The camshaft was made from drill rod, first the blank was set up between centers in the lathe, all of the lobe positions and cam bearing journals were marked out and turned to their finished diameters. I decided to make a jig to copy a full size camshaft to the size I needed for my engine, I know this may seem like an expensive method but, it saved a lot of time and design work for me. The cam I choose to copy is not a good choice for this engine; I had not originally intended to supercharge this engine. The problem is that with a supercharger you need a cam with very little or no overlap in the valves, my situation is that when the supercharger is putting out boost some of the intake fuel mixture is wasted and being blown out the exhaust valves, not very efficient. The cam I chose was intended for very high RPM's with the majority of power being produced at the upper end, non supercharged race engines use the valve overlap to create a scavenging effect that actually helps draw in more fuel and air mixture. The engine does run great but I will probably build the correct camshaft latter on. The cam I chose to copy is made by Crane Cams, it is a FireBall 2 302H, its timing at the lifter is intake opens 39 deg. BTDC closes at 83 deg. ABDC, exhaust opens 83 deg. BBDC closes at 39 deg ATDC with 302 deg advertised duration.
The jig was made and my camshaft blank was placed in it with the shaft riding in sealed bearings at all the cam journal locations, the whole assembly was mounted on the milling machine table and indicated true. The jig is set up to reduce the full size cam to a quarter of its original size, a gage block is set between the table and each full size lobe, a variable DC power supply rotates the full size cam and miniature cam at the same RPM, as both shafts rotate the whole assembly tilts on its support bearings. I first used an endmill to remove all but about 0.005" of the material from each lobe. The blank was then taken back out of the fixture and heat treated, you want to make sure when doing the oil quench to support the shaft from one end and dip it strait down vertically into the oil, this will reduce any warping in the shaft.
I then covered the entire milling machine and everything except the lobe I was working on at the time with plastic sheeting. I securely mounted my tool post grinder on the quill of the Bridgeport, and controlled the depth of grind by using the knee of the mill, you want to be very careful to cover everything from the grinding dust, if I was to get anything between the gage block and the full size cam lobes the job would be ruined. The feed was kept very low 0.0005" per pass and I saved the last 0.0005" on each lobe for a final grind to make sure each lobe had the same base circle and max lift.
I am going to add a complete section on building and using this cam grinding jig and take photos of the process when I decide to build my new cam for my engine.
LIFTERS AND LIFTER MOUNTS
The lifter mounting blocks were milled out of 6061 T6 aluminum, all lifter holes were located, drilled, and reamed for phosphor bronze lifter guides. The bronze guides were then pressed and bonded in the bores with Loc-Tite retaining compound. Lifters were turned on the lathe from drill rod and the recesses for the pushrods were made with a ball nose endmill. The lifters were then heat treated.
The pushrods are made of drill rod parted to length in the lathe and their ends rounded with a file and hard stone to get a nice finish.
CYLINDER HEADS, VALVES, AND ROCKERS
The cylinder heads are made of 6061 T6 aluminum solids; all work on the heads was done in the milling machine. I decided not to take the heads completely apart because it is so time consuming to put them all back together, I did pull a couple of valves out and the valve stems, guides, and seats look great, no signs of wear. The heads on this engine were by far the hardest parts to make for me, not completely drawing out all the fastener and port locations on paper first resulted in me making three sets of heads.
The valve guides were turned from phosphor bronze and pressed and sealed into their bores, I made the valve guide and seat one piece, referred to as a valve guide cage. The seat of the valve cage was turned with just a tiny taper. I made the valves from drill rod and used a woodruff keyway cutter to machine a small slot in the face of each valve. I had heard that you should never lap the valve to the seat with lapping compound, I pressed the valve stem through a small piece of 600 grit abrasive paper with the abrasive side towards the seat on the valve, the valve was then placed in the guide cage and rotated back and forth with a small screwdriver applying the pressure. This process was repeated on all the valves, until a nice seal was formed. The ports for all the valves were then located and drilled, the point were the drill breaks through the valve cage was then deburred and beveled with a dental bur.
The valve spring retainers were turned from drill rod and lock in place, a small circlip. The valve springs were selected for there pressure strength and were a purchased item.
The rocker arms were made from aluminum and bearing pivots installed, the ratio of the arms is 1 to 1.6. Roller tips were made from drill rod and the lash adjustment screw is an allen cap screw with the hex milled out with a ball nose endmill. The arms are mounted on a solid shaft with brass shim washers between each rocker and aluminum spacer. Spark plugs are 1/4-32 Rimfire.
The heads seal to the cylinder blocks with Viton o-rings. The recess's for the o-rings was done before I had my CNC mill, I used a Volstro rotary milling head in the Bridgeport with a properly sized ball nose endmill. The heads seal great and I have never had a leak or damaged o-ring, Machinery's Handbook will give you the proper size and depth to cut the o-ring seat.