Hello everyone, I just signed up and this is my first post. Some brief history of my project, it is my stepsons truck. 1993 C1500 4.3 V6. After a botched cylinder head swap by others and resulting cracked heads due to intake gaskets installed backwards I've replaced the heads and am completing the assembly.
After numerous searches a lot of reading I could not find a definitive answer regarding the two timing marks on the harmonic balancer. So I dug out my piston stop tool and proceeded to investigate.
To my surprise neither mark is at TDC. Rather it lies approximately half way between the two. After setting TDC to the new mark I discovered several previously adjusted valves to need reset. I went through them all to make sure. It may be possible the balancer has slipped but in reading several online articles it seems my findings my indeed be correct.
I would appreciate your comments.
Regards

 

It is keyed to the crank shaft. Let me understand there are two marks/lines on the balancer? Is this harmonic balancer something you got off the scrap, or?

 

Thanks for the reply. I believe the balancer to be original to the truck. It wasn't removed during the repair. And yes there are two timing marks both appear to from the factory. There are many references to the two marks on line but little info on actual TDC.

 

An update. The balancer had indeed slipped. The outer ring had moved about 20 degrees from its original location. I dropped the oil pan, pulled the timing cover, replaced the timing chain and installed a new balancer timed to the second mark. This corresponds to the correct zero degree spec. and is confirmed by the timing chain marks. Now to sort out the fan shroud issue caused by the body lift kit.

 

We have 1988 C1500 Cheyenne 4.3 L 262.
With 2 timing marks on the HB.Set the timing to half way between the two marks. rotated the distributor to the #1 plug.tightened everything back down.checked all my connections.fired right up!! I would have never figured it out. Thank you for the post.It was a real life saver!!