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2022 Stafford Speedway Open Modified Rulebook

2022 Stafford Speedway Open Modified Rules

2022 Open Modified Rules Available in PDF Format

The rules herein shall refer to “Stafford Motor Speedway” as SMS. These rules shall refer to “participant” as any owner, driver, crew member, vendor or fan. Upon entry into SMS, all participants agree to be knowledgeable and bound by the contents found in these 2022 Divisional rules and the SMS 2022 General Rules. These rules supersede and replace any contrary rules as posted by any other sanctioning bodies.

Participants are required to register their car number and engine package/cylinder head manufacturer for the Open Modified feature events. Participants can contact the Stafford Motor Speedway Office (860-684-2783) or register online at www.staffordspeedway.com.

A non-refundable registration fee must be submitted.
The minimum age for competition 16 years of age (15 years of age upon prior approval of SMS officials).
A car may not compete in two different divisions during the same race event.
The 80-lap feature will have a draw for qualifying heat starting position, and will use the USAC plus/minus system of handicapping from the qualifying results for the 26 car (maximum) feature starting line-up.
Teams are required to use helmets for each of their five team members (maximum) that are allowed to go over the pit wall for any car service.
There is no fueling or refueling permitted on Pit road / infield.
Drivers must have a suitable HANS, NexGen, Hutchens, or Simpson Hybrid type head and neck restraint device.
All drivers personal safety equipment and restraints must be SFI certified and in-date.
The drivers seat must be a commercially manufactured aluminum containment-type seat. Carbon fiber, or any non-aluminum seat is not permitted.
All SFI certifications must be clearly visible for inspection.
All cars must have a fire suppression system installed.
The interpretation and application of SMS Officials decisions concerning any rules or references to NWMT or MRS rules during and after each event is final and non-appealable.
Please see the SMS 2022 General Rules for additional safety rules and procedures.

TRACK COMMUNICATION FROM RACE CONTROL:

Each cars spotter must be in the designated spotter’s area and monitoring 464.5000 during their qualifying and feature event. Failure to follow the directives from Race Control may result in a penalty for the Driver and the Spotter.

TRANSPONDER SCORING:

All cars must have a working transponder installed 12” rearward of the centerline of the rear axle housing.

My Laps America www.mylaps.com 678-816-4000
Waddell Communications www.waddellcommunications.com 860-573-8821
Racing Electronics www.racingelectronics.com 800-272-7111
Hoosier Tire East www.hoosiertireeast.com 860-646-9646
New England Racing Fuel www.neracingfuel.com 860-679-5555
Gaston Race Enterprises www.gre6.com 860-646-1166
Track Frequency Channel #1 Modified Open 464.5000

 – TIRES
Note-
Teams that have pre-registered may call Hoosier and order their race tires to have set aside for them at the track.
The tire rule will be a Hoosier 1320 compound for left side tires and a Hoosier 1330 compound for right side tires with a quantity of six (6) registered to each team.
These six tires must be purchased at SMS on race night, and will be scanned in to our tire inventory system.
You must complete a Tire registration sheet and submit it to the Tech Center after practice has concluded (prior to the start of qualifying).
You must have four of those six registered tires on your car at all times during all qualifying and feature events.
Competition tire changes are permitted, but you must use only your six registered / inventoried tires.
You are required to notify SMS Officials of your “change tires” positions on the car (right sides, rears, etc…) on your tire registration sheet.
Flat tires/damaged rims must be approved for changing by your SMS pit road official.
Flat tires must be replaced with inventory change tires when those tire positions are flat.
Flat tires must be replaced with “scuffs” when a non-change position tire is flat.
Flat tires may not be replaced with a ‘sticker” tire at any time.

