THIS MAY HELP SOME OF YOU TECHMEN IN THE TECHROOM

 

STOCK BRIGGS

 

AIR FILTER ADAPTER - .250" FROM TOP OF ADAPTER TO CARBURETOR MATING SURFACE -- TOP MUST BE FLAT

THROTTLE SHAFT - .040" MINIMUM FRONT EDGE -- .086" MINIMUM BACK EDGE -- .030" MINIMUM BACKSIDE RECESS -- MUST RETAIN STOCK CONFIGURATION

BUTTERFLY SCREW - .322" MINIMUM LENGTH

AIR HORN - 1.011" MAXIMUM TOP AND BOTTOM

METERING HOLES - .062" MAXIMUM MAIN METERING HOLE -- .028" MAXIMUM IDLE HOLE

FRONT RECESS - .726" MAXIMUM AND MUST BE AS CAST

CARBURETOR BORE - .695" MAXIMUM ENTIRE LENGTH OF BORE

SHORT PICKUP TUBE - .066" MAXIMUM HOLE SIZE

HEAD GASKET - .043" CHECKED IN 4 PLACES ONE ON THE FRONT, REAR AND ONE ON EACH SIDE

HEAD - .011" - .408" - .300" MINIMUM -- BOLT HOLES .3480" MAXIMUM

PISTON POP-UP - .005" MAXIMUM ACROSS THE WRISTPIN AND FRONT OF PISTON

BORE - 2.6025" MAXIMUM

STROKE - 2.427" - 2.444" -- 2.437" +.007" or -.010"

INTAKE VALVE - 30° FACE -- 1.115" MINIMUM DIAMETER -- .035" ON THE EDGE OF THE VALVE (no knife edging allowed)

EXHAUST VALVE - 45° FACE -- .990" MINIMUM DIAMETER

INTAKE SPRING - 1.240" MAXIMUM LENGTH -- .087" MAXIMUM WIRE SIZE

EXHAUST SPRING - 1.500" - 1.300" LENGTH -- .088" - .093" WIRE SIZE -- .625" - .640" INSIDE DIAMETER

RETAINERS - PART # 23184 .50" - .058" THICKNESS -- PART # 555147 .015" - .025" THICKNESS

INTAKE SEAT - 30° SEAT ANGLE -- 1.004" MAXIMUM INSIDE DIAMETER -- .199" - .215" SEAT THICKNESS

EXHAUST SEAT - 45° SEAT ANGLE -- .880" MAXIMUM INSIDE DIAMETER -- .199" - .215" SEAT THICKNESS

FLYWHEEL - 6 lbs. 4 ozs.. MINIMUM

PISTON OLD STYLE - 1.869" MINIMUM LENGTH -- .937" MINIMUM LENGTH TOP OF PISTON TO TOP OF WRIST PIN -- .084" MAXIMUM RING LAND WIDTH

RAPTOR III PISTON - 1.671" MINIMUM LENGTH -- .937" MINIMUM LENGTH TOP OF PISTON TO TOP OF WRIST PIN -- TOP TWO RING LAND WIDTH: .0603" - .0612" -- OIL RING LAND WIDTH: .1020" - .1032"

RINGS OLD STYLE - .105" MINIMUM WIDTH TOP TWO RINGS -- .085" MINIMUM WIDTH OIL RING -- .083" OIL GROOVE MINIMUM

RAPTOR III RINGS - .090" MINIMUM WIDTH TOP TWO RINGS -- .058" + OR -.005" THICKNESS -- .070" OIL RING MINIMUM WIDTH -- .100" + OR - .005" THICKNESS -- IF OIL RING IS BROKEN ALL PIECES OF RING MUST BE IN RING LAND

WRIST PIN OLD STYLE - .290" INSIDE MAXIMUM DIAMETER -- .490" OUTSIDE DIAMETER MAXIMUM

RAPTOR III WRIST PIN - .291" INSIDE MAXIMUM -- .490" OUTSIDE DIAMETER MAXIMUM -- 1.732" + OR - .005" LENGTH

ROD - 3.1233" - 3.1333" LENGHT - ROD MUST BE STOCK

CAM - .770" BASE CIRCLE MAXIMUM -- (SEE 701.16.1 FOR CAM PROFILE )

