What are the advantages and disadvantages of running my LS on fully advanced timing?

 

you dun wanna do that. retarting the timing you get less cylinder "pressure". ideal for force induction. advancing the timing, your increasing cylinder "pressure". more pressure.. more power. by fully advancing, youll create TOO MUCH pressure and things start happen. pinging... blown gaskets (rarely).. motor goes KABOOM. seriously.

 

The car only runs good when the timing is advance. When timing is normal the low and mid range torque is really bad ther jus feels like there is no power. but on advance low mid and top end is perfect and car runs really good. Timing is perfect and compression tests reveal 200, 200, 185 185

 

would it be safe if i jus run it on high octane fuel?

 

cant go wrong with running higher octane. i run about 4-5 gal of 115 aviation fuel mixed with my chevron 92. i still wouldnt "fully" advance your timing though.