Pings, High Timing? Carb And Fuel Injection Same?

[blueapple]

I'm setting timing on my engine.. which was newly put into the car. But whatever I do, it pings on full throttle. This happened when I had very low timing ( did it on purpose just to see what's the problem) and it happens when I have higher timing, but less....

I used to have a EFI car...MR2... and it pings when the timing is high, never when the timing is too low.

I don't know why is it pinging. and also, this pinging is alot quieter than the MR2 pinged, is it just the different type of engines? THis is a 5AF engine, for a corolla.

Any information helps!

THanks!