 

Very cool @Jethro Love that you put Canada on the intake as well. Otherwise all them crazy Americans will try and steal your design! We gotta get together more and do some bench racing!

 

Awesome thread

 

How did you make the lettering so perfect? It is a beautiful piece of backyard work.

 

Love the latest design. Only improvement suggestion would be to make the Canada/BC part bigger and more prominent.

 

I used those little plastic letters that go on menu sign boards.....you know the ones that you rearrange to spell swear words while you wait for your table.