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    B MOD CLASS RULES

 
THE SPIRT AND INTENT OF THESE RULES ARE TO KEEP DOWN THE COST OF RACING A OPENWHEEL MODIFIED
UMP MODIFIED RULES APPLY WITH THE EXCEPTION OF:

 ***ENGINE RULES***
*362 cubic inches max.
*15" of vacuum at 1,000 rpm
 
***BLOCK***
*Cast iron only
*No 400 Blocks
*Max cylinder bore allowed is 4.060"

***Crankshaft***
*Steel or cast iron
*Balancing of engine is permitted.
*No stroking or destroking allowed.
*Stroke must be 3.480"
*No knifing
*50lbs min weight
 

***Rods***
*5.7 rod. I beam rods only
 

***Pistons***
*Dished or flat top 2 or 4 valve relief pistons allowed.
*Pistons must stay flush with or below top of the block.
 

***Camshaft***
*No Roller Cams or Roller Lifters
 

***Cylinder Heads***
*Factory passenger production heads only, no bowtie, or aluminum heads allowed. No angle plugs or performance heads.
*Stock valve stem diameter length.
*Valve sizes limited to OEM production diameter for head used.
*No polishing, porting or match porting anywhere, no milling inside chambers, each chamber must have a 55 cc minimum volume.
*1.5 ratio rockers with stock diameter pushrods.
*3/8 screw in studs or pinned studs allowed, guide plates allowed.
*No shaft mounted rocker arms
*Roller rocker arms allowed
 

***Intake***
*Any cast-iron or cast-aluminum intake
*No tunnel ram or TBI manifolds
 

***Carburetor and Fuel***
*500 CFM 2 barrel Max Holley 4412 or Rochester . Must pass track inspection
*The bottom of the carb can be no larger than (1 11/16") in dia. with stock ventura (1 3/8")
*1" inch adapter plate OR spacer under carburetor allowed.
*Removal of choke plate allowed.
*Manual fuel pump only
*Racing gas or E85 only (no methonal)
 

***Ignition***
*Stock style HEI ignition,
*No mags, or msd boxes
 

 ***Exhaust**
*Headers or manifolds allowed. No 180 degree headers.

     
 ***REAR SUSPENSION


TWO OPTIONS: AFTERMARKET THREE LINK DESIGN OR MULTI-LEAF SPRING DESIGN.
ALL COMPONENTS MUST BE STEEL. ALL MOUNTS AND BRACKETS MUST BE WELDED
OR BOLTED SOLID. PULL BARS ARE ALLOWED.


A). THREE LINK DESIGN REQUIREMENTS: LOWER LINKS MUST BE BE THE SAME LENGHT
WITH 1/2" TOLERANCE MUST USE ONE UPPER CONTROL ARM-TUBE ONLY. (PULL BAR

SPRING OR BISCUIT ASSEMBLY ALLOWED), LOCATED AT TOP CENTER OF REAR END

HOUSING AND REMAIN CENTERED ON HOUSING OVER DRIVE SHAFT. 1" TOLERANCE

MAY USE MINIMUM 19 INCH LONG PANHARD BAR LOCATED BEHIND REAR END HOUSING
OR MINIMUM 19 INCH LONG J-BAR MOUNTED TO A STEEL PINION BRACKET. MEASUREMENTS
ARE FROM CENTER OF HEIM JOINT TO CENTER OF HEIM JOINT. MAY MOUNT REAR SPRING
DIRECTLY OVER AXLE HOUSING OR USE COIL COVER ELIMINATORS (SLIDERS). LOWER SPRING
PERCH OR COIL COVER MOUNT MUST BE WELDED TO REAR END HOUSING. NO BIRDCAGES OR
FLOATING MOUNTS ALLOWED. MUST USE STEEL UPPER WEIGHT JACK IF SPRING ARE MOUNTED
OVER AXLE HOUSING. SHOCK TYPE ELIMINATORS AND COIL SPRING KITS OK.


B). MULTI-LEAF SPRING DESIGN REQUIREMENTS: MUST USE STEEL MULTI-LEAF SPRINGS WITH
ADDITIONAL SUSPENSION COMPONENTS. ONE SHOCK PER WHEEL. ADJUSTABLE ALUMINUM
LOWERING BLOCKS ALLOWED. COIL SPRINGS CAN BE USED WITH LEAF SPRINGS. PULL BAR OK.


 

NO QUICKCHANGE REARENDS ALLOWED
 

**TRANSMISSION**

A). AUTOMATIC: TWO OR THREE SPEED, OEM PRODUCTION CASE WITH A FUNCTIONING STOCK
APPEARING PUMP. MUST HAVE AN APPROVED SCATTER SHIELD CONSTRUCTED OF .125 INCH
BY THREE INCH STEEL, 270 DEGREES AROUND TOP OF FLEX PLATE. SPLINED DRIVE FLANGE COUPLER
WITH INTERNAL PRESSURE RELIEF DEVICE, GATE VALVE OR TORQUE CONVERTER (10 INCH MIN.) ONLY.
HYDRAULIC LINES MAY NOT EXTEND IN TO COCKPIT.
 
B). MANUAL: TWO, THREE OR FOUR SPEED IN OEM PRODUCTION CASE. NO FIVE (OR MORE) SPEEDS
ALLOWED. MUST HAVE WORKING CLUTCH INSIDE EXPLOSION-PROOF STEEL BELL HOUSING WITH ONE
HOLE FOR THROW OUT BEARING LEVER OR HOSE. MUST BE 270 DEGREES AROUND TOP OF CLUTCH AND
FLYWHEEL AREA. MINI-CLUTCH ALLOWED. COMPONENTS MUST ROTATE, CONSISTENT WITH ENGINE RPM,
WHILE CAR IS IN ANY GEAR. NO BERT, BRINN OR FALCON TYPE TRANSMISSIONS ALLOWED.
 
**WHEELS AND TIRES**


IMCA Stamped wheels not required. American Racer tires (G-60 KK704 ) OK


**BODIES**


OPTION A: UMP BODY RULES APPLY
OPTION B. UMP RULES, TOPLESS WITH 12" SPOILER AND 24" X 48" SIDEBOARD ON THE LEFT-REAR DECKING
NOSE FLARE ALLOWED MAX 12" HIGH MOUNTED ON NOSE PIECE ONLY