Stafford Motor Speedway has made the following clarification to its SK Modified® SPEC Engine rulebook effective immediately.
20E-
5.7 CRANKSHAFT
A. Crankshaft must be a SCAT Cast Steel or SCAT Forged Steel
Crank #9-350-3480-5700, or a
CALLIES Comp Star series steel
crankshaft. The Journals may be machined as
follows: Main Journals may be .020" undersized, Rod Journals may be
.030" undersized. The SCAT and CALLIES crankshafts must be 3.480" stroke. If you are currently converting an existing SK Engine over to the SK
SOEC Engine, you may use your existing GM cast or forged steel crankshaft, and
it must weigh a minimum of 50 pounds and must be 3.480” to 3.495” in stroke.
You must contact the SMS Tech Staff to notify them of your intent to run this
pre-existing crankshaft. NOTE: The GM style crankshaft will be allowed until
the conclusion of the 2012 season. In 2013 the only allowable crankshafts will
be the SCAT or CALLIES as described above.
B. Small journal, or Honda pin
crankshafts are not permitted.
C. NO machining or polishing of the crankshaft counterweights
allowed. Normal engine balancing is the only acceptable modification
that can be performed on this component. No painting or Teflon coating.
Crankshafts must maintain the manufacturers’ appearance.
D. Minimum crankshaft weight is 47 pounds (with timing gear and pilot bearing) for
the SCAT and CALLIES crankshaft, and 50 pounds for the SK pre-existing GM
crankshaft.
E. The only OEM magnetic steel elastomer type
harmonic balancers permitted are the Power Bond # PB1012-SS, ATI # 917260
& 917320 and the BHJ # CH-IBF-6-C (NOTE: The ATI & BHJ can be rebuilt).
Cc:
Tom Fox
Jay Shea
Chuck Zentarski
Mark
Arute