Retard which timing?
 

Hey guys, 13B 4 port here, turbo. I have two MSD 6a boxes and just picked up a BTM unit for one of them. I know I have to retard the timing under boost to prevent detonation. Money is short so I could only afford the one BTM, which timing is the more important to retard for now, Leading or Trailing, or do I even need to retard both??

I would say the leading, but check the 2nd gen forum, those guys would know for sure.

I tried in the secong gen, no one answered me

Leading. It will still run with the trailing disconnected. It will not run on trailing alone.

Can't retarding just the leading plugs cause detonation? I've read that the trailings should not fire first...

Too much advance causes detonation.

I replied on the 2nd gen forum.

yes it will, just not very well at all... at least on NA cars thats true