– ELIGIBLE CHASSIS MODELS:
The chassis, interior tin and body must be safe, neat appearing, and acceptable to SMS Officials.
Any NWMT or VMRS legal tour-type modified chassis is permitted.
The interior sheet metal and all body panels must be NWMT or VMRS legal.
An anti-intrusion magnetic steel plate must be installed over the driver side door bars, as described in the NWMT or VMRS rules.
A maximum track width of 84” is permitted, when measured at outer wheel beads.
The wheelbase must be between 104-110 inches.
Front wheel / spindle tethers must be used, and be acceptable to SMS Officials.

The windshield must be driver’s side only, typical flat style, minimum 1/8” polycarbonate material, or the old curved type polycarbonate.
A fully covering hood must be used at all times.
The front spoiler / nose must be a NWMT style nose panel, may be no wider than the front frame rails and may not extend forward beyond the trailing edge of the bumper bar.
The standard Modified type front bumper must be installed at spindle height, and may not extend beyond 31” from upper ball joint.
The standard Modified type rear bumper must be installed at spindle height, and can be no wider than 48”.
Standard Modified type side nerf bars must be installed in accordance with NWMT or VMRS rules.
Belly pans are not permitted.
The rear spoiler mounting point (maximum height of rear quarter panels and back tail light panel) may be no higher than 36”.
The rear spoiler may be a maximum of 8” tall and a maximum of 48” long clear ¼” thick polycarbonate. It must be centered between the quarter panels.
The roof must be a minimum of 40” measured from the ground to the center line of the roof, measured 6” behind the top windshield bed. The roof may have a maximum height of 43”.
Carbon fiber or titanium chassis, suspension, or body components are not permitted.

You may not compete without the roof, windshield, hood, air filter or mufflers in place. Additionally, the bumpers and all nerf bars must be adequately secured to the chassis at all times. SMS Officials will pass judgment on any body / bumper / nerf bar damage prior to continuing an event. Their decisions are final and non-appealable.

– FUEL:
Sunoco Standard Purple 110 or Sunoco Supreme Blue 112 leaded fuel must be used.
Sunoco Fuel is available at SMS.
SMS will sample your fuel as part of our technical inspection process.
Blending or mixing of any fuel type or additives is not permitted.

– FUEL CELL:
The fuel cell and its installation must be acceptable to SMS Officials.
A rubber bladder fuel cell must be used.
The fuel cell must be a maximum of 24 gallon capacity.
The fuel cell may be a maximum of 5 years old.
The top plate must have a fully functioning roll-over check valve.
A minimum ground clearance of 5” must be maintained.

– SUSPENSION:
All front and rear suspension components and their installation must be acceptable to SMS Officials.
Standard / Typical Modified type suspension components must be used.
Bump stops, coil bind and/ or travel limiters of any kind are not permitted.
The suspension must compress and extend beyond the normal travel of the cars suspension, without any limit to its movement other than by the springs natural resistance.
Cockpit remote chassis adjusters are not permitted.

Front Suspension:
The suspension and coil springs at all four (4) wheels must be active and permit suspension movement in compression and rebound.
All downward chassis movement while the race vehicle is in competition must be limited only by the normal increasing stiffness of the springs or the bottoming of the chassis against the race track, whichever occurs first.
Any device or procedure that in the judgment of SMS Officials attempts to detract from or compromise the above will not be permitted, including coil-bind or travel limiting.
Any type of chassis travel limiter, used in compression or rebound, will not be permitted. If it looks like you’re compressing the spring completely, or achieving any type of travel limit, you can’t run it.
With your car on our 1″ tall suspension inspection pads, your car must travel down and have the front nose panel touch the ground when the front suspension is compressed, without creating coil bind or travel limiting of any kind. Again: If it looks like you’re compressing the spring completely, or achieving any type of travel limit, you can’t run it.
A maximum of ONE full (360 degree) non-adjustable spring rubber in the right front and each rear coil over spring is permitted.
The spring rubber must be made of rubber, urethane or silicone, with no solid material inside it. A left front spring rubber is not permitted.
Shock/Coil over boots or bags are not permitted.

