Why did you do it? Is there a small gain somewhere?

I noticed it in some sigs, and thought there was some info on thread somewhere, but my searches show more generic stuff about timing setups.

If this is something that will even in the slightest improve a regular trucks performance, I'd like to know, and also how to set it on these trucks with the "spout".

Only timing I've ever done was on a 460/carbed, and a 352/carbed.

Thanks for any insight or explanations.

Blair