Deacon, the master, taking a break. Photo by Chris T.
I ran across a master mechanic, in Oahu, Hawaii, at Pro
Street, who recently produced the first Choppers Only Show in Wakiki.
He explained the differences between the Evolution configuration and
the Shovelhead and how you can alter your Shovel for reliability and
better performance. I was intrigued, grabbed my camera girl and went
after the formula.
Note the heavier/thicker Shovel wheel.
First off the flywheels are 4 pounds lighter, saving 8
pounds off the lower end. That's 8 less pounds the engine is forced
to lug around.
"You can go either way with the flywheels," Deacon
said, "although it's easier to just swap them. The new set will
already be correctly clearanced and have a better rod package. Sets
can be ordered from S&S in this configuration."
This shot shows a performance flat top job, a standard
Shovelhead piston and a Sportster unit. Imagine the spark trying to
climb over that Sportster piston dome.
Next, Evolutions use flat-top pistons for an immediate
burn. Shovelheads are equipped with domed pistons and one spark plug.
The flame must travel up and over the dome. That can be corrected
with two plugs, but a better way to go is to use the flat-top piston
configuration like Evolutions.
"Compression ratio is based on how
the bike will be ridden and how much HP is desired," Deacon told me.
"Use flat top pistons or J&E 30 degree entry pistons with S.T.D
bathtub chamber heads."
Here's a shot of the heavier Shovelhead valve on the right and
the lighter stem larger Evolution face for better flow.
The valve train in an Evolution is lighter with smaller
shaft diameter valves with a larger diameter face for better flow and
volume. "Use Kibblewhite or Manley thin stemmed valves," Deacon
muttered and went back to work.
Keeper kit from Precision Machine.
A company called Precision Machine offers a conversion kit
to use Evo valves in your Shovelhead. "The kit contains the keepers
to use Shovel upper collars," Deacon added. "Also use cast iron
valve guides from Rowe for your specific application."
Here's a goddamn stock Shovel valve, lifter and lifter block.
An Evo unit will fit right in.
The hydraulic lifters in Shovels are weak and oil poorly.
The Bolt pattern for Shovels and Evo lifter blocks are the same, so
you can replace the Shovel lifter blocks with Evo units and a much
larger automotive type lifter to improve valve train operation.
Here's the updated Evo valve train configuration. It will bolt
Deacon likes S&S oil pumps and doesn't much care for JIMS
replacement lifters. "Yes, use an S&S oil pump," Deacon snapped and
raised a large torque wrench in my direction. "You will get more
volume for better top end oiling. With more volume you need more
scavenging and the S&S pump delivers this as well. Also, Baisley
offers an overdrive pump gear to provide even more pressure.
A comparison shot of a Shovelhead and Evo lifter.
With the above mods your Shovel won't work so hard to spin
those heavy flywheels and the valve train will be lighter, more
proficient and flow more fuel, air and exhaust. The pistons will fire
more efficiently and won't be subject to as much heat. The only
aspect of the Evolution that you might miss will be the flow ability
of the head design.
That's it, build a Shovel that will last. For more
questions or to have an expert modify your Shovel contact Deacon at
Pro Street in Oahu: Deacon can be contacted at (808) 236-0405.
c/o The Hogpen
94-084 Leokane St. #B
Waipahu, Hi. 96797