Coil Over Springs:
Coil over springs must be manufactured from one solid piece of heavy-duty magnetic round steel  and must be constructed with both coil ends closed and ground.
One inactive coil on each end of the coil spring is permitted.
Only one (1) spring per wheel will be permitted.
All active coils of the spring must have the same coil spacing.
Progressive or digressive rate springs will not be permitted.
Front coil must be a minimum of 6” in free height and be a minimum of 250 lb. per inch in rate.

– SPINDLES / HUBS:
Spindles / Hubs and related components must be acceptable to SMS Officials.
Steel spindles only.
Aluminum or magnesium hubs may be used.
Hubs that require oil as lubricant are not permitted.
Wheel bearings must be tapered cylindrical magnetic steel (Timken type) bearings.

– SHOCKS:
Shocks and their installation must be acceptable to SMS Officials.
Non Adjustable or Single Adjustable Shocks must be used.
One shock per wheel permitted.
Remote or External Reservoir Shocks are not permitted.
Remote adjustable shocks are not permitted.
Shock bump stops (internal or external) are not permitted.

– BRAKES:
All brake system components and their installation must acceptable to SMS Officials.
The brake pedal must operate all 4 wheels.
Titanium, ceramic or carbon fiber components are not permitted.
A conventional “Modified” type brake system must be used.
One brake bias control valve is permitted.
Brake enhancing devices of any kind are not permitted.

– REAR / GEAR:
An 8” or 10” diameter ring gear Quick Change rear with a 4.86 maximum ratio final drive gear must be used.
A “straight” or non-quick change rear is not permitted.

– DRIVE TRAIN:
All drivetrain components and their installation must be acceptable to SMS Officials.
Any traction altering or enhancing device of any kind is not permitted.

DRIVESHAFT-
The driveshaft, u-joints and yoke must be magnetic steel.
The driveshaft must be a minimum of 2” in diameter.

SHIFTER-
The shifter and all of its components must be made of steel or aluminum.
Forward and reverse gears must be operational via the cockpit shifter.

TRANSMISSION-
The transmission, its related components and its installation must be acceptable to SMS Officials.
A GM 3 or 4 speed transmission, a Richmond part # RIC70200, or a Jerico part #2SP or NWMT legal Jerico transmission must be used.
The transmission must weigh a minimum of 50 lbs (dry weight).
The gearing must be 1:1 on final drive, and nothing lower than a 1:15 on any other gear.
The transmission must have a working reverse gear.
GM-
Stock GM cast iron or aluminum case 3 or 4 speed may be used.
The GM transmission must have a maximum of 4 and a minimum of 2 forward gears in working order.
Richmond part # RIC70200-
The Richmond transmission must be used, as manufactured, with no modifications permitted.
Jerico part # JEP 2SP- / NWMT Type-
The Jerico transmission must be used, as manufactured, with no modifications permitted.

– CLUTCH
The clutch assembly and its installation must be acceptable to SMS Officials.
A conventional 1, 2, or 3 disc clutch must be used.
Clutch discs must be magnetic steel.
The pressure plate may be steel or aluminum.
The clutch must be a minimum of  5-1/2” diameter.
The flywheel and pressure plate must be bolted to the crank flange of the engine
A Ram coupler or direct drive type assemblies are not permitted.
Carbon fiber, titanium, or composite materials are not permitted.

– REAR END ASSEMBLY
The rear end, its associated components, and its installation must be acceptable to SMS Officials.
A quick change rear must be used.
An 8” or 10” diameter ring gear must be used.
A standard type spool must be used.
Any type of ratchet, open, or slipping chuck is not permitted.
All components must be steel or aluminum (titanium or carbon fiber is not permitted).
A rear spur gear quick change must be used (non-quick change or straight rear is not permitted).

– WHEELS
Wheels must be magnetic steel.
Wheels may be a maximum of 15” wide.
Lugs and lug nuts must be magnetic steel.

– CAR WEIGHT
SMS reserves the right to modify car weight requirements as deemed necessary for competition.

