March 22, 2017

V-8 Thunder Stocks

Hendry County Motorsports Park 2016 V-8 Thunder Stock Rules


  • The Hendry County Motorsports Park officials may inspect any car and equipment at anytime for compliance.  All cars must have an extensive safety inspection each season before they race. In addition, there will be a routine safety inspection every week before the racing event.
  • All required safety equipment and apparel must be in use while the car is on the track.
  • Racing helmet with minimum Snell 95 rating.  Neck brace or head and neck restraint recommended
  • Fire suit with SFI minimum rating of “I”.  No holes or torn fire suits allowed.
  • Fire resistant gloves, shoes, and socks must be worn at all times when car is on track.
  • A minimum four-point roll cage.  Must be steel pipe or tubing, a minimum of 1 1/2” (1.50”) outside diameter with minimum of 0.095” wall thickness. No square tubing or galvanized pipe allowed. No exceptions. Roll bar padding recommended around driver.  Unibody cars may be tied together not to exceed 10 inches “overlap at joint front and rear.”  No double frame.  All rear and front roll cage tubes must sit on original frame.  Front and rear down bars allowed.
  • An engine kill switch must be mounted in the window net area and easily accessible by the driver and from outside of the car.  The switch must be clearly marked “Ignition Switch” and show On and Off position.
  • All cars must have a fire extinguisher, minimum 2 lbs. securely mounted within easy reach of the driver.
  • A single quick release 5 point harness (minimum 3” belts) dated 2012 or newer is required in all vehicles.  All required belts must be in use anytime the car is on the track.  Racing harness must be attached to the roll cage.
  • Window nets are required on the driver’s side of the car and must be securely mounted.  Nets must latch at the top and be operational from inside and outside of car.  Drivers must be able to exit both sides of the car.
  • Aluminum racing seats are mandatory. Containment seats highly recommended
  • Drive shaft must be painted white and include the car number.  Drive shaft loop will be a 5” diameter steel loop.  1” wide and ¼” thick.  It must be securely mounted to the frame 12” from the front universal.  Must have one on rear drive shaft.
  • Battery shall be secured to frame of car and must be encased.
  • All lead ballast must be painted with car number and secured with one ½” bolt per 50 lbs.  It is your responsibility to make sure your ballast stays in your car for everyone’s safety.  Penalty weights must be painted red or orange.  If weight falls off of your car on the track at any time you are immediately disqualified from the event.
  • Throttle toe strap is mandatory.  Throttle linkage must have two return springs.
  • All cars must have front and rear hook ups for towing.
  • All cars must have a radiator over flow can.  Water only for coolant.
  • All standard transmissions must have a scatter shield.
  • If it’s not stated in the rules it does not mean it is approved.  Please consult with tech-man for approval.  All tech decisions are final.  The track reserves the right to add weight to any driver in the fairness of competition.
  • You need to understand all safety requirements. Track Management as well as the Tech Man reserves the right to disqualify any car and/or driver that does not comply with all safety requirements.  Competition will not and cannot come before safety.


  • Any 1970 or newer American made production 2 or 4 door sedan. Must remain stock for year, make and model unless stated. The minimum wheelbase allowed is 101” (1” tolerance) (centerline of front wheels to centerline of rear wheels.  (This cannot be altered).  Weight 3200 lbs. with original driver after completion of the race. Cars with stock bodies only may weigh 3,100 lbs.
  • No subcompact cars.  No foreign convertibles, trucks, four wheel drive or front wheel drive cars allowed.
  • No chopping, shortening, or channeling.  Both sides must be the same.
  • In case a frame issue comes up from a wreck, get with tech to see how or if the chassis is capable to be put back to be legal.