LIFTER - .982" - 1.005" HEAD DIAMETER -- 1.606" MAXIMUM LENGTH --AFTERMARKET LIFTERS ALLOWED MUST MEET STOCK SPECS

CRANKSHAFT - .990" MINIMUM JOURNAL DIAMETER -- .775" MINIMUM DIAMETER AFTER CLEARANCING FOR BEARING

SILENCER - RLV 8-91 SILENCER -- .1285" NO-GO INTAKE SIDE BAFFLE AND EXIT SIDE BAFFLE

 

BRIGGS SUPER STOCK

 

CARBURETOR - ANY TILLOTSON HL-SERIES CARB. -- .850" MINIMUM VENTURI - .900" MAXIMUM VENTURI -- MUST BE STOCK APPEARING ON THE OUTSIDE

HEAD GASKET - .043" CHECKED IN 4 PLACES ONE ON THE FRONT, REAR AND ONE ON EACH SIDE

HEAD - .011" - .408" - .300" MINIMUM -- BOLT HOLES .3480" MAXIMUM

PISTON POP-UP - .005" MAXIMUM ACROSS THE WRISTPIN AND FRONT OF PISTON

BORE - 2.6025" MAXIMUM

STROKE - 2.427" - 2.444" -- 2.437" +.007" or -.010"

INTAKE VALVE - 30° FACE -- 1.115" MINIMUM DIAMETER -- .035" ON THE EDGE OF THE VALVE (no knife edging allowed)

EXHAUST VALVE - 45° FACE -- .990" MINIMUM DIAMETER

INTAKE SPRING - 1.240" MAXIMUM LENGTH -- .087" MAXIMUM WIRE SIZE

EXHAUST SPRING - 1.500" - 1.300" LENGTH -- .088" - .093" WIRE SIZE -- .625" - .640" INSIDE DIAMETER

RETAINERS - PART # 23184 .50" - .058" THICKNESS -- PART # 555147 .015" - .025" THICKNESS

INTAKE SEAT - 30° SEAT ANGLE -- 1.004" MAXIMUM INSIDE DIAMETER -- .199" - .215" SEAT THICKNESS

EXHAUST SEAT - 45° SEAT ANGLE -- .880" MAXIMUM INSIDE DIAMETER -- .199"
- .215" SEAT THICKNESS

FLYWHEEL - 6 lbs. 4 ozs. MINIMUM

PISTON - .937" TOP OF PISTON TO TOP OF WRIST PIN MINIMUM -- WISECO PISTON OR BURRIS PISTON ALLOWED -- WISECO PISTON MAY BE MACHINED ON TOP AS LONG AS IT MEETS TOP OF PISTON TO WRIST PIN MEASUREMENT

PISTON OLD STYLE - 1.869" MINIMUM LENGTH -- .937" MINIMUM LENGTH TOP OF PISTON TO TOP OF WRIST PIN -- .084" MAXIMUM RING LAND WIDTH

RAPTOR III PISTON - 1.671" MINIMUM LENGTH -- .937" MINIMUM LENGTH TOP OF PISTON TO TOP OF WRIST PIN -- TOP TWO RING LAND WIDTH: .0603" - .0612" -- OIL RING LAND WIDTH: .1020" - .1032"

RINGS OLD STYLE - .105" MINIMUM WIDTH TOP TWO RINGS -- .085" MINIMUM WIDTH OIL RING -- .083" OIL GROOVE MINIMUM

RAPTOR III RINGS - .090" MINIMUM WIDTH TOP TWO RINGS -- .058" + OR -.005" THICKNESS -- .070" OIL RING MINIMUM WIDTH -- .100" + OR - .005" THICKNESS -- IF OIL RING IS BROKEN ALL PIECES OF RING MUST BE IN RING LAND