– POST-RACE MINIMUM WEIGHT
The post-race (qualifying or feature) minimum total weight is detailed below.
You will be penalized one finishing position per pound that you are under on the total minimum post-race weight.
The maximum left side weight percentage is detailed below. There is no tolerance on maximum left side total.

* 18° Engines must weigh a minimum of 2,515 pounds / maximum 56% left post-race.
* 23° Engines must weigh a minimum of 2,515 pounds / maximum 56% left post-race.
* Dart Spec Engine must weigh a minimum of 2,515 pounds / maximum 56% left post-race.
* Steel head engines must weigh a minimum of 2,515 pounds / maximum 56% left post-race.
* NWMT Spec engines must weigh a minimum of 2,550 pounds / maximum 55% post-race.
* 23° All Pro cylinder head engines must weigh a minimum of 2,550 pounds / maximum 56% left post-race.
* Steel head engines that have compression ratio over 12:1 (maximum of 13:1) must weigh a minimum of 2,565 pounds / 56% left post-race.

*Amendment 6/10/21*
Due to recent parts availability issues, any 23 degree steel head or aluminum head engine (except the All-Pro cylinder head) may run the approved Tri-Y headers, and add 35 lbs. to the post-race weight, new total being 2,550 lbs.
We will review the parts availability issues and reserve the right to change and/or edit this as needed.

 – ENGINES
SMS reserves the right to modify engine rules and weight requirements, as deemed necessary for competition.
You must declare your engine and cylinder head package when registering for the event.
18 degree, 23 degree, 23 degree All-Pro, Dart Spec, NWMT Spec, or Tour-type steel head engines must be used.
Any other engine package must receive approval prior to competition.
See detailed engine package rules below.

CARBURETOR:
Please see section A2 (carburetor rule) at the end of this rulebook
Boosters in all carburetors must be safety wired with minimum .025 wire.
Two (2) throttle return springs must be installed.
See each engine package rule for carburetor details.

IGNITION: One MSD 6ALN ignition box is permitted, mounted on right side of drivers compartment. A 6 pin male/female connector is mandatory.
Crank trigger ignition is permitted, without an ignition module installed in the distributor.

EXHAUST: NWMT legal mufflers, Kooks MRS 350 or Flowrite MRS 351 unaltered mufflers must be used.
Merge collectors are not permitted.
See each engine package rule for header details.

NWMT SPEC ENGINE OPTION:
The current NWMT 364ci /10.5:1 cr Spec Engine rules shall be followed.
All engines shall remain in NWMT legal configuration, from carburetor to headers.
All engine parts shall bear the NWMT encrypted square-dot code pattern.
The NWMT engine package shall require a post-race minimum weight of 2550 lbs, with a 55% left side maximum weight.
SMS reserves the right to modify the weight requirements of this engine package, at their discretion, to ensure fairness of competition.

23° ALUMINUM HEAD OPTION:
The previous NWMT and MRS 23 degree rules shall be followed.
The following 23 degree cylinder heads are the only cylinder heads permitted:
Air Flow Research AFR 215
All Pro AP 227
Brodix 3941075
Chevrolet 10051101
Dodge W-7 Casting P4532442B,
Dodge P5249958 (Unported)
Dodge P5249850 (CNC ported)
Ford M-6049-C302 with 4 Degree Valve Cant
Pontiac 10033867
Please see section A1 (cylinder head rule) at the end of this rulebook
Any steel GM or aftermarket block is permitted.
Lightening of the block is not permitted (weight penalty may be assessed).
Any intake manifold is permitted.
Any ignition system is permitted.
Connecting rods must be steel.
Maximum compression ratio for this package is 12 to 1.
Maximum valve angle is 21 degrees.
One 390 cfm Holley open booster carb, per VMRS rules must be used.
Please see section A2 (carburetor) at the end of this rulebook.
A single (1) carb spacer, with a maximum height of 1” is permitted.
Kooks MRS 350 or Flowrite MRS 351 unaltered mufflers must be used.
Headers may be standard, or stepped (1-3/4 to 1-7/8 only.)
Maximum retail price for headers is $950/pair.
Merge collectors are not permitted.
Tri-Y headers are not permitted to be used with this engine package.