  • Completely stock for year make and model.  Doors may be replaced with 18 gauge (.047”) steel or (.040) aluminum. Stock body panels or self-made body panels, aluminum or steel must be as close to stock appearing as possible. Must have body lines
  • Car body must be strictly stock.  No modifications or alterations of any kind unless outlined below. No flaring of bodies.
  • Removal of interior parts which can be removed with hand tools are okay.  No cutting of any panels allowed.  Any interior part that is flammable must be removed.
  • Left and right passenger doors may be gutted for roll bars.  Minimum of 4 bars on driver’s side.  Three bars on passenger side.
  • All exterior trim must be removed.
  • Hood must have hood pins in front, hinges or pins at rear. Hood must close in original stock position.
  • Inner fender panels may be removed.
  • Complete stock floor pan must be retained.  No sheet metal floor pan.  In case of repairing damaged, rusting or rotted floor pan you must use same gauge or heavier of stock floor pan.
  • Fenders may be trimmed for tire clearance.
  • Stock factory brake pedal must be mounted in original factory stock location.
  • The window channel on the front doors of a sedan style body may be removed.  All other window posts must remain as placed by manufacturer in original location, but may be self-made aluminum or steel.       Disqualification for window posts is not automatic. A weight penalty may be added at the track’s discretion prior to the start of the event.
  • All glass and plastic must be removed.  Plastic stock appearing noses only.  No slope or late model style noses.
  • No side windows of any kind. A weight penalty for side windows is at the track’s discretion.
  • Factory spoilers and side skirts are okay. 6” by 60” maximum aftermarket spoiler.  No side spoilers.  Aftermarket side skirts must meet ride height rule.
  • Bumpers may be steel tubing with no sharp edges, corners must be rounded.  Pipe may not be larger than 1 3/4” by .095 thickness.
  • Steel tubing may be used to brace or protect radiator.  One hoop bar over radiator attached to frame horns may be used.  It may be braced with bars angled to frame horns.
  • Windshield bars ½ round tube maximum 6’’ apart to at least half way of drivers side
  • Inner skin of hood and trunk lid may be gutted.
  • Floor of trunk area may be removed from center of rear-end back.
  • May have rub rails (one per side only) made of 1” round or square tubing, ends must be capped at a 45 degree angle.
  • Trunk and fuel cell area must be tightly sealed from the driver compartment.
  • Rear spoiler, from deck height to top of spoiler must not exceed 6” at any angle. May be decked from trunk to behind driver’s seat, but must be open underneath for inspection.
  • Window net must unhook from the top.
  • Battery must be self-contained and securely mounted in battery tray.
  • No two-way radios. No audible communication devices except receivers.
  • Dashboards are required and may be made of steel or aluminum.
  • All pedals must remain in stock location, with the exceptions of clutch pedal and slave cylinder on cars converted to standard transmission that had no manual clutch.
  • Stock OEM body parts are allowed, may be stock replacement aftermarket.
  • Stock steel roofs only. Roofs may not be fiberglass or aluminum.
  • Trunk lids must be stock appearing.
  • All sheet metal, roof height, firewalls, floor pans, and body mounts must remain in stock location and dimensions.

Chassis and Suspension

  • Aftermarket stock mount springs are okay.  No composite leaf springs.  Rear springs must fit in stock location and buckets.  Rear coil spring bucket spacers ok, must be same height. Leaf springs may run longer or shorter shackles than stock, must be the same length, non-adjustable. Ride height 5”.  One shock per wheel.  Shocks must be in factory stock location only.  No coil overs.
  • Car must sit level with a minimum height of 5” of clearance from frame to ground including the nose piece. This will be checked on a regular basis. After market side skirts must meet ride height rule. The top 3 in each heat and after qualifying will be checked. If your car is found to be low, you will be required to fix your ride height and start in the rear of the feature events.
  • May use non-threaded, non-adjustable spring buckets in front only.  Must be same height.  No tolerance.
  • Camber may be adjusted with any length bolts. Factory replacement offset upper control arm shaft ok.
  • Sway bar may be removed.  If the sway bar remains on car it must be stock for make and model.  No heating or tweaking.  No adjusting or spacing of bar.
  • Stock replacement shocks: may shim shocks lower or higher 1’’on frame side only, in original mount rear shocks only steel body, non-adjustable factory stock locations. Must be only, must be steel, and factory mounting.  Can run 50/50 steel body racing shock.  Split valve shocks are ok.  No adjustable shocks.
  • Shock claimer rule, $60 per shock and must forfeit own shocks. Driver claiming shock(s) must have finished in top 5 and be on the lead lap. Procedure for shock claimer is the same as the protest procedure listed at the end of the rules. (You can only claim the shocks of a car that finishes in front of you.)
  • Steering components must be stock for make, year, and model of car.  Quick release allowed.  Quick steer ok.  Aftermarket power steering pump allowed. No 6:1 steering boxes.
  • Factory replacement offset upper control arm shaft ok.
  • All upper and lower ball joints must be stock size and length.


