Reply to "Timing mark"

Don't make too many assumptions re ignition timing off a stock harmonic balancer, Bob. After 42 years of life, the stock balancer's outer ring (with the timing marks) is known to move a little- always in the retard position. That shifts the mark and you can really do a mistiming number on some engines. Those 351-4V balancers were not bonded- only pressed together and rubber does shrink with age. I have a half-dozen OEM balancers '71-74 around my shop and all have shifted- one by 200 degrees! Find True TDC off #1 piston with a small OD degree wheel before trying to set timing or you may regret it.