18° ALUMINUM HEAD OPTION:
Engine specs per 18 degree rules (sec 3, ref A1).
Please see section A1 (cylinder head rule) at the end of this rulebook.
Carburetor- NASCAR legal square booster 390 cfm Holley, or MRS legal 390 cfm Holley.
The NASCAR legal 390 bridged booster may be shortened to .500 in height.
SB2 type cylinder heads are not permitted.
A single (1) carb spacer, with a maximum height of 2” is permitted.
Maximum compression ratio for this package is 12 to 1.
Kooks MRS 350 or Flowrite MRS 351 unaltered mufflers must be used.
Headers may be standard, or stepped (1-3/4 to 1-7/8 only.)
Maximum retail price for headers is $950/pair.
Merge collectors are not permitted.
The MRS Spec Tri-Y header, the Beyea Part# AM TY18S2 Tri-Y header, or similar Tri-Y header may be used on the 18° engines.

DART ALUMINUM HEAD OPTION:
Cylinder head part number # 11510020PF, valve job and combustion chamber work are the only modifications permitted.
Intake part number RHS 12902, as manufactured.
Stainless Steel Valves, 11/32” valve stem diameter, 2.055 Intake Max / 1.625 Exhaust Max
Flat surface cutting permitted.
Maximum compression ratio for this package is 12 to1.
Any Holley 4150 series HP 4 barrel carb permitted.
A single (1) carb spacer, with a maximum height of 2” is permitted.
Kooks MRS 350 or Flowrite MRS 351 unaltered mufflers must be used.
Headers may be standard, or stepped (1-3/4 to 1-7/8 only.)
Maximum retail price for headers is $950/pair.
Merge collectors are not permitted.

STEEL HEAD OPTION:
Cast iron GM Bow-Tie part# 140-11034, part# 1248-0034, part# 1248-0053 or DART part# 105-100-20PF must be used.
STOCK steel heads may use any Holley 4 barrel carb.
Any steel stock or after-market GM block may be used.
Lightening of the engine block is not permitted.
Engine blocks that have been lightened will be assessed a weight penalty.
Any intake is permitted.
Any ignition is permitted.
Connecting rods must be steel.
Maximum lift (camshaft) for steel head engine is .725 at zero lash.
A single (1) aluminum carb spacer, with a maximum height of 1” is permitted.
Kooks MRS 350 or Flowrite MRS 351 unaltered mufflers must be used.
Headers may be standard, or stepped (1-3/4 to 1-7/8 only.)
Maximum retail price for headers is $950/pair.
Merge collectors are not permitted.
Maximum compression for any steel head is 12 to 1.
Steel Head engines with compression ratio over 12:1 (maximum of 13:1) will have a 50 pound weight penalty.
See Post-Race minimum weight above.

STEEL HEAD / CARBURETOR OPTION:
Cast iron GM Bow-Tie part# 140-11034, part# 1248-0034, part# 1248-0053 and DART part# 105-100-20PF
Stock heads…see head rule. May use Any Holley 4-barrel carburetor.
Any cast iron heads that exceed head rule must use 390 cfm Holley open-booster carburetor.
All 390 carburetors will be checked with inspection gauges.

