I just set the base timing on my 91 Formula 5.7L. I set it at 6 deg btdc as the sticker under the hood recommends. I advanced it to 8 deg and even 10 deg without noticing too much difference. The shop manual says 6 deg btdc at 600 rpm. I didn't have a tachometer but the one on the dash said about 650 rpm at idle. Do I need to get a tach and connect it to the distributor like the manual says? What advantage would there be to setting it more advanced?

 

You can safely run from 8-10* of timing without detonation. Advantages are better throttle response and a bit more "up top".

 

I run 10* with no problems. I also run 94 octane at all times though so it may or may not detonate with lower octane fuels. Set your timing up to 8* and then take it for a spin. If it doesn't knock then keep setting it up a few degrees at a time until it does and then back out a few degrees.