Engine chatter at heavy throttle

[joedrum]

hmmmmmm

 

[cooltech]

Stopped pinging must have been bad fuel ran some atf in it and good fuel two long trips and it stopped

 

[OldWrench]

Improper valve timing can cause detonation, generally by creating a lean mixture from the intake valves opening too early and then obviously closing too soon. I would pull your plugs and look for indications of a lean mixture.
You didn’t have the problem prior to changing the belts so I would take another look at your belts even though it is a pain to do. Also double check your valve adjustment.
With the engine running check the exhaust pressure at the tail pipe and see if it feels the same on both sides.

 

[Anonymous]

when you hear the pinging check the tachometer then bring a lower gear up to the same RPM and hold it there - if you hear the ping its going to be a motor issue if you do not hear the pinging then its going to be something to do with the drive train.
(ya I know this may be too obvious and I'm sure you already did this)

 

[cooltech]

I checked the belt twice to see if they are dead on and all marks are correct
and checked the valves they are adjusted correct I have not pulled the plugs too
look at them put I will today