Any boat size, type and configuration with any engine size, type and configuration will be permitted, provided the boat is propelled solely by a water-jet unit(s), carries two crew persons and complies with all safety requirements including an approved roll-cage.

The use of fuels other than petrol is permitted, provided the fuel type is notified to the Event Organise prior to competition. The only Methanol (alcohol) fuel permitted is No. 5 (oil added). The use of nitrous oxide is prohibited.

Boats using methanol fuel shall display a red letter "M" on each side of the hull in bold lettering on a contrasting background. Minimum letter size shall be 7" / 17.5 mm.

When entering for any event all Open Class Drivers must be able to show proof of prior Jet Sprint experience (6 meetings minimum as a driver). Jet Sprint experience may be gained in Group A without restriction.  The minimum age for Open Class competitors shall be 18 years for a driver and 16 years for a navigator. Proof of age may be required.

Chevrolet Engine Specifications

Capacity:
412 cubic inches (6.752 cc) maximum swept volume

Material:
Cast iron only

Configuration:
Maximum 8 cylinders, internal combustion only. 2 valves per cylinder, pushrod operated. The nominal section of each cylinder must be circular.

Oiling System:
Wet sump only

Camshaft:
One only in OEM production location. No restriction to valve lift.Devices that vary the valve timing whilst the engine is operating is prohibited.

Connecting Rod:
Must be of ferrous alloy material external inspection only. e.g. inspection by arthroscope

Cylinder Heads:
Cast iron only. Valve angle 23 degrees only to block face. OEM production position only.

Intake Port Bolt Location:
OEM production location. No high port or raised runner heads.

Exhaust Ports:
OEM production location only

Valves:
Maximum sizes - 2.100-inch intake, 1.625 inches exhaust. Valves may only be opened by mechanical action, and only closed by means of coil springs. The following after market manufacturers produce complying cylinder heads: GM Bowtie, World Products, Dart, Pro Action. Cylinder head part numbers must remain on the cylinder heads as supplied by the manufacturer.

Induction:
Naturally aspirated only via a single 4-barrel carburetor with a maximum of 4 venturies. Carburetor throttle body bores or the butterflies may not exceed 1-11/16 inch diameter.
No additives may be discharged into the outlet tract.
Any device which alters the configuration of the manifold / induction system (e.g. moveable inlet rams) or exhaust while the engine is operating is prohibited

Exhaust:
No restriction on type. Noise emissions must comply with individual track rules as set out in the supplementary rules at given track sites.

Fuel:
As per International Group A Specifications. Control fuel must be used as directed by the AFJSA.

Chevrolet Engine Specifications

Crankshaft:
May be standard G.M. (Factory supplied mass production) or Scat cast steel new part no. 9-10442.May be ground to maximum under size to 2.06 But stroke must remain original (3.480). May be lightened only for the purpose of balancing (no excessive metal removal).

Conrods:
Must be standard OEM rods and standard 350 length (5.700) or Scat 4130 I Beam part no. 3-ICR 5700pMay be polished and shot peened and balanced one rod must remain unground for balancing.New rods bolts may be fitted and rods resized must be press fit pins in rods no circlipsor possi locks etc

Pistons:
Can be cast Aluminium or forged pistons allowed. Must be flat top pistons with (4) valve reliefs as supplied. May be balanced but one piston must remain original weight. No light weight pins or pistons.

Block:
Must be OEM mass produced cast iron block. New Blocks are available. May be bored to a maximum size of 4.060. May be decked, but piston must not protrude above face of block when assembled at TDC.

Sump:
No dry sumps allowed. Larger capacity sumps permitted. Oil pump must be fitted in OEM position.

Camshaft Lifters:
Must be flat tappet hydraulic Cam and lifters. Maximum 510 lift at valve. (Lift will be checked with a solid lifter)
NO solid cams roller hydraulic cams or solid roller cams or roller followers. All lifters must have preload. (No clearance at rockers). Lifters must be standard OEM Chev diameter no mushroom lifters.

Cam timing Component:
May be double row roller type chain or inverted tooth chain and gears. No gear drives.No belt drives.

Pushrods:
Open but stock length.

Heads:
Must be OEM cast iron manufactured heads no alloy heads. Cast numbers allowed are 3998997, 3973493, 3998993, or 333882. Heads may be faced but must be 70 cc or larger chambers.New World product heads maybe used Part No. 043610.New heads must have 1.94 inlet and 1.5 exhaust valves only. No throating or porting at all. Heads must be flow tested and stamped. Larger inlet and exhaust valves may be fitted. Inlet 2.020"exhaust 1.600"maximum size.
No porting or hand grinding allowed, no polishing allowed of cylinder heads. Valves may be blended in from the seat area to maximum of .625" from the seat area down the valve throat area but must be done with a cutter and concentric to the valve guide and not by hand grinding or polishing. When using world product heads seats must only be cut 200" from original seat. Valve spring seats must retain original ID and OD but may be machined down to the correct valve spring height.

Rockers:
OEM rocker or 1.5 ratio roller rocker 3/8 stud only. Possi locks 3/8 only allowed. No stud girdles.

Valve Springs:
Valve springs must be standard GM OEMs block springs or LT1 springs. No double or triple springs allowed. Standard OEM retainers only. No 10 degree collets or retainers.

Inlet manifold:
Any cast iron or cast alloy manifold but must be single 2 or 4 barrel. No fabricated manifolds. Single 2 inch spacer allowed (one only) No forced induction system or fuel injections or nitrous systems.

Carby:
750 vacuum secondary list number 3310 or 750 DP square bore. Part number to be 4779.3310. May have secondary metering block fitted to aid tuning.
Must remain visually standard with air cleaner removed. No grinding or milling allowed anywhere to the carburetor.No swapping of base plates or metering blocks or throttle butterflies or bodies.
MUST BE AS SUPPLIED EXCEPT FOR JETTING. NO EXCEPTIONS

Ignition:
Any points or electronic ignition. MSD and rev limiters permitted.NO MAGNETOS OR CRANK TRIGGER SYSTEMS ALLOWED.

Extractors:
Open except for individual track rules.

Harmonic Balancers:
Must run performance steel. Encased balancer that has the outer ring secured by circlip to inner hub must have retaining bolt and washer fitted.

Drive Shaft:
Must have SAFETY LOOP fitted at rear universal of drive shaft.

Engine Retainers:
Must be fabricated front mounts and fitted with engine safety strap.