2. MVS Modified Rules 2021


Limited Late Models are allowed 3035 & 3045 used tires bought at MVS, 10″ steel wheels, stock lower arms in stock location. ABC bodies, 9″ rears only , 602 bought from MVS, 6200 Chip, standard transmissions. All safety equipment required.

2.0 Drive Train

1 Any wet sump engine allowed.

2 Any carburetor allowed.

3 Rear of the engine will be no less than 72” forward of the center line of the rear end.

4 Transmission will have minimum 1 forward and 1 rearward working gear with a neutral.

5 360-degree drive shaft loop required and must be constructed of at least 0.25-inch by 2-inch steel or 1-inch tubing, mounted 6 inches back from both U-joint. Steel drive shafts (minimum 2-inch diameter) and yokes only. Drive shaft must be painted white. No Carbon Fibre.

2.1 Measurements

1 Maximum track width will be 78” measured across the outside of the top of the tires. The front end of may be pushed down to achieve width.

2 Minimum wheelbase will be 107.5” either side.

2.2 Tires Option 1

1 970 tires purchased from Magic Valley Speedway only to be eligible for full purse and year end point payout.

2 Steel wheels 8″ only.


2.3 Suspension

1 Any steel shock non adjustable, no external canisters (Aluminum rod end on the shaft end ok, and an aluminum thread in body cap on the shaft end is ok).

2 Any spring allowed.

3 Front suspension must be unaltered approved OEM and be in stock location, and must be replaceable by stock parts. Tie rod ends and adjustment sleeve may be replaced by a minimum 0.625-inch rod end and steel tube (Heim joints allowed.) Weight jack must be in original center line of spring. Stock passenger car spindles only, no fabricated spindles. Spindles can be ground for brake caliper clearance only.  All calipers must be steel OEM or approved OEM Replacement. Bottom A-frames cannot be altered or moved (exception: can weld shock mount on A-frame; aftermarket ball joints are allowed.) No offset or bearing type lower-control arm bushings. Tube-type upper A-frames allowed and can be moved. Front sway bar can be an aftermarket type. Chain on one side is allowed.

4 Steering box must be steel approved OEM and must remain within original bolt pattern for type of frame used. No rack and pinion allowed, steel steering shafts and knuckles only. In-cockpit steering may be modified to
suit driver’s taste, but must be kept on left side of cockpit. No center steering allowed. Steering columns must be collapsible (U-joints are acceptable.)

5 No devices allowed that would enable driver adjustment to alter wheelbase or for weight jacking while car is in competition.

6 Rear Suspension: No independent rear suspension. All components must be steel. No covers allowed. All trailing arms/link bars must be steel tubing. Rear of frame may be altered to accept leaf or coil springs, and truck arms. Steel coil-over eliminators. Minimum 19-inch long Panhard bar, measured center to center. No cambered rear end housings. Aluminum jack bolts and spring plates allowed.

7 Any approved OEM passenger car type or truck rear end may be used.
No aluminum allowed, except lowering blocks, axle cap and drive flange. A 1-inch inspection hole in center section is recommended. Full steel spool, steel mini spool or welded rear ends only. No open or unlocked rear ends, steel axles only. We will pull rear end out and look for aluminum.
No quick change devices allowed. No cambered rear ends, one piece drive flange only. No electronic or mechanical traction control devices allowed.

8 Aftermarket steel rotors will be allowed. Vented rotors with gas slots or j-hooks on the face will be allowed. NO holes in rotor face. Rotor must be externally round, internally may have scalloping between mounting holes. Rotor hat may be aluminum. Hub must be steel and not drilled, no additional holes.

9- One 12-volt non-adjustable ignition box and coil allowed – must be out of driver’s reach and in a LOCATION THAT TECH CAN GET TO. No additional ignition accessories allowed. The only change that can be made with ignition box is rev-limiter setting, and only one high-end setting is allowed. This setting can be changed through one chip, or an internal setting inside
the box. Electrical: Ignition Box location. LQ4-LQ9-LS525 Engine may have additional coils. Crank trigger ignition allowed.

