Open class rules only.
Open 1958 and thru production
3500#, 4000#, 4500#,5000#, 5500#, 6000#, 6500#, 7500#, 8500#
WHEELIE BARS ARE REQUIRED and must meet classic specifications (see Classic rules). All tractors must have a working safety kill switch. Drawbars must not exceed 20” in height and less than 18” from the center of axle to hooking point. No part of the drawbar may extend rearward beyond the point of hook. Drawbars must be stationary in all directions.
No radial tires. No steel wheels. Two wheel drive only. No duals. Any cut allowed on tires. Any gear, 5MPH speed limit. Shifting of TAs allowed. Tire size regional choice 18.4x38 maximum.
Tractors must be naturally aspirated. No turbos or blowers, except Oliver 99GM, etc…. Tractors manufactured to use diesel fuel only cannot be converted to gas or LP. Any agriculture carburetor allowed. Number of barrels, throats, and venture, etc…. must be that of the manufacture’s replacement manifold permitted. Enhanced electrical systems permitted.
RPMs allowed will be determined by the Nebraska test chart. Any tractor not listed will use manufacture’s data. (20% for open classes) All tractors to have positive throttle stops.
Tractors must have the stock engine, frames, transmission, rear end, and axle housings or manufacture’s replacement. Stock heads and their replacements are to remain unchanged in outside appearance. No 7 bolt main blocks on Olivers; no 12 port heads, and no 99 heads. AC-WC\WD\WD45 can use D-17 engine; IH-H350; M, 450. JD-A\B\G can use power blocks. No M-M (800) heads or blocks. Dual exhaust not allowed except after stock manifold. No Oliver 1600 heads.
Oliver 88, Farmall M, Massey 44, MM-U, JD-G, Case C/D, JD-A, 1940 and up and like tractors are not allowed in classes below 4500#. Massey 33, Oliver 77, JD-A 1939 and down and like tractors are not allowed in classes below 4000#.