Quote:
Originally Posted by 66AC
The actual reason the motor was rebuilt was due to an abnormal amount of wear on the woodruff key slot on the crank. The key, over time somehow was worn allowing the toothed gear for the timing chain to wander. This key eventually broke causing a backfire and the timing to go off. A few valves kissed the piston surfaces. So the forensics were that a shroud which holds the key in place was really never good and allowed the key to wander out a bit. The key became battered somewhat. The wear on the engine was minimal especially the bores. The engine builder mildly honed the bores. All new parts were fitted in the rotating assembly and as described. Essentially now the motor is fresh and runs really well so far. With the miles I put on the engine per year (est. 3000 yearly) it was actually in very fine shape after 26 years of use. My clutch plate was also replaced with a Centerforce and also the flywheel was replaced at the same time.
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Incorrectly torqued balancer bolt, or a replacement bolt that is too long are causes of this. The torque of the balancer bolt is the drive, not the keyway. Keyways and dowels are for assembly.
A friend of mine went down this route, including telling me my timing light was faulty. Checking for true TDC in car revealed the balancer was out.
Removal showed the key chewing up the balancer. Aftermarket ARP bolt was wrong for the engine.
Gary