Racing fuel cells required and must be mounted by at least two solid steel straps 1 1⁄2″ x 1⁄8″ wide around cell. Plus 1″ x 1″ square tubing front, back and bottom of cell. Fuel cells must be enclosed in steel container and must be mounted securely behind rear axle and between the rear tires, no lower than 8 inches off the ground, protected by roll-cage tubing. Protective tubing must cover the rear and extend past both sides of fuel cell. Fuel cells must be protected from bumper down to bottom of cell. Fuel cell must be a minimum of 4 inches ahead of rear bumper and no part of fuel cell shall be lower than protective tubing. Fuel cell vents, including cap vent, must have check valves. Bladders are highly recommended. Fuel cells are limited to 32-gallon maximum capacity. Pick-up must not be underneath fuel cell. A limit of one standard fuel filter allowed between the fuel cell and carburetor. NO Nitrous Oxide. No performance-enhancing fuel additives of any kind.

1- One Carburetor allowed, must be naturally aspirated. Electric fuel pump allowed with oil pressure safety switch.

2- FAST™ EZ-EFI® or FAST™ XFI Sportsman™ System for MVS Modified Series. Part numbers for these systems have been set aside for MVS Modified Series.

3- One FAST™ EZ-EFI® or FAST™ XFI Sportsman™ System may be used. Any engine with carburetor and electric fuel pump MUST have in place a 10-15 lbs oil pressure shut off switch properly wired for the electric fuel pump. FAST™ EZ-EFI® and FAST™ XFI Sportsman™ Systems are internally wired with fuel pump safety shut off.

4- FAST™ EZ-EFI® or FAST™ XFI Sportsman™ System at this time must be purchased from Arce Engines as a complete unit. System will include throttle body, ECM, electrical harness and electric fuel pump.

5- FAST™ EZ-EFI® and FAST™ XFI Sportsman™ System ECM must be mounted in a location that allows easy access for inspection or exchange.

6- At anytime you may be asked to exchange your FAST™ EZ-EFI® or FAST™ XFI Sportsman™ ECM.

7- At NO time shall the FAST™ EZ-EFI® or FAST™ XFI Sportsman™ System wiring harness be altered or changed in any way, shape or form.

8- All FAST™ EZ-EFI® or FAST™ XFI Sportsman™ ECM’s must have the Fuel Injection Racing Association (FIRA) tamper proof seal in place at all times.

9- The FAST™ EZ-EFI® and FAST™ XFI Sportsman™ Systems feature patent pending technology with the most advanced self-tuning control strategy available anywhere today. Simply hook up the necessary wires, answer the basic setup Wizard questions on the included hand-held display and the system tunes itself as you drive. Countless research and development hours were spent on a number of prototype test vehicles to develop a high-quality system truly worthy of the FAST™ brand. Capable of supporting 600-1000 horsepower engines at 60 psi, the FAST™ EZ-EFI® and FAST™ XFI Sportsman™ Tuning Fuel Injection System can be purchased as a complete system, including the ECU, wide-band oxygen sensor, wiring harness, fuel injectors, optional fuel pump kit and other assorted components, including the innovative 4150 Throttle Body from FAST™. The FAST™ 4150 Throttle Body delivers the total package approach for anyone with an existing 4150- type intake manifold. Everything comes with the kit, including appropriate fuel injectors and fuel rails. In addition, it works with the original carb-style throttle linkage and is ready to accept all OEM sensors.

10- This FAST™ EZ-EFI® and FAST™ XFI Sportsman™ System is provided as is, without any guarantees or warranty. In association with the product, MVS Modified Series or Arce Enterprises makes no warranties of any kind, either expressed or implied, including but not limited to warranties of merchantability, fitness for a particular purpose, of title, or of non-infringement of third party rights. Use of the product by a user is at the user’s risk.


2.6 Body

1- Bodies will be at discretion of the tech officials.

2- Spoiler will be 4” tall maximum & 240 sq” maximum. No wider then rear of body. Top 3″ clear.

3- No end caps on spoilers.

4- Rear bumper, steel nerf bars and bodies must not extend beyond width of tires, and  must not contain any sharp edges. Rear bumper no more than 2 inches wider than body on each side. Fuel cells must be protected from bumper down to bottom of cell.

5- Center of bumper, front and rear, must be 18 inches, plus or minus 2 inches, from ground.

2.7 Weight minimum 2500# pre race.

1- Left side weight will be maximum 58% at ANY time.

2- There will be no weight added in front of the spindles, behind the rear end, or in the drivers compartment. Minimum 5# Blocks.

3- All added weight must be in block form and painted white with car # on it.

4- All weights will be measured by Magic Valley Speedway’s scales with driver in driving position with all racing gear either on driver or in driver’s lap.


