There was anther recent thread that discussed timing on a 4 port carbed 13B. However my '85 SE is mainly stock except for the intake is ported and it has custom headers and exhaust. It has oversized injectors too which means it usually runs rich (I'm probably gonna do a megasquirt which should relieve that problem and allow me to ditch the AFM.)

At any rate, what timing advance is "safe" for these engines? The FSM says 5 degrees on the leading at idle, but can I gain a little power by advancing a little more? Since detenotation at the wrong time is so bad for these I don't just want to set it wherever I may be getting the absolute best power without a little advice.

Thanks for the help

 

I think with an n/a motor you can get away with advancing it pretty far. On my turbo motor, I run it advanced quite a bit. I pulled my dizzy, advanced timing 1 tooth, then set it where it would normally be retarted a few degrees. If I run it more advanced than this, it detonates, if I run it less advanced it pops and sputters and kills my throttle responce, this is with 10-17psi of boost, so I think you could get away with a lot of advance on an n/a motor.

Detonation from too advanced timing sounds a bit different than detonation from not enough fuel. Detonation from not enough fuel it will feel like you hit a brick wall, it'll stop revving and detonate hard and fast. If it detonates from too much timing it'll still rev and run good, but you'll hear a rattling type of sound coming from the engine.