  • Stock for make and model.  GM350, Chrysler360, Ford351 MAX.  Metric cars will be allowed 350 cubic inches.  Engine location in stock position for make and model. After market motor mounts o.k.
  • Engines must remain strictly stock as produced by manufacturer.  No modifications of any kind unless outlined herein.
  • No high performance engine of any kind.  No high performance parts of any kind.  No air boxes.
  • Heads 70cc minimum. 56cc head is acceptable for Ford Engine only with a 50 pound weight penalty.
  • 3 angle valve job is okay.  Final cut no greater than 75 degrees. No 2.02 head. Maximum valve size 194/150.
  • Bronze guides okay.
  • 270” O.D. maximum valve spring diameter.  OEM replacement valve spring retainers are okay.  No light weight, aluminum, or titanium.
  • Stainless OEM stock replacement valves.  Neck downs and swirl polished are okay.
  • Screw in studs, guide plates, and polylocks are okay.
  • No grinding on any engine part or component.
  • Maximum overbore allowed is .060 + .010 for clearance.
  • Optional: pulleys, oil pan and engine fasteners.  Aftermarket or racing valve covers and oil pans are permitted.  Aftermarket pulleys permitted.  No fluid dampeners or no high performance fuel pumps.       Stock type fuel pump only.       No electric. For example, 6900 carter pump ok. Must be pump gas or race fuel. No E-85 or Propeline.
  • Aluminum radiator and water pumps are okay.
  • Cam lift: GM .390/.410, Ford .425/.450, Dodge .390/.420, Pontiac .388/.424.  Camshaft may be degreed.  No gear drives.
  • Carbureted or fuel injection allowed.  Factory stock fuel injection systems only.  No modifications or high performance parts allowed.  All electronic brain boxes or components must be stock and factory sealed.  This shall be strictly enforced and a factory stock fuel injection system that is suspected of being tampered with or altered is subject to be impounded and shipped to another location for additional tech.
  • Factory OEM stock 2 or 4 Barrel Quadrajet (choke plate may be removed). Holley 4412 500 cfm with Mr Gasket PT#1929 adapter. May remove choke plate and shaft, change jets, power valve and accelerator pump. No secondary metering block. Ford my use Mr Gasket 1933, which is a 2 barrel to 4 barrel adapter.
  • Ford may use Holley 1850.  May remove choke plate and shaft, change jets, power valve and accelerator pump.  No secondary metering block.
  • Lifter Valley baffle and screens are okay.
  • OEM four eyebrow flat top pistons are okay. Stock type replacement with stock type configuration, forged pistons ok.
  • Any air cleaner, steel top.
  • Aftermarket power steering pump and engine cooler are okay.
  • All internal components cannot exceed factory OEM specs.  It is your responsibility to provide factory data to back up your specs and not the tracks. Push rod length allowed: OEM Factory stock length or shorter for geometry. Heat Treated is allowed.
  • Stock configuration style solid motor mounts allowed and must be mounted in stock location. May chain, strap, or use OEM replacement urethane motor mounts. Examples of what is ok, but not limited to are Moroso Kit #62610 and #62630.
  • Cast iron intake only.  No marine intakes.
  • Z/28 flywheel is okay.  Minimum weight is 14 lbs. Flywheel, pressure plate, clutch must weigh minimum 35lbs. with bolts.
  • There is an option of any hydraulic cam with max valve lift of .450 allowed.       There is a maximum compression of 150lbs maximum strictly enforced and must pull 17 inches of vacuum with no tolerance.
  • Crankshaft OEM stock may use scat or eagle replacement, cast or forged, minimum weight 48lbs or forged (51lb), no tolerance. For example, 3.48 stroke for Chevrolet, no knife edge, may balance. No grinding on any part of crankshaft. Must have a legible part number, if there is no part number it will be deemed illegal.
  • Rocker arms 1.5 ratio stamped steel only. No other ratio, no roller tip, no roller.
  • Connecting rods stock OEM or eagle or scat replacement rods. (3-1 cr 5700P Cap screws ok. Example Chevrolet 5.7.
  • Balancing of the rotating assembly is allowed. No lightening or excessive grinding or shaving of rotating assembly.