WRIST PIN OLD STYLE - .290" INSIDE MAXIMUM -- .490" OUTSIDE DIAMETER MAXIMUM

RAPTOR III WRIST PIN - .291" INSIDE MAXIMUM -- .490" OUTSIDE DIAMETER MAXIMUM -- 1.732" + OR - .005" LENGTH

ROD - 3.1233" - 3.1333" LENGHT-- HORSTMAN PN 4951, 4981, HOLLOWAY 4981 NEW OR OLD STYLE, BURRIS BMC 26500 OR A.R.C. 6350 ROD MAY BE USED -- MINOR GRINDING ON THE BACK SIDE TO CLEAR LIFTERS ALLOWED

CAM - .770" BASE CIRCLE MAXIMUM -- (SEE 701.16.1 FOR CAM PROFILE )

LIFTER - .982" - 1.005" HEAD DIAMETER -- 1.606" MAXIMUM LENGTH --AFTERMARKET LIFTERS ALLOWED MUST MEET STOCK SPECS

CRANKSHAFT - .990" MINIMUM JOURNAL DIAMETER -- .775" MINIMUM DIAMETER AFTER CLEARANCING FOR BEARING

SILENCER - RLV 8-91 SILENCER -- .1285" NO-GO INTAKE SIDE BAFFLE AND EXIT SIDE BAFFLE

 

BRIGGS CONTROLLED STOCK

 

AIR FILTER ADAPTER - .250" FROM TOP OF ADAPTER TO CARBURETOR MATING SURFACE -- TOP MUST BE FLAT

CONTROLLED CARBURETOR - .715" MAXIMUM BORE(FULL LENGTH OF BORE], NO MATERIALS ADDED INSIDE OR OUTSIDE, MUST HAVE SOME STOCK RECESS SHOWING, BOTH PICKUP TUBES MUST WORK

SUPER CONTROLLED CARBURETOR - ANY TILLOTSON HL-SERIES CARB. -- .850" MINIMUM VENTURI - .900" MAXIMUM VENTURI -- MUST BE STOCK APPEARING ON THE OUTSIDE

HEAD GASKET - .043" CHECKED IN 4 PLACES ONE ON THE FRONT, REAR AND ONE ON EACH SIDE

HEAD - .400" MINIMUM IN SPARK PLUG AREA-BOLT HOLES -- .3480" MAXIMUM MACHINING OF VALVE AREA ALLOWED MUST NOT HIT THE BACK OF HEAD, MUST NOT BE MACHINED BELOW FLAT CYLINDER PORTION OF HEAD

BORE - 2.6025" MAXIMUM

STROKE - 2.427" - 2.444" -- 2.437" +.007" or -.010"

VALVE BREATHER - AFTERMARKET BREATHER ALLOWED -- CRANKCASE BREATHER ALLOWED

INTAKE VALVE - 30° FACE -- 1.115" MINIMUM DIAMETER -- .035" ON THE EDGE OF THE VALVE (no knife edging allowed)

EXHAUST VALVE - 45° FACE -- .990" MINIMUM DIAMETER

INTAKE SPRING - 1.240" MAXIMUM LENGTH -- .087" MAXIMUM WIRE SIZE

EXHAUST SPRING - 1.500" - 1.300" LENGTH -- .088" - .093" WIRE SIZE -- .625" - .640" INSIDE DIAMETER

RETAINERS - PART # 23184 .50" - .058" THICKNESS -- PART # 555147 .015" - .025" THICKNESS

INTAKE SEAT - 30° SEAT ANGLE -- 1.004" MAXIMUM INSIDE DIAMETER -- .199" - .215" SEAT THICKNESS

EXHAUST SEAT - 45° SEAT ANGLE -- .880" MAXIMUM INSIDE DIAMETER -- .199" - .215" SEAT THICKNESS

FLYWHEEL - 6 lbs. 4 ozs. MINIMUM

SUPER CONTROLLED FLYWHEEL - ONLY FLYWHEELS ALLOWED ARE THE ARC BILLET, J. R. RACE CAR AND UNITED MACHINE AND FAB. FLYWHEELS -- 4 lbs. 12 ozs. MINIMUM

