Timing chain slap

[daantjie]

Hi guys

1977 450 SEL 6.9.

Anybody have a definitive way of telling if a noise is a timing chain slap? I am getting an intermittent tapping/ticking from the LHS cam box. Noise cycles "on" about every 5 seconds, then fades away only to return again. I already replaced all 16 lifters and cleaned out the galleries. Noise is still there. Preload has been set on all lifters with the "go no go" gauge.

I measured the stretch of the chain @ 12 degrees ATDC on the damper. So I know the chain needs to be replaced and soon at that.

The 6.9 has a ratcheting tensioner and thus does not suffer from the "death rattle" at start up. Thus the chain should always be tight, but I can lift and wiggle the chain on the LHS sprocket quite easily.

Any tips appreciated!