Revised November, 2008. Revisions/clarifications
italicized. Refer to Official 2009 IMCA Operations and
Inspection Manual or General Rules.
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 PUBLICATIONS 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.
The race director shall be empowered to permit reasonable and
appropriate deviation from any of the specifications herein or
impose any further restrictions that in his opinion do not alter
the minimum acceptable requirements. NO EXPRESSED OR IMPLIED
WARRANTY OF SAFETY SHALL RESULT FROM SUCH ALTERATION OF
SPECIFICATIONS. Any interpretation or deviation of these rules
is left to the discretion of the officials. Their decision is
Click here for decal placement diagram
1. SAFETY EQUIPMENT: Rules
apply at all times car is on track. Snell-rated SA2000, SA2005
or SFI 31.1/2005 helmet
required. Roll bar padding required in driver compartment (Fire
retardant recommended). SFI-approved full fire suit
required. Fire retardant neck brace, gloves and shoes required. Recommended:
Fire retardant head sock and underwear; head and neck
restraints; collapsible steering shaft. Driver-side window
net required, minimum 16 inch by 20 inch ribbon or mesh style,
and must be mounted so latch is at top front of window. Minimum
three inch wide SFI-approved five point safety belt assembly
required (Y-type shoulder harness not allowed), must be mounted
securely to roll cage,recommended to be no more than one
year old. Kill switch required within easy reach of driver
and must be clearly marked ‘OFF’ and ‘ON’.
2. FRAME: 1964
or newer OEM perimeter American rear-wheel drive passenger car
frame only. No sports car frames. Frame must be full and
complete, cannot be widened or narrowed, and must be able to
support roll cage on both sides, exceptions are: weight jack in
original center line of spring tower allowed; frame may be cut a
maximum 36 inches forward from center of rear end housing; horns
may be removed in front of steering box; front crossmember may
be notched and boxed for radiator and/or steering clearance;
maximum seven inch wide opening in side of spring tower for
spring removal. Maximum two inch wide by four inch tall frame
stiffener may be welded directly to outside of left side frame
rail. See link
here to download
OEM frame dimensions. Minimum wheelbase 108 inches, maximum
112 inches, both sides. Maximum overall width shall not exceed
78 inches from outside of tire to outside of tire. No part of
frame can be lower than four inches from ground except front
3. ROLL CAGE: Must
consist of continuous hoops, minimum 1.75 inch O.D. tubing, with
minimum wall thickness of 0.095 inch for main cage,
frame-mounted in at least six places, low
carbon or mild steel recommended. Must consist of a
configuration of front, rear and top hoops connected by tubing
on sides or side hoops. Driver’s head must not protrude outside
cage with helmet on. Roll cage must be securely supported and
braced with minimum one cross bar in top halo. Foot protection
bar required. Main cage no further forward than rear of engine.
All bars forward of cage must be lower than hood.
4. DOOR BARS: All
driver side door bars and uprights must be minimum 1.5 inch O.D.
with 0.083 inch wall thickness. Minimum three driver side door
bars, parallel to ground and perpendicular to driver, and welded
to front and rear of roll cage. Passenger side must have at
least one cross door bar, horizontal or angled, minimum 1.25
inch O.D. with 0.083 inch wall thickness, and one top door bar,
minimum 1.5 inch O.D. with 0.083 inch wall thickness. Steel door
plate, 18 gauge or 0.049 inch minimum thickness, must be
securely welded to outside of driver side door bars and cover
area from top door bar to bottom door bar and from rear hoop
down-post to five inches in front of seat. Must be visible for
5. BODY: (See
diagram) No composite body panels allowed except roof rock guard
and hood scoop. Body must be same width, front to rear, and
parallel to OEM frame. Minimum ground clearance is four inches. Nose
panel must be flat with no fins or scoops allowed. Cooling holes
allowed. Nose panel may be no wider, or lower than two inches
outside of front frame horns. Nose panel must remain within
confines of front bumper. Engine compartment must remain
open (no side panels). Hood must be enclosed at rear. No panel
in front of right door to engine compartment. No inner panels.
No car covers. Must have front windshield and rear window
support posts. Driver and passenger side windows must have at
least 12 inch opening (height and width), measured at center of
window, between lowest point at top of window, whether roof or
roll cage, and highest point at bottom of window, whether
interior or body. May use Lexan in sail panels. May use full
windshield. Roof must be fiberglass or
aluminum, full size and rounded down in all directions (see
dished roofs allowed. Driver roof hatch allowed. Maximum 1.5
inch rolled down rock guard allowed on roof front. No fins,
lips, wings or spoilers. Maximum four inch plastic skirting
allowed on bottom of doors and quarters. No reflective doors or
quarter panels. On
right side, outside of tires must be widest part of car. On left
side, body may be maximum one inch outside of rear tire for
6. DRIVER COMPARTMENT: Must
have minimum three windshield bars in front of driver. Lexan or
aluminum cowl panel in front of driver can be no wider than
cockpit and no farther back than steering wheel. Minimum 0.125
inch aluminum, or 0.060 inch steel, complete floor pan required.
