6,000 CLASSIC MODIFIED SMALL BLOCK RULES
1. Maximum weight is 6,000 lbs.
2. NO Engine RPM limit
3. Any speed, any gear and no shifting of T/A or like transmission allowed.
4. All tractors must be neatly painted.
5. Tractors are intended to look like a stock farm tractor that has an automotive V-8 neatly
installed.
6. No extended or widened hoods.
7. Raised carburetor enclosures are allowed.
ENGINE
360cid limit with 1% tolerance. NO big blocks, NO turbochargers or superchargers. One automotive
production Cast Iron Block and Cast Iron Heads ONLY. Blocks and heads are to remain unchanged
in outside appearance. No overhead cams, no tunnel port manifolds, no more than 2 inches of
carburetor spacers, no magnetos. Exhaust pipes or headers must be turned straight up or down, no
flap type covers on exhaust, any single automotive or agricultural carburetor is allowed. Electric
fans, water pumps and fuel pumps are allowed. Pump gas and racing fuel is allowed. NO alcohol is
allowed.
FUEL
1. Tractors are to be naturally aspirated with a single gasoline carburetor.
2. No nitrous oxide, water and alcohol injection are not allowed.
3. No nitro methane or nitro methane fuel additives allowed.
4. E-85 is allowed.
TIRES/WHEELS
1. 18.4 x 38 tire size is the maximum. Any cut and any rim width.
CHASSIS
1. Stock frames or like replacements are allowed. Example would be a tractor with cast iron
tub chassis may convert to side rail frames.
2. Agricultural Sheet Metal and Ag Transmission rear end and axle housing no newer then
1975. Any manufacture sheet metal is allowed as long as it is from the same manufacture.
3. No lengthened or widened hoods.
4. All tractors must have a wide front end.
5. Center line of the front axle may be no more than 12 inches in front of the OEM axle
location.
6. Batteries and fuel tanks may be remote located in front of grill.
7. No part of the tractor including the front weight bracket shall NOT exceed 11 feet in front of
the center line of the rear axle.
8. Weights may not extend beyond the rear most point of the rear tires.
HITCH
1. Point of the hook must not exceed 20 inches from the ground or be no less than 18 inches
from the center line of the rear axle.
2. Adjustable draw bars must be stationary in all directions.
3. Top of hitch adjuster must not be attached above the center line of the rear axle.
4. Hitch mush be 3 inches wide by 3-1/2” inches deep.
SAFETY
1. REQUIRED: All drivers are required to wear approved fire suit and wear a DOT certified
helmet.
2. Wheelie bars are required and must support the weight of the tractor.
3. Rear mounted kill switch is required. Switch must kill the circuit to the ignition as well as the
fuel pump(s).
4. Dead man style throttle is required.
5. All tractors must be equipped with roll over protection whether it be OEM or multiple bar
design.
6. Seat belts are required when hooked to the sled.
7. All tractors must be equipped with rear fenders.
8. All tractors will be equipped with either a SFI scatter blanket or 3/16 inch steel band over
the clutch and flywheel area.
9. SFI flywheel and clutch required.
10. All drive-line couplers must be shielded 360 degrees.
11. Engine side covers are required and cover the area from the base of the cylinder head to the
top of the frame rail or oil pan.
12. Wheelie bars must not be connected to the tractors hitch.
13. Harmonic balancers are required to shield 360 degrees.
14. All tractors must be equipped with fire extinguisher within reach of the driver.
All tractors must be equipped with front stabilizer bars or ski’s. Ski’s must be 4 inches off the ground
and must be attached to the frame by at least 2 points of contact.
CENTRAL OHIO TRACTOR PULLING ASSOCIATION (COTPA) HOT ROD SMALL BLOCKS
Weight: 6000 #
Tires: 18.4 x 38 maximum
Age of Driver: 16 years or older, under 18 years must have parental consent.
