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Technical CASTING, Made my own cast alloy nailhead valve covers

Discussion in 'The Hokey Ass Message Board' started by Carb-Otto, Nov 15, 2006.

  1. Carb-Otto
    Joined: Feb 12, 2006
    Posts: 332

    from FINkLAND

    Finned stuff from Finland! :D

    I didnt like the shape of Moon valve covers (for nailhead) and Offenhauser has big logo on the center, and I didnt like that either. Moon looks way too billet and vintage-parts were too hard to find, so I decided to design my own valve cover model.
    Long story short;
    First, I made wooden valve cover. That took the most time...
    Another picture;

    Then I painted it and took it to foundry. There they sand-casted it.

    When I got it back to home-garage, I polished it
    Another pic;


    So there it was, shortly.
    Small batch of these was made, at the moment, I still havent got 'em all from the foundry. I need few pairs myself, and one pair is already reserved. Rest will be sold.

    As you notice, there is not breather or oil-filler tube. I'm currently fabricating valley cover which also will have some high fins, breather in original place, and short oil filler tube.
  2. Did you make the buck a little oversize to account for shrinkage of the
    turboroadster likes this.
  3. Do you have a picture of the underside of your wooden form? I would like to see exactly how you made it.


  4. Carb-Otto
    Joined: Feb 12, 2006
    Posts: 332

    from FINkLAND

    Yes, I did.
    Also, there can't be sharp corners, they will crack hardened casting sand. I've studied to furniture-carpenter some ten years ago and I'm carpenter as a trade, but this was my first sand casting buck ever.

  5. old beet
    Joined: Sep 25, 2002
    Posts: 5,750

    old beet

    Cal Custom style valve covers for 318 Poly engines--Craig down under, but sent to L A for polishing......OLDBEET
  6. old beet
    Joined: Sep 25, 2002
    Posts: 5,750

    old beet

    Web site ain't workin!
    19 Glendale St. Gorokan
    NSW Australia 2263
    61-2-4392-2215.......Or ask QQMOON
    Joined: Aug 21, 2006
    Posts: 1,989

    from Houston

    Great looking cover thats for sure.
    I too wanted something that did not exist in the form I wanted so I went this route to make(have cast) aircleaner.
    Like some addressed there are shrinkage factors to consider when making a piece that needs some high tolerances. In order to have something cast there are some things that you cannot do like having negative angles or they (the foundry) will never get your master out of the mold to make the shape. All curves must have at least a 0.06 degree radii and also have a 0.03 in. positive angle( so it can be pulled out of the mold)
    Shrinkage for standard aluminum is 5/32 in. per foot. So if you are casting something long but skinny you will see a noticable shortening in the length.

    As far as what I wanted...I love the look of a Thickstun air cleaner, but I wanted one to fit a four barrel carb. This is what my first prototype top looked like.


    This was made of wood, bondo, paint, and lots of elbow grease.
    After making this I realized that some changes needed to be made so a whole new one was made.


    It had wider spaced fins so that it would be easier to polish down the road. This second shot shows the top and the bottom(yellow) together.
    If you think you can't do this...your wrong.
    anybody want to see more? I don't mean to hijack this thread but I thought maybe it fit in with the subject.

    As far as cost.. it was close to $120, including shipping back and forth to the foundry.

  8. Carb-Otto
    Joined: Feb 12, 2006
    Posts: 332

    from FINkLAND

    Great work, Low Cab! Have you already taken it to foundry? You had there lots of important stuff told, I want to tell something also.

    Ok, here is something about my valve cover -project. But first, I'm not educated to casting works,
    so these are things that I've found when I've searched, I've noticed, and got answers from some old carpenters.

    I started with birch, and ended up to cast aluminium...
    First thing was to measure original valve cover, nobody wants valves to hit covers.
    Writing those measures also to somewhere is not a bad idea.
    First, when this piece of birch was still square, six grooves were made, in two different heights, which you propably notice here;
    Second, another side was drilled hollow. It got it's shape with chisel and sanding paper. Gotta admit, also some Bondo. (I feel shame for that...)
    Now this piece had those important, required shapes. Then again, with chisels and sanding
    machine and -papers , outer shape got it's shape. This is phase that takes more time that I thought.
    Also, it should look same from both ends and sides.
    I wanted to bolts go to same height with fins.
    Buck was painted, it makes easier to get it out of sand.
    As Cast -finish looks like it is hardened sand...