PISTON OLD STYLE - AFTERMARKET PISTON ALLOWED MUST MEET STOCK SPECS -- 1.869" MINIMUM LENGTH -- .937" MINIMUM LENGTH TOP OF PISTON TO TOP OF WRIST PIN -- .084" MAXIMUM RING LAND WIDTH

RAPTOR III PISTON - 1.671" MINIMUM LENGTH -- .937" MINIMUM LENGTH TOP OF PISTON TO TOP OF WRIST PIN -- TOP TWO RING LAND WIDTH .0603" - .0612" -- OIL RING LAND WIDTH .1020" - .1032"

RINGS OLD STYLE - .105" MINIMUM WIDTH TOP TWO RINGS -- .085" MINIMUM WIDTH OIL RING -- .083" OIL GROOVE MINIMUM

RAPTOR III RINGS - .090" MINIMUM WIDTH TOP TWO RINGS -- .058" + OR -.005" THICKNESS -- .070" OIL RING MINIMUM WIDTH -- .100" + OR - .005" THICKNESS -- IF OIL RING IS BROKEN ALL PIECES OF RING MUST BE IN RING LAND

WRIST PIN OLD STYLE - .290" INSIDE MAXIMUM -- .490" OUTSIDE DIAMETER MAXIMUM

RAPTOR III WRIST PIN - .291" INSIDE MAXIMUM -- .490" OUTSIDE DIAMETER MAXIMUM -- 1.732" + OR - .005" LENGTH

ROD - 3.1233" - 3.1333" LENGHT - AFTERMARKET ROD ALLOWED MUST MEET STOCK SPECS.

CAM - MAY BE CENTERED ON BOTH ENDS -- .265" MAXIMUM RUNNING LIFT-CAM GEAR MUST REMAIN AS CAST

LIFTER - OPTIONAL INCLUDING RETAINERS

CRANKSHAFT - .990" MINIMUM JOURNAL DIAMETER -- .775" MINIMUM DIAMETER AFTER CLEARANCING FOR BEARING

SILENCER - RLV 8-91 SILENCER -- .1285" NO-GO INTAKE SIDE BAFFLE AND EXIT SIDE BAFFL

 

BRIGGS LIMITED MODIFIED

 

CARBURETOR - ANY TILLOTSON HL-SERIES CARB. -- .850" MINIMUM VENTURI - .900" MAXIMUM VENTURI -- MUST BE STOCK APPEARING ON THE OUTSIDE

HEAD GASKET - NOT A TECH ITEM

HEAD - .400" MINIMUM IN SPARK PLUG AREA-BOLT HOLES -- .3480" MAXIMUM MACHINING OF VALVE AREA ALLOWED MUST NOT HIT THE BACK OF HEAD, MUST NOT BE MACHINED BELOW FLAT CYLINDER PORTION OF HEAD

BORE - 2.6075" MAXIMUM

STROKE - 2.427" - 2.444" -- 2.437" +.007" or -.010"

VALVE BREATHER - AFTERMARKET BREATHER ALLOWED -- CRANKCASE BREATHER ALLOWED

INTAKE VALVE - 30° FACE -- 1.115" MINIMUM DIAMETER -- .035" ON THE EDGE OF THE VALVE (no knife edging allowed)

EXHAUST VALVE - 45° FACE -- .990" MINIMUM DIAMETER

INTAKE SPRING - NOT A TECH ITEM

EXHAUST SPRING - NOT A TECH ITEM

INTAKE SEAT - 30° SEAT ANGLE -- 1.004" MAXIMUM INSIDE DIAMETER -- .199" - .215" SEAT THICKNESS

EXHAUST SEAT - 45° SEAT ANGLE -- .880" MAXIMUM INSIDE DIAMETER -- .199" - .215" SEAT THICKNESS

FLYWHEEL - ONLY FLYWHEELS ALLOWED ARE THE ARC BILLET, J. R. RACE CAR AND UNITED MACHINE AND FAB. FLYWHEELS -- 4 lbs. 12 ozs. MINIMUM

