Could someone , please explain when you say that they are running 20 ATDC or 30 deg BTDC? I know that idle timing ona gsr is 16 deg. Now if I were to run a DRAG set-up at 10 psi on 89 oct., I would have to retard timing 10 deg. right? The guys with th timing on the LS post were saying that it was safe to run 16 deg at 7 psi.Does that mean they are not pulling timing out? Please expllain.

 

20 ATDC? I'm not familiar with engines that need THAT much ignition retard.

Well, in case you didn't know, ignition timing is the time at which spark occurs between the compression and combustion stroke, measured in terms of degrees of crank rotation. 0 degrees is exactly when the compression stroke is finished and the combustion stroke is about to begin, which is top dead center (TDC). If your timing is set at 16 before TDC, spark occurs when there are 16 degrees of rotation left in the crankshaft before you hit TDC. You want the ignition set sometime before TDC because the air/fuel mixture takes a while to combust. If you set the ignition timing too far advanced, the flame front will smack against the piston while it's still coming up and cause pinging or detonation.

"safe to run 16 deg at 7 psi" means that people have set the ignition timing on an LS to 16BTDC while running 7 psi of boost without pinging or detonation problems.