just changed the head gasket and rechecked the timing,,its spot on perfect 10 btdc,,runs drives fine,,but when it starts to boost it starts pinging badly,,and happen instantaneously,,not gradual ,,any ideas??
sounds like its driving fine, but you are getting pre ignition under boost (WOT)
DO 1 short experiment....run down your tank of gas...and then go to highest premium you can source....preferably 93, if not add some octane enhancer (lucas octane enhancer or torco)....you want your octane rating to be in the 93 / 94 range.
Try a short run under boost and see how your performance is.
(engine knock in a regular engine because of pre ignition is troublesome...BUT in a performance engine pre ignition can result in burnt piston or scored valve because of heat generated - so if its pinging/knocking immediately shut down). High octane does nil for performance but it assists heat management in performance engines by preventing pre ignition (that's why race gas is 113 octane)
If that solves your problem you just need to be into better gas situation....if not off to a pro shop for a custom tune.
cheers 04 cobra (dyno'd 575 rwHP, streetable at plus 94 octane)
If you're sure timing is supposed to be 10 deg btdc, and you had a look at the combustion chambers to check for excess carbon when the heads were off and they were cleaned, go to higher octane, lower the boost or set the timing back until the pinging is relieved. By the way, when the head was off was it also planed down or resurfaced? That could raise compression a bit. Then cut back on the timing if higher octane doesn't arrest the pinging. If you don't want to do that, try and lower the boost. The higher compression will compensate.
well its pinging because of predetination,couple common things cause it,too high of compression,timings to advanced,or the spark plugs are too hott...get a spark plug set that is one heat range lower than stock and increase ur fuel octane one level.this should cure your problem however double check ur timing and dont let this happen too long ull ruin main bearings and rod bearings, you could also melt the tops of the pistons..