Aluminum high-back seat only and must be bolted in, using
minimum 0.375-inch bolts, next to left side frame rail and ahead
of rear tires. Bottom of seat can be no lower than bottom of
frame rail. Driver must be sealed off from track, driveline,
engine, fuel cell, cannisters and pumps. Oil coolers must not
protrude above interior. Accumulators cannot be mounted between
driver and left-side door bars. No driver-adjustable devices
allowed while car is in competition except brake adjuster. No
mirrors of any kind.
7. FRONT SUSPENSION: All
components must be steel, unaltered OEM, in OEM location, and
replaceable by OEM parts, exceptions are: tube-type upper
A-frames with or without aluminum or steel cross shaft, and
mounts can be moved; stamped steel OEM replacement lower
A-frames; rubber, nylon or steel lower A-frame bushings, no
offset or bearing type; welded or bolted shock mount on lower
A-frame; OEM or OEM
replacement ball joints allowed. Lower A-frames must be
right and left, and of same design. Lower A-frame mounts and
bolt holes on frame must be within OEM specifications. Sway bar
must be unaltered OEM.
8. STEERING: No
rack and pinion. All components must be steel, unaltered OEM, in
OEM location, exceptions are: outer tie rod end and adjustment
sleeve may be replaced by a minimum 0.625 inch steel rod end and
steel tube; spindles can be ground for brake caliper clearance
only; unaltered, OEM replacement Pinto spindles with ‘IMCA’
raised cast; bolt on spindle savers allowed; steel steering
shafts and knuckles only; driver compartment steering may be
modified, must be kept on left side. Spindles must be right and
left, and of same design. Quick release required - steering
quickener and steering wheel may be aluminum. Idler arm, pitman
arm, and center link must match frame.
9. SHOCKS: One
steel, nonadjustable, unaltered shock per wheel. One additional
shock allowed in lift- or pull-bar area. No
external or internal bumpers or stops. No threaded body,
front coil-over, air, or remote reservoir shocks. No Schrader or
bladder type valve allowed. Front half may be shielded. One or
all shocks may be claimed per event for $50 each, counting as
one claim on card, following shock claim procedures (Refer to
IMCA Operations and Inspection Manual or General Rules).
10. SPRINGS: One
steel, non-progressive coil spring per wheel only. Steel or
composite leaf spring allowed. One additional spring allowed on
pull bar or lift bar, may be progressive. Any coil spring must
be at least 4.5 inches O.D. No torsion bars, air bags or inner
11. REAR SUSPENSION: No
independent rear suspension. All components must be steel. No
covers allowed. All trailing arms/link bars must be solid
tubing. Rear of frame may be altered to accept leaf or coil
springs. Steel coil-over eliminators, or steel or aluminum
coil-over kits allowed - must conform to shock and spring rules.
One mechanical traction bar (pull or lift, not both). No
brake bars. Rubber bumpers allowed only on panhard bar and
mechanical traction bar. No sway bar. Solid safety chains,
cables or tethers permitted frame to axle housing only (cannot
be mounted to bird cage), no springs, rubbers or adjusting
devices on/or attached to system. Minimum 19 inch long panhard
bar, measured straight line, center to center.
12. REAR END: Any
steel approved OEM passenger car or truck rear end (housing and
carrier) allowed. Safety hubs (floater) allowed. All components
must be steel, except lowering blocks, axle cap, drive flange.
Inspection hole required in housing. Full steel spool, steel
mini spool or welded rear ends only. Steel axles only. No quick
change devices, or cambered rear ends. One piece drive flange
only. No torque dividing differentials. No scalloped ring gears.
13. BUMPERS: (See
diagram) Steel bumpers must be on front and rear at all times
and welded, or mounted with minimum .375 inch bolts.
Rear bumper must be constructed of solid square, or minimum 1.25
inch O.D. tubing with 0.095 wall thickness, and – similar to
diagram - no wider than five inches outside of rear frame rails.
If wider than five inches outside rear frame rails, must be
capped and bent forward 90 degrees, or constructed in a loop
design. Must have at least one upright, minimum 1.25 inch with
0.065 wall thickness, from bumper to fuel cell guard.