    Also, remember that they have to pour that melted aluminum inside mold from somewhere... here is what it looks

    As you know, polishing is not fast, but makes it looks soooo good!
    And then generally;
    This part is like bowl, it has to taper, so it is possible to get it out of the mold.
    Also, sharp corners can't be used, they must be radiused. If they're not, casting sand will crack.
    Casted piece is 1% smaller than original model, which has to be noticed when piece is fabricated.
    Therefore, you can't just take all those vintage parts to foundry and ask them to do same thing again. Damn!

    volvobrynk likes this.
    Joined: Aug 21, 2006
    Posts: 1,989

    from Houston


    Thanks for the compliment
    I know the amount of work that goes into making something like yours.
    This was my prototype on the engine. Pretend it's a Flathead.
    volvobrynk likes this.
  10. Polara
    Joined: Jan 22, 2006
    Posts: 85

    from Indy

  11. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,375


    We have a HAMBer that does this stuff for a living. You may check with him... he's our very own Dennis O'brien and he's a SUPER nice guy and easy to talk to! He's also on our Vendor list... O'brien Truckers. Maybe he could support some of the home brewed one-off parts some of us come up with around here. Here's the website:
    Joined: Jun 2, 2002
    Posts: 9,635

    Classified's Moderator

    Did you have to "face" them in a mill to be sure they are flat and even at the mating surface? I hear this is a big problem with the 348/409 Offenhauser covers.

    I would think you could make a fortune building valve covers that look like yours for any engine out there. I would sure be interested in some for my 348.

    I agree on the Moons, they are TOO refined.
  13. Did you use any special alloy or heat treatment?
    Very cool!

  14. roddinron
    Joined: May 24, 2006
    Posts: 2,676


    That's some really beautiful work! I grew up next to a foundry, so I've played around with sand casting a little. If anyone wants to try it themselves, you might find this interesting.

    OOPS I just realized Polara already suggested this
  15. RocketDaemon
    Joined: Jul 4, 2001
    Posts: 2,082

    from Sweden

    [​IMG] how bout these olds covers?
  16. Ted H
    Joined: Jan 7, 2003
    Posts: 312

    Ted H

    Great work and fantastic results ! Teck week has just started and you've got it nailed already.
    For those of you considering making your own patterns for casting there are special rulers made that compensate for the shrinkage factor. The shrinkage is different for each type of metal being cast, ie aluminun, cast iron. bronze, ect. so you have to get the ruler for the specific metal being cast. I don't know just off hand where to get the rulers but any of the home casting sites should have the info available.
    Ted H
  17. yes they do and they're EXPENSIVE. i went to 5 different ones and got quotes from $15k to $30k to do a run a 1000 ( in investment casting). i was thinking to do sbc, nailhead, 348 and buick straight 8 but too much $$$ for me. the computer one was a joke not what it was really going to look like, i just could'nt find the other picture on my computer.

    Attached Files:

  18. Mojo
    Joined: Jul 23, 2002
    Posts: 1,865


    Wonder if lost wax and lost foam method would work too? Basically, you make the part out of wax. Then make the mold, pour the aluminum. The aluminum melts the wax out and fills in the void. Syrofoam works too, I was reading about it the other day actually.
  19. LOWCAB
    Joined: Aug 21, 2006
    Posts: 1,989

    from Houston

    Metal shrinks as it cools. Therefore, a casting is larger when it is hot than after it cools. When making a die, the diemaker has to make the die slightly larger than the finished casting.. The amount of shrinkage depends upon the type of metal being cast, and on the whether the mold will cool quickly or slowly. For small castings, the shrinkage rate is:

    Iron - 1/8" per foot
    Steel - 1/4" per foot
    Aluminum - 5/32" per foot
    Brass - 3/16" per foot

  20. Wow, that's a awesome looking valve cover Carb-Otto

    If you have any extras that you plan on selling, I'll buy a pair for (insert drum roll) my 59 Buick wagon.

    Scootermcad - thanks for the kind words.

    JimV - I believe that Cumberland Foundry is a ferrous foundry - i.e. cast iron vs. aluminum/brass/bronze.

    The angle that you need on the pattern (which is what the foundry types call the master that you make the mold from) is called the "draft angle" and I use 3-4 degrees as a rule.

    And as for shrinkage, I use .013" (thirteen thousands) per inch for my aluminum patterns. So that works out to .156" per foot which is suspiciously close to 5/32" per foot.

