TheSamba.com :: View topic

Wed Jun 03, 2009 4:02 pm

I thought I`d just start my own thread on how to make 36hp valve covers. The first thing and the hardest part is coming up with a pattern you can`t just have an old valve cover recasted because aluminum will shrink just under a 1/4" per foot. So what i did was dig out the old wood working tools and build one from scratch. The trick is making everything bigger to make up for the shrink. And if you plan on make alot you have to make a double shrink pattern to ended up with aluminum pattern that will last. So heres the pictures.

The wood pattern.

The first casting.

After alittle polishing.

This one isn`t just right so it will become and ash tray. The holes are off alittle and it`s a bit tight on the sheet metal no room for the engine seal. Anyway I know what I need now and hope the next one will be right on. 8)

Wed Jun 03, 2009 4:08 pm

Nice work! and I like the looks of the cover

Wed Jun 03, 2009 4:17 pm

Thanks, I need to make some adjustments if I get time I`ll do it these weekend.

Wed Jun 03, 2009 5:27 pm

Looks pretty sweet! How do you plan to true the seal area?

FWIW, they'll cool best if left rough, but then they wouldn't look as spiffy. :lol:

- Scott

Wed Jun 03, 2009 5:34 pm

Looking good. 8)

Wed Jun 03, 2009 5:53 pm

Nice, are going to be selling the final versions when done?

Wed Jun 03, 2009 5:54 pm

I think I`m going to make a new pattern and use most of the parts on the old one. I`ll lower the top to match the bottom for the seal fit and also adjust the top so the holes match better. This happens all the time with the first pattern and changes have to be made when its the first pattern you`ve ever made. If I would have test fitted the wood one to the motor I would have found it was tight but I didn`t want to remove the rockers and adjust the valves again so now I have to pay. 8)

Wed Jun 03, 2009 6:00 pm

splitpile wrote: Nice, are going to be selling the final versions when done?

If I can get them poured for a good price I will. Right now it`s one at a time and done by hand. I thing the owner of the foundry is just having fun with me thinking I`m crazy but when I showed up with a pattern that I made he had a funny look in his eyes.

Wed Jun 03, 2009 7:59 pm

Looks like they are going to be real nice, as well as updated. Good luck on introducing a NEW 36hp product. We can always use more of that!

Burly

Mon Jun 08, 2009 7:04 pm

You sir, are a craftsman. Nice work. 8)

Tue Jun 09, 2009 6:13 pm

69 Jim wrote: You sir, are a craftsman. Nice work. 8)

Thanks,
But its not as hard as it looks. I was hoping to make up a new one last weekend but got side tracked with other things the wife needed. Anyway I did pickup the needed wood and should have the new and approved model made soon. If I get everything right and can get them poured it`s looking like about $150.00 a set for now(thats one at a time ). But my goal is to have 3 to 4 poured at the same time lowering the price but not polished. Anyway the cost has been all on me so far and when I finish with my maddest it souldbe as good if not better then the older vintage covers. Give me a week and I should have a new pour. 8)

Fri Jun 19, 2009 8:28 pm

Update. Well I just finish the new pattern and resized and made all the adjustments to fix the problems with the first one. The first of next week I`ll have it poured and hope it will be right on. This one is thinner and alittle lower to give room for the engine seal and should also be lighter as far as weight. The old one was very heavy.
Have a look and I will get it right . 8)

Sat Jun 20, 2009 3:02 am

very nice, excellent craftsmanship.

Sat Jun 20, 2009 9:11 am

ALUMINUM AS 3 PERCENT SHRINKAGE

MOLD MAKER
TOOL AND DIE
GLENDALE CALI

Sun Jun 21, 2009 8:03 pm

Are you planning on doing some machining of the surface where the valve cover interfaces with the gasket? I'm afraid that without a flat, smooth surface you are going to have issues with oil leakage around the valve cover gasket. If you have access to the facilities I'd make a jig to hold the cover and then use a CNC endmill to machine that surface.

Don't take this a criticism BTW - You've done some remarkable craftsmanship that most people only think about. Excellent work.

Wed Jun 24, 2009 2:18 pm

Update, Got the new and improved casting of the second pattern back today. Yesterday they poured one but it came out bad so today they repoured it hotter and it came out good but rougher from the heat. It needs alot of cleanup where some of the corners broke off from hand packing the sand and not using a air ram on it. The wood pattern is somewhat fragile and care has to be taken or it could break. Anyway the shrink came out just right very pleased and after fully polishing this one inside and out it will be the main pattern for making many more. I`ll post more pictures after I get it polished up.

Wed Jun 24, 2009 2:20 pm

wow impressive work with out cnc!! old school, pure essence of vintage speed...

cheers

Wed Jun 24, 2009 2:24 pm

Thanks

Wed Jun 24, 2009 5:33 pm

Well I had to see how it fit so after alittle polishing on it went. Very pleased the seal has plenty of room it looks like its touching in the picture but its not. Now I have to finish polishing the rest of it and back to the foundry.

Mon Jul 06, 2009 11:12 pm

faster wrote: Well I had to see how it fit so after alittle polishing on it went. Very pleased the seal has plenty of room it looks like its touching in the picture but its not. Now I have to finish polishing the rest of it and back to the foundry.

Any more progress?