PISTON - ANY FLAT TOP ALUMINUM PISTON-COATING OF PISTON IS ALLOWED

ROD - ANY ALUMINUM ROD ALLOWED

CAM - TWO PIECE CAM ALLOWED-SIDECOVER MAY BE GROUND TO ALLOW FOR CLEARANCE OF ADJUSTABLE CAMSHAFT BOLTS-NO ROLLER CAMS ALLOWED

LIFTER - OPTIONAL INCLUDING RETAINERS

CRANKSHAFT - .990" MINIMUM JOURNAL DIAMETER -- .775" MINIMUM DIAMETER AFTER CLEARANCING FOR BEARING -- MAY BE CLEARANCED ON COUNTERWEIGHT TO CLEAR CAM-ENTIRE COUNTERWWEIGHT CANNOT BE CLEARANCED

BLOCK - MINOR GRINDING TO CLEARANCE ROD AND LIFTERS ALLOWED

OTHER - THIRD BEARING SUPPORT ALLOWED-GIRDLE STRAP ALLOWED-USE OF SEALANT ON GASKET OR JUST SEALANT ALLOWED ON INTAKE AND EXHAUST SURFACES AND HEAD TO BLOCK

SILENCER - RLV B-91MO SILENCER -- .1285" NO-GO INTAKE SIDE OF BAFFLE -- .2031" DISCHARGE SIDE OF BAFFLE FOR SQUARE HOLE -- .1935" FOR ROUND HOLES

 

OPEN 4-CYCLE

 

ENGINE - ANY 5HP NON-OVERHEAD VALVE, 4-CYCLE SINGLE ENGINE ALLOWED

CARBURETOR - OPEN -- TWO CARBURETORS MAXIMUM

HEAD - OPEN -- NO OVERHEAD CAMS ALLOWED

BORE & STROKE -- OPEN-MAXIMUM DISPLACEMENT SHALL NOT EXCEED 14.5 CUBIC INCHES-FORMULA FOR CHECKING DISPLACEMENT IS B0RE X BORE X .7854 X STROKE = CUBIC INCHES

CAM - NO OVERHEAD CAMSHAFTS

FLYWHEEL - CLEMENTS BILLET OPEN, HORSTMAN, HOLLOWAY, UNITED MACHINE AND FAB. OR ARC BILLET FLYWHEELS ALLOWED -- ALL FLYWHEELS MUST BE AS CAST NO MODIFICATIONS ALLOWED -- NO STOCK FLYWHEELS ALLOWED

SILENCER - RLV B-91MO SILENCER -- .1285" NO-GO INTAKE SIDE OF BAFFLE -- .2031" DISCHARGE SIDE OF BAFFLE FOR SQUARE HOLE -- .1935" FOR ROUND HOLES

 

TECUMSEH STAR

 

CARBURETOR - .900" MAXIMUM

FILTER ADAPTER - CANNOT BE RUN WITHOUT A AIR FILTER

HEAD - .360" AT SPARK PLUG HOLE

HEAD GASKET - .043" MINIMUM

SIDE COVER - 1/8" NPT TO VENT ENGINE ALLOWED

VALVES - STOCK FACTORY VALVES-HEAD DIAMETER NOT A TECH ITEM

INTAKE VALVE SEAT - 30º -- 1.200" MAXIMUM INSIDE DIAMETER

EXHAUST VALVE SEAT - 45º -- 1.025" MAXIMUM INSIDE DIAMETER

VALVE SPRING - 1.700" MAXIMUM LENGTH -- .106" MAXIMUM WIRE SIZE
-- STOCK "STAR" UPPER RETAINER MUST BE USED

VALVE LIFT - .325" MAXIMUM-DURATION -- 265º MAXIMUM WITH SPRINGS INSTALLED .003" OFF OF VALVE SEAT

PISTON - STOCK FACTORY ONLY

PISTON POPUP - .015" MAXIMUM

WRISTPIN - .624" + or - .001" OUTSIDE DIAMETER -- .448" MAXIMUM INSIDE DIAMETER

BORE - 3.348" MAXIMUM

STROKE - 2.522"-2.542"

FLYWHEEL - 7 lbs. 5 ozs. MINIMUM -- NO OFFSET KEYS ALLOWED -- NO PAINTING

 