DART STEEL HEAD RULE:
A.
Must use part # 105-100-20 PF.
Carb must be a Holley 4150, may use aftermarket metering blocks.
Please see section A2 (carburetor) at the end of this rulebook.
B.
The Dart Head Part #. 105-100-20PF must remain in box stock condition with the following exceptions:
1) Combustion chamber may be polished.
2) Heads may be resurfaced as required.
3) Valve size- 2.055 max on Intake, 1.625 max on exhaust.
The maximum valve angle permitted is 21°.
4) Intake Port Work / ( Stage 1 ):
Intake Port may be gasket matched to a max of 1.380 in width 2.380 in height. The Intake port may also be worked from the intake flange of the head inward as follows:
Port Floor 1.700 in from flange max depth.
Push Rod side of port 1.700 in from flange max depth.
Roof of port 1.700 in from flange max depth.
Divider wall side of port .750 in from flange max depth.
Port width at push rod pinch area will be 1.120 max width measured from the un-ported area of the divider wall.
Any work beyond the max limit will be deemed illegal. No material shall be added to any part of the head including, but not limited to the roof and the push rod area.
5) Exhaust port must remain stock as cast, with the exception being you may work the area below the bottom cut of the valve seat into the bowl area 1” (1 inch) 360° max/limit. (Example: bottom cut of 45°seat in toward valve guide 1″ (1 inch) 360°.) The roof and side walls of the exhaust port from exhaust mounting flange of head .950 minimum in towards the short side radius must remain untouched as cast. Max and minimum being the limit. Any work done outside the limit will be deemed illegal.
C. Any intake may be used with these heads. Normal intake porting is allowed, but intake must remain in its original exterior dimensions.
D. Steel type stock replacement valve seats only when required.
E. Work allowed on the valve seat, ledge or factory undercut area of Intake Bowl is as follows: No angle cuts, metal removal, or enlarging of ports allowed below the top of the valve seat that would allow the gauge to drop below the seats as follows:
.250 + 1/32” from top of the valve seat on intake of DART heads.
F. Measurements will be strictly enforced by the use of SMS Go/No Go inspection gauge.
G. Intake 1.875” OD of gauge on intake.
H. Stainless steel valves only.
I. 11/32 Valve stems

STOCK STEEL HEAD RULE:
May run any Holley 4 barrel carburetor with this option-
A.
Stock cast iron GM Bow Tie heads will be subject to a runner volume test. Runner volume 190 cc maximum.
B. Any intake may be used with these heads. Normal intake porting is allowed but intake must remain in its original exterior dimensions.
C. Heads may be milled: angled or straight cut allowed on both block and intake surfaces.
D. All manufacturers’ identification numbers are to be visible and unaltered on cast iron heads.
E. Combustion chambers may be polished; cc’d, but must maintain stock shape and appearance.
F. Any intake and exhaust valves allowed. 2.055 maximum intake valve head diameter, 1.625 maximum exhaust valve head diameter.
G. Flashing may be removed from heads anywhere except in the intake and exhaust runners and ports.
H. No removal or smoothing of metal will be allowed in the intake or exhaust runners.
I. Ports and runners cannot be reworked in any way to increase flow.
J. Reworking the heads in any way to match intake and exhaust manifolds will not be allowed.
K. Any valve guides. Valve guides must be left at stock height in the intake and exhaust ports and no grinding or smoothing in this area will be allowed.
L. Work allowed on the valve seat, ledge or factory undercut area of the heads is as follows: angle cuts, metal removal, or enlarging of the ports allowed below the top of the valve seat that would allow the gauge to drop below the seats as follows:
1)½” + 1/32” from top of the valve seat on intake of Chevy Bow Tie heads.
2)½” + 1/32” from top of the valve seat to the top of the gauge on exhaust of Bow Tie heads.
M. Measurements will be strictly enforced by the use of SMS Go/NoGo inspection gauge.
N. Exhaust: 1.350” OD of the gauge on exhaust.
O. Intake 1.718” OD of gauge on intake.
P. Any Cylinder head that you want to race with must be pre-approved in order to run.

