The plaster cores had to be duplicated in sand for the casting process so I molded up two-piece fiberglas molds for each plaster piece. Photos 1 & 2 show these 'glas molds. # 1 is them assembled and #2 is them taken apart. There are a couple of processes to make the final sand cores, both require special sand formulations. The first is using a sand that is coated with a special resin that sets up hard with exposure to CO2 gas. My foundry guy didn't have any of that sand so he used the second method of sand coated with a heat setting resin. He tightly packed the molds with the resin coated sand then baked them in an oven @ 250F for a short time and came out with rigid sand versions of the plaster cores shown in the previous set of pictures. The 'glas withstood the heat very well. It is important in the casting process to use sand instead of plaster for these cores since it will crush as the aluminum cools and shrinks, protecting the weak hot metal from tearing and because the sand is porous, gasses can escape instead of remaining in the aluminum causing devastating porosity.
Next step was to make all the casting molds and patterns from the wood pattern I made. Each runner and passage on the inside of the manifold wold require a separate core mold so that was the next step. Photo 1 shows how I did that. I first made a paster of Paris 2-part casting of the wood pattern. Then I systematically formed molds for each runner (took some anatomy scratching to figure out who went where on each layer!), forming 1/4" clay walls that represented the final aluminum body of the finished manifold. The remaining cavity represented the hole in the final manifold.
Each of these cavities were cast in plaster of Paris. Once all parts were cast, I made a wood jig to assemble them to be sure they all fit perfectly together and photos 2 & 3 show the 'holes' in place on that jig. I needed to be able to reproduce each of those plaster runners in core sand.
Note the ends of the runners interlock and also extend past the board, fitting into a notch. There is a similar boss on the carb base part of these plater pieces that fits into another boss in the base of the board. These holes perfectly accept the bosses you can see on the wood pattern in the first installment. Thus they index the runners (called cores in casting circles) into the final casting cavity.
As I have said many times, I will never put an SBC in any car I ever build. Also, I have mentioned many times the 230cuin straight 6 I put in my son's '36 Pontiac 4-dr sedan. I wanted something more than stock and the siameze intake ports on that head are definitely not performance oriented. Add to that the small size and terribly unequal length of the log intake manifold and th whole mess needed major TLC.
I decided to try to cast up a 180deg aluminum intake w/ equal length runners to all 6 cylinders. I first had to determine of I could isolate the individual ports on the head and the answer was yes. The ports have a bolt stand down the middle so I put a divider behind the bolt stand using screen wire and Devcon Liquid steel epoxy. Worked like a champ. I first brazed a filler in front of the stand as shown in photo 1.
Next I designed the manifold on paper and carved a pattern from mahogany as shown in photos 2 & 3. I made it slightly larger than the finished unit to allow for shrinkage of the cast aluminum. The two runners going to the front and rear sets of cylinders are pretty straight forward. The two inside cylinders required a little more ingenuity. All runners are equal length and they are ducted for equal timing into the two sides fo the divided plenum.
These photos are to answer questions in active threads but I though they would be of interest here too. The first couple of photos are of the buffing wheel I put together a couple of years ago. It is an old 3hp 3600rpm swimming pool pump motor mounted on a pipe which is in turn mounted on an old car wheel base. I made a very sturdy shroud to cover half the polishing wheel to collect some of the large quantity of fuzz and dust coming off the wheel but also to deflect the parts being polished when they are jerked out of my hands which happens often. Pro shops have their wheels unshrouded which is very dangerous 'cause grabbed parts can be carried around the wheel and flung into your face. Not good. The shroud is made from split exhaust tubing bend and sheet metal. The wheel is held by an arbor that affixes to the motor shaft and is available from any polishing equipment supplier.
The second tool show in my mondo home-made axle shaft removing slide hammer. I welded it up from the obvious pieces of scrap adn with that full sized wheel hub/brake rotor as my slide hammer, no axle can resit it long! Of course it is for use on Hotchkiss (Ford 9", Olds and Pontiac late 50s/ early 60s), not Salisbury type with the C-clip held axle shafts.
The second home