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6255 ARC Billet Rod, HF Predator Long Rod 3.707

6255 ARC Billet Rod, HF Predator Long Rod 3.707

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Product Code: 6255

The new ARC Racing billet "Long" rod for the Harbor Freight PREDATOR 212cc. This rod measures 3.707" center to center for a 1.188" crank pin with .490" wrist pin and is designed to be used with aftermarket high-performance pistons. For stock stroke and high lift cam applications. The longer rod ratio generated with this combination will produce horsepower in the mid to high rpm range due to increased dwell and decreased side loading of piston. Bearings and custom designed high tensile strength bolts are included.

*** Piston will require machining in this application. Approximately .075" will need to be remove from the piston dome depending on the block. ***

All of our rods are CNC machined from aircraft grade 7075 T-651 aluminum. Our OHV rods are designed to utilize the higher compression ratios and high RPMs of racing OHV engines.

Key Features Include:

  • Oil groove in the crank bore that is fed through a channel in the integrated dipper arm.
  • Oil groove in the wrist pin bore that provides a reservoir of lubricant to the wrist pin.

*The standard bore on a Predator 212cc engine is 2.756". The Wiseco Piston #11132p94 is for a 2.756" bore, which means it will yield approximately .003" piston to wall clearance. This is right where you want to be, so provided your bore is good and needs nothing more than a fresh cross-hatch honing, it will be good. If your bore is larger, out-of-round, or the engine has already been run for a while with the stock piston, you will need to go with a larger piston. Call us if this is the case.

Rod bolt torque: 170 in/lbs lubricated

Installation Instructions:

To install your ARC rod you will need a 12 point 1/4" socket and a QUALITY inch pound torque wrench. You will need an outside micrometer, dial bore gauge or plasti gauge, and oil.

Measure the crank pin diameter with the outside mic, it should measure 1.188" +/-.0005". Measure in several spots to insure roundness. If out of round more than .0005" it probably should be replaced. The crank pin finish should be smooth to the touch.

When disassembling the rod notice on the side of the rod with the part number there are two dots next to the separation point of the beam and cap. These dots help to re-orientate the cap and beam when assembled. The side of the rod with the part number engraved will always face the side cover side.

Make sure the bearing and rod serrations are clean and install the bearings. Lubricate the rod bolt threads and hand tighten the bolts. Using the torque wrench tighten the bolts to 60" lbs. Alternate each side to increase the torque by 20" lbs at a time until you reach 150"lbs. Then loosen the bolts and repeat the torque process. this helps seat the rod bearing especially on a new rod. Measure the bore with your dial bore gauge opposite the parting lines. If using plasti gauge you will have to install the rod on the crank and use in accordance the plasti gauge instructions.

The rod bore should measure 1.191 +/.0005". With plasti gauge you are looking for about .003" clearance. From .0025-.0035" clearance is acceptable. Anything outside that dimension please call 800-521-3560 for recommendation.

Once clearance is set apply oil to rod, crank, and wrist pin and install this time torque to 170"lbs.

Improperly torquing rod bolts is one of the most common causes of rod failure.


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