Need to change the timing set on my 66. There is a weight that is pinned to the crankshaft gear, and it is slotted for the keyway. Kind of looks like one of the crankshaft weights only real thin. Do I have to reinstall this? Is this a 289 thing? New crank gear doesn't have a hole for the roll pin. Any info? Tommy
I believe what you are discribing is a Major Part that helps Balance the Crank on the "K" Code Hipo Engines........ If so then YES, you must reinstall it so be careful removing it. David.
If the counterweight was not there when you took it apart ... chances are your motor was dynamically balanced without one (after the fact). Hi-Po rods weigh more than stock rods do.. The counterweight was an inexpensive/quicky solution to engine balance issues.. jimbo
I believe Cloyes still makes the HiPo 289 crank gear with the hole for the roll pin. IIRC the Cloyes part# is S351.
Hi to all! The part that you are describing is unique to a K engine.It is very necessary to the balance of the engine.Known as part # C3OZ-6A360-A.You risk a severe imbalance if you assemble without it.This removeable counterweight required a thinner crank gear,and narrower timing chain for proper clearance.I would never mix parts or re use an old sprocket.So if the cloyes info is correct..use it and do it properly.Or have the sprocket you have already bought drilled.If the chain is not correct it will rub the counterweight..this puts metal in your oil--NOT GOOD--.MEASURE FIRST!! And be careful,rotate the engine a minimum of 2 full crankshaft rotations to verify nothing is rubbing.This is one of the easiest ways to restore lost horsepower,if done properly.Let us know how you progress.
Now my 2 cents. I have had many Hipo engines built and balanced with out the counter weight . They ran fine at race RPM's. It can ONLY be eliminated if you have the rotating assembly dynamically balanced as Jimbo said. I wanted it eliminated in the engines I had built because I felt it was was one more thing that could go wrong in a race engine . I always leave it in a show car engine even though I have those engines balanced as well because that is what a stock Hipo is expected to have. The bottom line is you can eliminate it if you have a desire to but it is a essential part to a correct appearing 289 hipo.
Plus if you are going to have the engine balanced without the counterweight, you may as well install a double roller chain.
