Also, Be sure to check out the
drawing and explanation for the Bovaird & Seyfang...
The following is one of the methods that I use to make intake and exhaust
valves. As you can see, in the first photo, I start out with a square piece
of flat stock. Next I mark the center, and put the flat stock in the 4 jaw
chuck on the lathe and center drill the hole for the valve stem. The second
photo shows the finished bored hole in the plate for the valve stem. Next I
nip off the corners with the torch and clean them up on the grinding wheel.
This helps when you are first starting to turn the O.D. of the valve...
This photo shows the valve stem in the lathe and the diameter being turned that
will have a .002 interference fit with the valve plate. Notice the small shoulder
to press the valve onto and also the chamfer to aid in assembly...
The next step is to heat the valve plate up cherry red with the torch and press
it onto the valve stem. Most of the time it wont take much to assemble the plate
to the stem with the plate cherry red. When it cools you have a nice tight fit.
To make sure the 2 piece valve doesn't come apart I MIG weld both sides of the
valve plate to the stem. You can see that in these 2 photos...
The next step is to put the welded up valve assembly in the lathe and rough cut
the valve O.D. to size. In these 3 photos you can see the process of turning the
O.D. and then facing off the end. Note: I won't turn the 45 deg. angle till I have
the valve seat completed and know the correct size. When I do this I put the valve
assembly in a 4 jaw chuck to insure the 45 deg. valve face is concentric with the
stem. This is very important...
Now to shift gears in a hurry. I wanted to get the brasses for the connecting rod
crank shaft bearings to the foundry, so I stopped work on the valve chest. This photo
is of the pattern which is made from an original brass half all built up with wood and
fiberglass. After some sanding it is all ready to go to the foundry for casting
In these 3 photos I am squaring up and finishing some stock to fabricate the rocker
arm and push rod support bracket. In the second photo you can see what the original
support looks like, and also the bottom plate completed...
Well here I have started working on the valve chest. The heavy wall tube in the first
photo will be part of the main housing. The ID is bored to press the valve seat and
guide into, which is shown in the second photo. I know it doesn't seem real clear
right now but as we go along I think it will get better. Also in the second photo
I am drilling a small starter hole...
Next I've started up the 5 HP Economy which powers the lineshaft. This is for
drilling a 2" diameter hole in the seat and guide part that will be pressed
and welded into the valve chest. The drilling is done to cut down on the amount
of material that has to be bored out. Note: this is not a through hole. It stops
and there is a 3/4" wall left on the end...
These 2 photos show the valve seat and guide being bored out. It needed to be bored
to a diameter of 3 1/8"...
In the first photo I have blued up the valve seat and guide and laid-out what
material needs to be removed. It is the dark shaded areas. Now the little bridge
that will be left in the center will have a hole bored in it when the seat is
machined and this will guide the valve stem. The second photo shows the existing
valve chest where you can see the valve seat and the bridge that guides the valve.
I hope its getting a little clearer...
Here I have drilled a couple of starter holes in the shaded area that needs the
Well its time to stop thinking about cutting the crankshaft down and just do it.
In the first photo I have positioned the power bandsaw under the crankshaft where
I want it cut. Everything is jacked and clamped into place and the vise tightened
on the crankshaft. Turn the power on, and wait approximatly 20 minutes for it to
cut through the shaft. In the second photo you can see the nice cut the power
With some friends help I heated up the flywheel and knocked out the tapered key.
It came out quite easy and nothing got damaged. The reason the flywheel has to
come off is to replace the 40 tooth timing gear that goes on the crankshaft. The
flywheel is all loose now, and I will wait till the gear is ready for installing
before I remove it...
With a lot of elbow grease from my friends, you can see in this photo that the
crankshaft journals are starting to get cleaned up. They really are in nice
shape. Thanks guys for all your help...
Here are the brasses I had the foundry cast for me. They came out really good and
need to be machined now. Notice there are 2 extra sets. Two people that I know need
brasses for thier 10 HP Bovaird & Seyfang engines. The brass to the right is the one
that I built up to use as the pattern...