i had just recently rebuilt a 94 360 magnum motor, its been bored out .030 and it has a comp cams camshaft with a gross vlave lift of .480, also 24lb injectors, then pcm has been programmed for these upgrades. The problem i have is the fuel scync is set but when I run 91 oct in it spark knock hard in the final gear (46rh transmission) but when i run 110 oct. it stops. the problem i have is, is their a way to avoid running 110 b/c the cost where i live is 6.69 a gal. I enjoy this truck but not that much. Is their a additive that can help me?

 

Make sure you routes the plug wires per the FSM that you can download for free here in the faq/diy section. You should prolly run some colder plugs as well. You could always retard the timing a few degrees as well. Im sure someone with a little more knowledge on the subject may have some other ideas as well. You should be able to run that motor on 91 octane or less i would think.

 

What intake is on the motor? and what other mods? The only way to pull timing is to send the pcm back to who ever did the reprogram.

 

its a stock intake it has icon racing pistons in it with stock heads, the pcm was programmed by B&G performance

 

Sounds like the tune has too much timing in it.

 

now keep in mind here that my pcm is obd1 not 2 so im limited

 

Octane helps that much, so would regarding it at the chain, no? Backing off 4* or so would be roundabout equivalent would it not?

 

My phone hates me... *retard, not regard...

 

Nope, one is cam timing the other is ign timing two different things.

 

I'm aware, sending your computer out to have it flashed is expensive, especially if you have to do it multiple times and is one of the many problems when building an OBD1 motor. For the price of a couple/few PCM flashes you could have a standalone computer that you tune yourself at your convenience.

Did those pistons bump your compression ratio as well?