Two-bar front bumper must be minimum 1.25 inch O.D. tubing with
minimum 0.065 wall thickness (maximum 0.095 inch) mounted
frame-end to frame-end, no wider than width of material outside
frame horns and with bottom loop parallel to ground. Top bar
must be directly above bottom bar, minimum 6.5 inches apart,
measured center to center.
14. TIRES/WHEELS: Must
use unaltered Hoosier Race tire, G60-15 with IMCA stamped on
sidewall. No chemical softening,
conditioning, or grooving of tires (Refer to IMCA Operations and
Inspection Manual or General Rules for automatic penalties). Tires
may be ground or siped within confines of tread (not past
factory straight line). No re-caps. All wheels must display
white ‘IMCA approved’ decal and wheel manufacturer decal.
Aluminum or steel spacers only. May use IMCA approved bead lock,
on right rear only. External, steel bead lock only and it cannot
make wheel any narrower than 8 inches and no wider than 8.75
inches. Must use only steel bolts. Foam
type or plastic outer mud cover allowed on right side wheels.
Inner mud cover allowed on left rear only. Rim-mounted bleeder
15. BRAKES: Must
be steel approved OEM, operative four wheel, drum or disc. Must
maintain minimum OEM dimensions for hubs/rotors and calipers,
cannot be lightened. Bolt pattern may be changed. Larger studs
allowed. Rear rotors may be aftermarket 0.81 inch thickness
(new). Vented rotors only, no scalloped or ceramic coated
rotors. No brake shut-off or pressure sensitive devices. One
front to rear proportioning device allowed. Brake lines must be
16. EXHAUST: Round
tube headers only. All primary header tubes must enter directly
into one collector at same point at end of header. Schoenfeld
mufflers, stamped IMCA609, must be used if track has noise
reduction rule of 98 d.b. or more. All exhaust must go through
mufflers, two per car, one per header. No merge collectors. No
17. FUEL SYSTEM: Mechanical
or belt driven fuel pump only and must be mounted at front of
engine. Racing fuel cell required, maximum 32 gallon capacity,
must be in minimum 20 gauge steel container. Cell must be
securely mounted behind rear axle, between rear tires, minimum
of four inches ahead of bumper, minimum of ten inches above
ground. Must mount with minimum two solid steel straps around
entire cell, two inches wide and 0.125 inch thick. All cell
mounts must be steel, securely welded to frame/cage. Protective
tubing must cover rear and extend past both sides of cell. No
part of cell shall be lower than protective tubing. Fuel cell
vents, including cap vent, must have check valves. If fuel cell
does not have aircraft style positive seal filler neck/cap
system - a flapper, spring or ball type filler rollover valve is
required. Pick-up must be on top or right side of cell. Limit of
one fuel filter. No cool cans. Air cleaner top/stud cannot
direct air into carburetor. No top flow air cleaner housings.
One naturally aspirated two- or four-barrel carburetor only. No
adjustable throttle bore carburetor spacers.
18. FUEL: Gasoline
or alcohol. Racing fuel allowed. NO performance-enhancing
additives. Upper cylinder lube allowed with alcohol only. (Refer
to IMCA Operations and Inspection Manual or General Rules for
19. WEIGHT: Minimum
weight limit of 2,450 pounds, no tolerance, after race with
driver in car. No weights and/or loose objects in driver
compartment, above interior deck or outside body. Weights must
be securely mounted to frame or roll cage and painted white with
car number on it. Must be attached with at least two 0.5 inch
bolts. No titanium, magnesium or carbon fiber products. Only
carbon fiber components allowed are rock guard and hood scoop.
No gun-drilled, tubular, hollow bolts or studs. Steel fasteners
20. BATTERY/STARTER: One
12 volt battery only, must be securely mounted between frame
rails, and positive terminal must be covered. Car must have
capability of starting without being pushed or pulled. Car must
leave initial staging area on demand, unaided, or go to rear of
that race. Reverse-mount starters with OEM case transmissions
only, see transmission rules for specifics.
21. GAUGES/ELECTRONICS: No
unapproved cameras, transmitting or listening devices, timing
retard controls, or digital gauges (including tach). No
electronic monitoring computer devices capable of storing or
transmitting information except analog tach. No adjustable
ignition control boxes. One 12 volt ignition box allowed, must
be out of driver’s reach. No additional ignition accessories
allowed. Only change allowed to ignition box is one high-end
rev-limiter setting. This setting can be changed through one
chip only, or an internal setting inside box. No magnetos. No
electronic traction control devices (Refer to IMCA Operations
and Inspection Manual or General Rules for automatic penalties).