A1.  Aluminum Cylinder Head-
The approved cylinder heads must be acceptable to SMS Officials and meet the following requirements:
Spacing between valves is 1.935 inches, center to center, for the General Motors cylinder heads, 1.936 inches, center to center, for the Dodge W-8 cylinder heads, and 1.900 inches, center to center, for the Ford cylinder heads.
Valves must remain in the manufactured location in relation to the cylinder bore centerline.
Only steel or titanium valves are permitted.
Only magnetic steel valve springs are permitted.
There are no restrictions on the valve size.
Internal polishing and porting will be permitted.
Spark plug holes must remain in the manufactured location.
Angle cutting of the cylinder head to the engine block mating surface will not be permitted.
Milling of the heads will be permitted, but not to exceed 0.175 inch.
Valve angle must remain within two degrees of the approved cylinder heads manufacturing.

A2. Carburetor-
Only Holley replacement or service parts can be used in any carburetor rework.
Carburetors and/or carburetor components machined from billet materials will not be permitted.
All carburetor modifications must be acceptable to SMS Officials.

390 “open” carb specs:
Booster OD- .617
Bridge may be removed- .450
Length- .500
Installed height- .467
No tapering of ID or OD of booster.
Booster leg must remain unaltered.
Throttle shafts, unaltered- .197

Holley 4150HP Series: The Holley 4150HP list number 80507, and Holley 4150 list number 6895, four (4) barrel carburetors with a maximum venturi size of 1-1/16 inches and a maximum throttle bore size of 1-7/16 inches are approved for use where indicated.
-Main Body:
The only carburetor main body that will be permitted for the Holley 4150HP Series will be the Holley main body with casting number 6R-7879B.
The Holley casting numbers must remain legible on the top of the main body.
Main bodies must remain as manufactured.
-Carburetor Boosters:
The Holley booster part number 45R-107-1, with the casting number 45R-312 are the only boosters that will be permitted. A bonding agent may be used to assist in adhering the carburetor booster to the carburetor main body, but it must not extend past the carburetor main body booster mounting hole into the carburetor venturis.
Each carburetor booster must be secured by a steel wire not less than 0.025 inch in diameter.
-Venturis:
The maximum diameter of the venturis must not exceed 1.064 inches.
Altering or reshaping of the venturi in any manner will not be permitted.
-Throttle Body (base plate):
The only throttle bodies permitted will be the Holley throttle bodies with casting numbers 12R-6236B or 12R11524B.
The carburetor throttle body must not be larger than 1.438 inches.
The throttle body must be straight without taper from top to bottom.
-Throttle Plates (butterflies):
The throttle plates (butterflies) must be magnetic steel and must not be thinned or tapered.
Idle holes may be drilled in the throttle plates.
-Throttle Shafts:
Holley magnetic steel throttle shafts must be used.
Shafts must remain standard production size and must not be thinned or cut in any manner.
The combined thickness of the throttle shaft and the throttle plate (butterflies) must not be less than 0.197 inch.
-Carburetor Metering Blocks:
Only Holley metering blocks will be permitted.

Alterations that, in the judgment of SMS Officials, were made to allow additional air to be picked up below the opening of the venturi, such as but not limited to, altered gaskets, throttle bodies, drilling or machining holes into the carburetor will not be permitted.

Rules Disclaimer:
The rules and/or regulations set forth herein are designed to provide for the orderly conduct of racing events and to establish minimum acceptable requirements for such events.
These rules shall govern the condition of all events, and, by participating in these events, all participants are deemed to have complied with these rules.
No expressed or implied warranty of safety shall result from the publication of or compliance with these rules and/or regulations.
They are intended as a guide for the conduct of the sport and are in no way a guarantee against injury or death to a participant, spectator, or official.
Stafford Motor Speedway Management / officials shall be empowered to permit reasonable and appropriate deviation from any of the specifications herein or impose any further restrictions that in their opinion do not alter the minimum acceptable requirements.
No expressed or implied warranty of safety shall result from such alterations of specifications.
On occasions when situations arise that are not covered by written rules, Stafford Motor Speedway Officials may put special rulings into effect.
Once such rulings are acted upon, they may become an act of policy and may be added to the existing rules and procedures.
Any interpretation or deviation of these rules is left to the discretion of Stafford Motor Speedway officials. Their decision is final and unappealable.