Editor’s note: This month, guest writer Kevin Pulver has
written an interesting article on fabricating a cylinder head for
his circa-1915 Champion. A very unusual engine, it was manufactured
for Lininger Implement, Omaha, Neb., by Hercules and based on a 12
HP Model E.
The head (and most everything else) was thrown
away when my 12 HP Champion was converted to a log splitter. I
wanted to cast a water-cooled head as original, but foundry work
was estimated at $3,000. It may have been a Gas Engine
Magazine article about an engine totally made of steel and
welded together that got me thinking about fabricating a head. I’m
not a machinist, but after reading books and dreaming of
do-it-yourself pattern making, sand casting and iron melting, this
method seemed easy by comparison.
A God-given imagination let me see the plan before I ever made
the rough sketches that were our prints. My wife, Maria, encouraged
me to work on it when business was slow. Through Harry’s Internet
engine page (www.SmokStak.com), I met Joel Mosley three hours away
in Omaha, Neb., who re-cast his rocker arm for me, and took me to
measure his 12 HP Economy when I started work.
I should have kept track of time, but I would estimate the
project took 80 hours. My friends Joe Dittrick and Bill Wehrman let
me use their machine tools, and my brother-in-law did most of the
welding.
We started with two 1/2-inch thick plates for the top and
bottom. First, I tacked them together, and drilled the five
head-bolt holes. Next, I located where the valves would center and
drilled 1/4-inch holes. The intake port was made up of 2-inch gas
pipe fittings. For the exhaust, I cut 3-inch pipe wedges to get the
tighter radius necessary to fit the available space between the
plates. My friend Bob Clark gave me the idea to first mock up the
ports from PVC pipe. I remembered enough from watching Lyle Clemens
build irrigation risers to get my pipe marked out. After a bit of
trial and error with my DeWalt sliding compound miter saw, I knew
the lengths and angles I needed and copied them in steel on the
band saw.
I turned tapered valve guides from 1-inch round stock, drilled
1/4-inch. The two ports were drilled on the lathe and mill to
accept the guides, and I used round centering plugs and 1/4-inch
ready rod and nuts to jig them for welding. The same 1/4-inch ready
rod was used to clamp the port/guide assembly to the bottom plate.
Next, 3/4-inch steel pipes were lathe-cut to go over the head bolts
and sandwich between the two plates. They would spread the plates
and seal the water jacket. Slots were milled in the bottom plate to
correspond to water jacket holes in the block.
The plates were cut round on the lathe and a relief was cut for
the 1/8-inch outside band and weld bead to go between the two round
plates. I foolishly cut the corners off with a torch, which
work-hardened the piece. It took lots of bit sharpening and hours
of turning to knock off the high corners and get it round. When I
was almost finished, I figured out my center was off on my 4-jaw
chuck! I had barely enough stock left to clean it up upon
re-centering. The top plate 1/4-inch holes were drilled to 1-inch
to let the valve guides pass through. Thermo-King sheared a piece
of plate for the band, and Hastings Equity Grain Bin rolled it for
me.
After all the pieces were ready, we assembled them on the
engine. We tacked the intake and exhaust ports to the bottom plate
then disassembled and welded them. It took both MIG and stick
welders to reach some tight spots on the exhaust and others. Next,
we reassembled, wrapping masking tape around the 5-head studs to
center the pipes on them for correct fit. We were concerned about
warping, but the top plate with 1-inch holes dropped right over the
valve guides and up against the “spreader” pipes. It was all
clamped tight again and welded. The head had to be pried off the
studs, but when the hot, gummy tape was removed, the head slid on
and off beautifully.
Cardboard templates marked the band to fit around the ports and
a jigsaw cut it out. Homemade hose clamps pulled it tight and it
was welded. We used a hole saw to rough-cut the valve seat holes in
the bottom plate, using the 1/4-inch holes as centers.
Next, the valve guide holes were drilled oversize and reamed to
1/2-inch. A pilot was used in the guide holes for a boring bar to
finish-cut the rough holes that will be our valve seats. Scrap
steel formed the pushrod guide and rocker arm pedestals. Lots of
valve train geometry was studied on the engine before these parts
were welded solid. The bottom plate did warp a few thousandths and
we had the bottom surfaced.
Valves were made of 1/2-inch drill rod and old scrap steel plugs
from hole saw cuts. Center holes were opened up to 1/2-inch,
counter-bored, stems pressed and welded, then chucked on the lathe
and turned down and ground. I couldn’t find 3-inch seat cutters, so
I glued emery cloth to the valve face with weatherstrip adhesive. I
chucked the stem in my cordless drill, pulled it in and spun it
until I had a narrow seat. Then I lapped and blued them, and they
came out pretty good. Lastly, washers were soldered to the head to
resemble the castings where the head nuts go. The engine started
and ran on my birthday, but that’s another story.
Contact engine enthusiast Kevin Pulver at:
pulverk@alltel.net
Glenn Karch is a noted authority on Hercules engines.
Contact him at: 20601 Old State Road, Haubstadt, IN 47639;
glenn.karch@gte.net