Age of Tractor: 1972 and older, no home-made tractors
Fuel: No pressurized fuels, no nitrous oxide, no nitrogen methanol, and no propylene oxide.
Racecar gasoline, alcohol, and oxygenated fuels may be used.
Draw Bar: Drawbars must not exceed 20 inches in height or less than 18 inches from center of axle
to hooking point. No part of the draw bar may extend rearward beyond point of hook. No part of
drawbar is to be attached to any point higher than the center of rear axle. Drawbars must be
stationary in all directions. No clevis, absolutely no turnbuckles. Drawbar hole must be 3” wide by
3-1/2” deep.
Engine Rule: Must be 410 cubic inches or smaller, 6 cubic inches may be added to engines that
require a fresh re-bore, no engine may be larger than 416 +0 cubic inches, must be an industry
standard small block, no big blocks. Must be a cast iron block, cast iron heads, maximum eight
cylinders, two valves, one spark plug per cylinder, Camshaft in block. The (Pump) is a Tech tool
only; engines under protest may be subject to a tear down by the COTPA Tech Inspector and/or
COTPA Officials as they deem necessary. The (Engine Rule) will be in effect through the pulling year
2025. Center of axle to rear of block (where bell housing bolts on) is to be a maximum of 72 inches.
Manifold, Carburetor: One four barrel naturally aspirated carburetor. Any 4150 carburetor is
allowed. No predators, no dominator, no aerosol carburetors. No fuel injection, no throttle base
injection. All intake manifolds can be low-rise type. No tunnel-ram, no sheet metal/aluminum
intakes, no casted sheet metal type, no welded manifolds allowed. Headers must exit in an upward
direction.
IGNITION: All ignitions must use MSD model 6AL ir 7AL-2 system with RPM limiting chip. Tech
inspections performed by using MSD model 89952 RPM module/chip tester.
Engine RPM:
1. Tractor engines will have an 8000 maximum RPM limit.
2. Tractors must use MSD model 6AL or 7AL-2 system with chip limiter.
3. Boxes must be easily accessible for official to tech.
4. Boxes may not be tampered/modified. Rivets must be original. If you drill a rivet out, you will
have to buy a new box. If factory sealant/sticker is broken, a new box is mandatory.
5. Only the wiring per MSDs wiring diagram is allowed, and must be plainly visible. No other
wire may be attached to any of the MSD factory wire other than as specified per MSDs
wiring diagram.
Hood, Grill, Transmission, Rear End, Axle: All sheet metal to include Hood, Grill, Fuel Tank, (if part
of sheet metal) Side metal, and screens must be for that make and model and must maintain
original dimensions in all directions (width, height, and depth) but could be moved forward a
maximum of 8 inches as a complete unit/assembly. Sheet metal must be 1972 or older. Some sheet
metal modifications are allowed contingent upon Hot Rod committee approval. Agricultural rear
ends must also be 1972 or older. Crossing sheet metal with different manufacturers is permissible.
Bell housing and transmission may be removed if they were designed to be unbolted from the rear
end at the factory. Front ends may be homemade, maximum allowable wheelbase of 100 inches
from center of rear axle to center of front axle or manufacturer stock length if greater than 100
inches.
Total length of Tractor: Tractors maximum allowable length is 11 inches from center of rear axle to
the furthest point forward, including weights.
Safety Equipment: Helmet and fire suit, wheelie bars, ski bars, kill switches, fire extinguishers,
fenders, SFI damper, SFI flywheels and pressure plates, SFI bell housings, engine side shields must
be incorporated. Drive shaft from bell housing to transmission must be shielded. Roll cages must
be capable of supporting tractor and driver. No steel fans. All tractors must have wide front axles
with a minimum of 32 inches between inside of tires. All electric fuel pumps must be wired to the
kill switch. Neutral safety start switch is required. NO factory cast iron tub frames allowed. COTPA
General Rules Apply.