  21. I just read this thread, and WOW! do those valve covers look beautiful.

    There's been a lot of talk about shrink factors; there are special rulers ('shrink rules') that pattern makers use. Google "shrink rule" (keep the quotes) or click here. Easiest way to go, but you can also just add 1/8" or 3/16" per foot (depending on what kinda' metal you want to cast).

    Also, about WA foundries; there's a little one I saw between 1st & 2nd ave south of the ball parks (in Seattle); somewhere near the Sears store. There's also a big one (olympic?) on airport way near lucille street. And I think there may be one or 2 more here in town.

  22. Shifty Shifterton
    Joined: Oct 1, 2006
    Posts: 4,964

    Shifty Shifterton

    Couple other tips from a foundryman

    Try to make the walls somewhat uniform. Any thick areas will require a riser or gating to prevent shrinkage defects upon solidification. Example, if the rails and ribs on this valve cover would have been doubled in thickness, would have presented an issue as they're on opposite ends of the casting, and both need fed by a gate or riser. Common problem area is anyplace you put a mounting boss, those tend to be thick.

    Make your wood pattern somewhat durable, in order to pack the sand around the buck, there's some force involved.

    Shoot for one flat side with all the draft angle coming off the flat. The pattern will be mounted to plywood or other flat sheet to make the mold. If there's no flat, then it will have to be sliced, mounted on BOTH sides of the plywood and have draft accordingly. It is possible to do loose piece molding without mounting the pattern but you're asking for a higher price, lower yield, and more flash on the finished piece.

    The best thing I could recommend is to visit the foundry with something similar in hand. They will clue you into the blind spots. I make a decent living trying to undo what not-foundry-smart design engineers have done.

    Good Luck, and don't be afraid to try. If you can build a hot rod, you can make castings. But be patient, it's as much an art as a science.

    Edit- almost forgot, nice craftsmanship man!
  23. buickvalvenut
    Joined: Oct 29, 2008
    Posts: 660

    from Rialto

    I'm getting ready to make a master but seems the web cause more confusion than anything. I keep reading different things regarding shrinkage. Wich one is it? 1/8,5/32 ..
  24. Aluminum is 5/32" per foot shrinkage factor which equals out to .156" per foot.
  25. Badass. Wish I could save all these favorite techs. Sweet job that it is 8 years is your valve cover holding up ??
  26. Inkman
    Joined: Apr 12, 2013
    Posts: 23


    Very nice work, I really like your design.
  27. If I were making a pattern for something like a valve cover I wouldn't start with a solid block. I would build up a hollow block from 5 individual parts glued together. The needed "draft" would be created with angle cuts on a table saw. The needed radii inside can easily be created with metal filler.
  28. I have my own small foundry here. Good for small parts like pistons , Wheel hub caps or centres. Small brackets and such. Had an awful lot of fun doing it and there are some of my pours on youtube. It is a very interesting hobby and could quickly become addictive. Now when I need a small part I usually pour it. I had done a tunnel ram manifold top in the nineties the way these covers were done making a wooden mold and taking it to foundry. BTW there are foundries all over that most of us don't realize are there. Biggest problem with home casting is getting a big enough pour. On page 29 of the current issue of Chrysler Power Magazine (available in many Walmart mag racks) there is an ad for Foundry Works, Bell Gardens California. It says, "We would like to help you with you next project. Anything made out of aluminum. From small emblems to 600 CID hemi blocks." The photos are very interesting in the ad and are worth the purchase alone.
    BTW Through a stroke of luck I was able to fly to Finland on a recent trip to Vienna. My compliments to your land and your countrymen.
    At the end of my foundry experiments I became enamored with lost foam method. Blue foam you can buy at Lowes or Home Depot. It is absolutely unbelievable what you can do with that. If you made a part with that any foundry would bury it and pour it for you. You need to have a sprue (in) and a vent (out)
    Last edited: Aug 29, 2014
  29. toucan
    Joined: Feb 15, 2009
    Posts: 1,083

    from sc

    very cool project!
  30. Mojo i know this is old but in lost wax casting you use a wet slurry similar to ceramic to coat the wax. The wax is burnt off in a firing process prier to the pore witch also removes moisture that would causes an explosion
    Lost foam casting can be done in one of two ways using sand or a slurry
    Thare is allot more to die-casting and die design then that

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