1- Front clip must be stock or OEM alternative HOWE 5809 or 5810. For questions on front clips call MVS. Must consist of continuous hoops not less than 1.666-inch outside diameter with a wall thickness of at least 0.095-inch. Low carbon, mild steel tubing is recommended Seats, must be frame-mounted in at least six places, with 3/8 minimum bolts. Must consist of a configuration of front and rear hoops connected by tubing on the sides or side hoops. Driver’s head must not protrude outside cage with helmet on and strapped in driver’s seat. Must have minimum of one cross bar in top halo of roll cage. Roll cage must be securely supported and braced. Protection of feet is mandatory. Bar across back of engine with vertical bars and rub rails, or similar protection. No brace bars forward of cage may be higher than stock hood height. Main cage no further forward than engine plate. A minimum of three driver side door bars, at least 11⁄2-inch O.D., must be as parallel with the ground as possible and located perpendicular to the driver so as to provide maximum protection for driver, but without causing undue difficulty in getting into or out of vehicle. The side bars must be welded to the front and rear of the roll cage members. Must have at least one cross door bar, minimum 1 1⁄4-inch O.D., on passenger side of car, either horizontal or angled. (Two is recommended.) Steel door plates, 18-gauge or 0.049-inch minimum thickness metal, must be securely welded to outside of door bars on driver’s side. Plate must cover the area from the top door bar to the bottom door bar and from the rear down post to 5 inches in front of the seat. Must be visible for inspection.


It is required that, at all times, the driver wear a driving suit and gloves of fire-resistant material that effectively covers the entire body. Must meet S.F.I. 3-2A/1 requirements.
It is also recommended that each driver wear fire-proof underwear, fire-resistant shoes and a fire-resistant head shock. Helmets are required and must be Snell – SA2015 Helmet must be worn at all times car is on the track and must accompany vehicle at time of inspection.

Neck restraints MANDATORY. Neck restraints such as a Hans Device is recommended. Some type of neck restraint is mandatory. Roll bar padding required in driver compartment. Steering wheel shaft must be padded. Aluminum high-back seats only, must be bolted in and mounted inside the frame rail and ahead of the rear tire. Bottom of seat can be no lower than the bottom of the frame rail. Bolted in 6 locations, 3/8 bolts. Kill switch required within easy reach of driver clearly marked ‘OFF’ and ‘ON’, in a location that the driver and safety crew can get to it from both sides of the car.
Current test date (2 lbs. minimum) fire extinguisher to be installed in the car within driver’s reach while strapped in. Steel mounts only, no plastic. All cars will be required to have in their pits a minimum of one 5-lbs, halon or dry chemical fire extinguisher. This is to be visible to tech officials and all crew members. All crew members must be made aware of its location, and knowledgeable in the use of the fire extinguisher.

2.10 No titanium, magnesium or carbon fiber products, parts or components allowed. No gun-drilled, tubular or hollow bolts or studs.

2.11 Radios Required. No electronic monitoring computer devices capable of storing or transmitting information except tachometers. Digital gauges are allowed.

2.12 Rules may be adjusted for a more competitive package.

2.13 All cars that qualify slower then .75 behind 3rd quick will start behind the invert.

2.14 SPIN-OUTS Drivers that spin-out must try to continue immediately and not stop the race. Race Control reserves the right to penalize any driver one (1) lap for intentionally stopping a race. • 3-spin rule will be used for any driver that spins on his own.

2.15 ROUGH DRIVING Any driver who is observed causing other drivers to spin will go to the rear of the field. Black flag – Causing other driver to spin, both cars go to the rear of the pack – no gray area. Retaliation!! A driver can be suspended or disqualified from the event (with loss of points and money), or put on probation. A driver will be suspended for running into another car after the checkered flag (on the track or in the pit area.) This rule also applies to lapped cars choosing to re-enter the event or cars seeking retaliation for a previous incidents. RESPECT OTHER DRIVER’S EQUIPMENT! BLACK FLAG: A BLACK FLAG WILL BE GIVEN TO ANY DRIVER THAT IS LOSING A PART ON THEIR RACE CAR, SMOKING/LEAKING BADLY OR TO ASSESS A PENALTY. Lost parts include front or rear bumpers, hoods, body panels, etc. When a black flag is displayed, that driver should immediately report to the hot pit lane for consultation. Decisions on black flags will be made at the discretion of the Series Director or Starter. • Air cleaner come off causing a yellow flag, you go to the back, no yellow no penalty.A

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