22. TRANSMISSION/DRIVESHAFT: Must
have at least two forward gears and one reverse, plus a neutral
position. With engine running and car in still position, must be
able to engage car in gear and move forward, then backward. OEM
production type or IMCA approved aftermarket transmissions
allowed - two-speed, three-speed, four-speed and automatic. No
five speed (or more) transmissions, ‘in and out’ boxes, or quick
change devices allowed. Functioning shift levers must be in OEM
location on all OEM production type transmissions. All belt
drive pumps must be mounted on front of engine. Flexplates must
be full, steel, unaltered OEM, or OEM replacement.
Flywheel/flexplate must bolt to engine between clutch assembly
and crankshaft and all driveline components within bellhousing
must rotate while car is in any gear. Transmission must be one
of the following designs:
OEM Manual: Must
have a standard OEM case and working disc-type clutch or
approved cone or disc-type coupler inside an explosion-proof
steel bellhousing. One flywheel only, minimum 8.5 inch diameter.
Diameter of clutch disc must be a minimum of 5.5 inches. Clutch
assembly must be steel, except housing, which must be steel
and/or aluminum. Bellhousing can have only a hole for throwout
bearing lever or hose, must be 270 degrees around top of clutch
and flywheel area. Standard or reverse mount starter allowed,
must directly engage flywheel.
remain in OEM or OEM replacement case, with a functioning OEM
appearing pump. Aluminum OEM bellhousing may be replaced with
aftermarket explosion-proof aluminum bellhousing. Original OEM
bellhousing must have approved scattershield constructed of
minimum 0.125-inch by three-inch steel, 270 degrees around
Aftermarket Manual: Must
be IMCA approved, aluminum case, with internal clutch. Must bolt
to explosion-proof steel bellhousing, and use full, steel,
unaltered OEM or OEM replacement flexplate with starter mounted
in OEM location. No coatings or paint allowed on transmission
Drive Shaft: Minimum
two inch diameter steel drive shaft and must be painted white.
Steel slip-yokes only. 360-degree drive shaft loop required and
must be constructed of at least 0.25 inch by two inch steel, or
one inch tubing, mounted six inches back from front U-joint.
23. ENGINE COMPARTMENT: Rear
of engine (bellhousing flange) must be mounted at least 72
inches forward from centerline of rear axle. Engine offset must
be kept within two inches of centerline of front crossmember
with engine level. Minimum 11 inch engine height from ground to
center of crankshaft. Radiator must be mounted in front of
engine. Cooling system may be modified. Overflow tubes must be
directed to ground between frame rails.
24. ENGINE SPECIFICATIONS: Any
American make steel engine block allowed. Aftermarket
and OEM performance blocks allowed. Steel heads and oil pan
only. Flat tappet cam/lifters and stud-mounted rocker arms only.
No stud girdles. No mushroom lifters, lifter
diameter and configuration must match OEM passenger block.
OEM firing order cannot be changed. No crank triggers. All
engines must be able to be used in conventional passenger car
without alterations. Engine mounts cannot be removed or altered.
Castings and fittings must not be changed. No machine work on
outside of engine. All belt driven accessories must be on front
of engine. ‘Wet’ sump oiling system only. External oil pumps go
with engine if claimed.
25. ENGINE CLAIMING RULES: Refer
to IMCA Operations and Inspection Manual or General Rules for
claim eligibility requirements.
(A) $550 cash, or
exchange, claim on engine, flywheel and balancing plates ($25
goes to wrecker and $25 to official for each engine).
Claimed driver has option of accepting cash, or exchanging
engines with claiming driver.
(B) Claim does not include - 1. clutch, 2. pressure plate, 3.
bellhousing, 4. headers, 5. carburetor, 6. starter, 7. motor
mounts, 8. oil/temp. sending units, 9. carburetor spacer, 10.
fan and pulleys, 11. clutch ball, 12. clutch arm, 13. throw out
bearing, 14. dip stick, 15. water pump, 16. fuel pump, rod and
plate, 17. distributor, 18. plug wires, 19. water outlet and
restrictor, 20. breathers.
26. POINT STRUCTURE/PROCEDURES: Refer
to IMCA Operations and Inspection Manual or General Rules for
27. EIRI: (Except
in rare instances) Decisions of IMCA Officials are final and
binding without exception. In some cases, track safety rules may
take precedence over IMCA rules - any discrepancy between IMCA
and track rules should be brought to the attention of IMCA. Any
rule changes or clarifications during the course of the year
will be amended at www.imca.com as well as published in Inside
IMCA, the official newsletter of IMCA, and will be
considered as an official part of these rules