Pro Stock (rev. 1)

Naturally aspirated class. No power adders permitted. No 4.9” and 5” bore spacing big blocks (Excluding Fords)

Body and chassis:
-Lexan/plexiglass window replacements permitted but must appear stock. No visible bracing,
screws, rivets, etc. permitted.
-Functioning lights required.
-Sponsor lettering restricted to vehicle glass only.
-Light weight body panels allowed
-Stock style front suspension required. Bolt in replacement components allowed.  Non O.E. style components subject to weight adder.
-Ladder bars and 4 links permitted. See weight adders below
-Stock fire wall and location required. Modified or non stock firewall location subject to weight adder.
-Small rear wing permitted
-Forward facing hood scoops permitted. See weight adders below

Exhaust:
-Mufflers required. Must be commercially available units, no home built mufflers. No gutting of
mufflers permitted. No inserts style mufflers
-No max pipe diameter

Induction:
-Any type permitted. See weight adders below

Cylinder heads:
-Non Conventional Big block heads add .25lb/ci. (N/C heads include Buick, Big Chief style heads, etc.)
- All canted valve small block cylinder heads + 100#
-10 to 14 degree heads +100#
-15 to 17 degree heads +75#
-18 to 20 degree heads run @ base weight
-20 and over degree heads deduct 50#

Big Block Prohibited head list:

Chevrolet
-Profiler 12 degree Hitman #184
-Brodix PB-1200 and PB-2005
-Dart Big Chief II 11degree #18500000
-RMRE 12 degree Raptor
-CFE DRCE 4.840 Bore
-CFE Big Chief 10 degree

Ford
-Profiler #205
-Blue Thunder Thor
-IDT Eliminator Series
-Ford C-460
-Ford E-460

Mopar
-NRC Heads (Predator Heads)
-B1 Top Sportsman
-Indy 600-13

Some non conventional heads will be assessed on a per case basis.

Tires:
-29.5x10.5W" slick

Transmission:
-Any automatic or manual transmission allowed with the exception of planetary transmissions
(no Lencos).
-Any converter OK but all shifts must occur manually by the driver. No automatic shifters

Base weight:
-2600# minimum base weight+3# per ci above 300ci to 470ci. Add 2# per ci from 471ci to 632
-Maximum 632ci

Weight adders:
-150# weight adder for clutchless manual transmission
-Ladder bars permitted
-4 links allowed with 25# adder
-Two carbs add 100#
-Sheetmetal intake add 50#
-Wheelie bars add 50#. 60” max length (axle c/l to wheelie bar wheel c/l)
Weight break:
-50# weight break for non forward facing (cowl induction style) hood
-50# weight break for non W rear tire
-50# weight break for stock style rear suspension (diagonal 4 link or 3 link , Torque arms)
-150# weight break for 4.6L/5.4L Modular Engines
-50# nostalgia (1981 and older ) body style/truck
-25# weight break for 2 speed auto transmission
-75# weight break for leaf spring equipped entries- must transmit all power through the eye of the spring

Fuel:
-Gasoline only

If you are building a race car and you are unclear about rules concerning your class, please contact us.

The OSCA reserves the right to impose penalties for rule infractions and on items which do not represent the intent of the class entered.

Rules are subject to change without notice. If in doubt as to rule interpretation please contact us for final ruling.