timhenze

Car runs better with timing at a higher BDC over the timing gauge. When I put it on 6 BDC in get a backfire condition. Any Ideas?

JimLentz

Your marks on the harmonic balancer could be off. The outer ring can slip over time.

timhenze

How can check?

toobroketoretire

Over time the outer ring on the OEM damper will slip to a retarded position so when you set the timing it'll be retarded as much as the damper is retarded. If you still have the OEM damper its best to replace it with a modern silicon-rubber dampened damper that will have valve setting marks every 90 degrees and is marked up to about 50 degrees.

To illustrate how dampers can fail I had my 454" standing on it's hind end while I was tapping on the OEM damper to get it started when the outer ring literally FELL onto the timing chain cover. As in CLUNK. Thanks to Summit Racing I had a new one delivered to me the next morning.