BRIGGS ANIMAL

 

CLUTCH - TWO OR THREE SHOE CENTRIFUGAL CLUTCH

HEADER PIPE - 24" MAXIMUM

CARBURETOR - PZ MODEL 15 MUST BE AS CAST -- .875" MAX. THROTTLE BORE-VENTURI -- .792" MAX. VERTICAL -- .615" MAX. HORIZONAL -- AIR PICK OFF HOLE .061" MAX. -- SLIDE 1.148" MINIMUM. -- 1.149" CHOKE BORE -- .702" MUST NOT GO PASS STEP IN CARB FROM INTAKE SIDE

INTAKE - 1.740" - 1.760" LENGTH -- .905" - .885" INSIDE DIAMETER
-- .070" MAXIMUM GASKET THICKNESS.

BALL ROCKER - .590" - .610" -- MUST BE STOCK

ROCKER ARMS - 2.875" - 2.885" -- MUST BE STOCK

PUSH RODS - .185" - .190" DIAMETER -- 5.638" - 5.656" LENGTH -- MUST BE STOCK

CYLINDER HEAD PLATE - .055" MAX GASKET THICKNESS -- MUST BE STOCK

CYLINDER HEAD - STOCK PART #558 -- .016" MIN. DEPTH AT SHALLOW PART OF HEAD -- .324" MIN. DEPTH AT FLOOR OF HEAD -- .360" - .340" DEPTH TO TOP OF VALVE SEAT

HEAD GASKET - .049" MIN. THICKNESS CHECKED IN FOUR PLACES -- MUST BE STOCK

INTAKE VALVE - 45° ANGLE -- 1.055" - 1.065" HEAD DIAMETER -- .99" - .119" DEPTH OF DISH -- STOCK FACTORY VALVE

EXHAUST VALVE - 45° ANGLE -- .935" - .945" HEAD DIAMETER -- .084" - .104" DEPTH OF DISH -- STOCK FACTORY VALVE

VALVE SPRINGS - .930" MAXIMUM LENGTH -- .103" - .107" WIRE SIZE
-- .615" - .635" INSIDE DIAMETER -- MUST BE STOCK

VALVE SPRING RETAINERS - .060" - .070" THICKNESS

INTAKE VALVE SEAT - 45° ANGLE -- .966" - .972" INSIDE DIAMETER

EXHAUST VALVE SEAT - 45° ANGLE -- .844" - .850" INSIDE DIAMETER

INTAKE PORT - .918" MAXIMUM

EXHAUST PORT - .980" MAXIMUM

PISTON POP-UP - .005" MAXIMUM ACROSS WRIST PIN

CYLINDER BORE - 2.690" - 2.725"

STROKE - 2.204" MAXIMUM

IGNITION - 3,000 - 6,000 OHMS

FLYWHEEL - 32 - 35 ozs. -- NO PAINTING

CAM -.870 MAXIMUM BASE CIRCLE -- GROUND CAMS LEGAL

VALVE LIFTERS - .820" - .860" HEAD DIAMETER -- 1.515" - 1.525" LENGTH

ROD - 2.419" - 2.429" LENGTH -- .185" MAXIMUM OIL HOLE -- MUST BE STOCK

PISTON - .658" MINIMUM TOP OF WRIST PIN TO TOP OF PISTON -- 1.768" MINIMUM LENGTH - MUST BE STOCK

RINGS - .095" MINIMUM WIDTH -- .059" - .064" MAXIMUM THICKNESS TOP TWO RINGS -- .065" MIN. WIDTH -- .098" - .102" THICKNESS OIL RING --EXPANDER RING MUST BE INSTALLED - MUST BE STOCK

WRISTPIN - .624" - .626" OUTSIDE DIAMETER -- .414" MAXIMUM INSIDE DIAMETER -- 1.901" MINIMUM LENGTH

CRANKSHAFT - 1.094" - 1.100" JOUNAL DIAMETER

SILENCER - RLV 8-91 SILENCER -- .1285" NO-GO INTAKE SIDE BAFFLE AND EXIT SIDE BAFFLE

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