Drive Train

  • Rear end must be strictly stock for make and model.  Welded rear end is okay.  Mini spool is okay.  C-clip eliminator kit is allowed.
  • May use aftermarket OEM replacement axles.
  • Transmission must have all working gears.  Factory type mounts.  Automatics must run 10” stock torque convertor, no shift kits, no dummy convertors, must be stock.
  • Engine location in stock position for make and model in factory mounts.
  • Solid hub clutch discs are okay.  Must be full circle.
  • No lightweight clutch assemblies. Clutch, disc, pressure plate and flywheel must be a minimum 35 pounds no tolerance. This will include flywheel bolts and cover bolts. Does not include release bearing assembly. No light weight clutch covers.
  • Cars that did not come with a standard transmission can use a hydraulic clutch pedal only.


  • 12 volt battery fired ignition only.
  • OEM points or HEI distributor only.
  • May use billet distributor housing.
  • Distributor may be locked.
  • No printed circuit board modules.
  • Alternator is okay.


  • Stock OEM cast iron manifold or under chassis header with 3 inch collector.       $210 max on header.       Must show receipt or part number for header.  Exhaust pipe must exit even with or behind the driver and no larger than 2 ½” all the way.
  • No center dump exhaust manifold. No step headers.
  • Mufflers are okay.
  • LS1 manifolds and truck manifolds are approved.


  • No additives allowed.
  • Pump or racing fuel is allowed. No E-85 or Propeline.
  • Maximum of 32 gallon fuel cell.
  • Cutting the trunk for the fuel cell is permitted.
  • No electric fuel pumps.
  • Fuel cell must be in 12 gauge can and centered.
  • Must be securely mounted with at least two 2” by 1/8” steel straps.


  • Stock factory OEM 4 wheel working brakes only (calibers must be the same size).No over or under size calipers
  • No brake bias devices of any kind.
  • May remove OEM proportioning valve.
  • No aftermarket brake pedals.
  • Brakes must retain OEM stock master cylinder and stock pedal assembly.
  • Rear disc brakes allowed but not mandatory.

Wheels and Tires

  • Maximum 8” wheels.
  • Minimum 7/16” studs with 1” lug nuts on all 4 wheels.
  • 3 steel wheels 15 by 7 or 15 by 8. Left side wheels must be the same size.  Offset 3” or 4”, but must be the same size. 2” offset wheels are approved for the right side only.
  • No wheel spacers.
  • Tires must be DOT approved.  Radial 70 series only.  All tires must be same size except right front.  No LT or purpose built snow tires or any tire with mountain or snowflake symbol.  No recaps.  No racing tires disguised with DOT stamp. ie, no Wild Country All Terrain Mud Tires.
  • Tires must not exceed 2” from fender wells, except right front.
  • Right front wheel only 8” or 10” wheel with no wide fives.
  • Right rear only bead lock.
  • Hoosier, 26.5 or 27.5 by 8 by 15 series tire on right front only.  Medium compound tire may be used. RC4 tire is acceptable for the right front.       If running a 255/70 the right front can be on a 29.5.
  • Anything not mentioned must remain stock.
  • Cooper Cobra and Mastercraft Avenger GT Tires are acceptable.
  • You can run Hoosier A, D., H or mediums 26.5 or 27.5 on the right front or RC4 28 or 29





It is stated in the rules above what you can do to your car.  Anything else will not be allowed!  In other words, if it is not stated in the rules then it is not approved.  Please consult tech-man for certification only.  If not in writing, no “he said – she said” is acceptable by management. All tech decisions are final and a disqualification means ALL money, prizes, and points are forfeited.

No grinding or defacing of any casting numbers.  Any motor parts with missing or altered casting numbers are illegal regardless of the reason.  To pull and inspect a carburetor is $100. To pull a head, the protest will be $150.  To pull a camshaft will be $200.  To pull a motor out to check the bottom end will be $500 (of which $100 will go to the tech inspector).  Should the car be found illegal, the money minus the $100 on a motor being pulled will go back to the protesting party.  Should the car be found legal then the money minus the $100 should it be a motor pull will go to the car being protested.

A proper protest will be completed as follows:

The protest has to be done by the driver on the front straightaway immediately after the feature and only by cars finishing in the top five and on the Lead Lap.  The driver must notify the flagman or the front straightaway track official, which will then alert the car being protested.  The car will then be impounded in tech and the protesting party will have 10 minutes to present the money as stated above for what is being protested.  This must be presented in the form of cash, money order, or cashier check.  No personal checks will be accepted.  The track officials, and only the track officials, shall determine when the 10 minutes will begin and the funds must be presented to the tech man.