94 P30 pinging

[WallyCJ7]

I have a light ping after the engine has warmed up.

Some background: The motor home has 45k miles, I've owned this motor home for 19 years and use it 3 to 5 times a year and I've never had a problem with it.  it overheated once when the radiator cap was not put back on all the way.  I refilled it with water on the side of the road and it never had a problem again.  Last February camping in the desert it was freezing.  since I failed to ever check the antifreeze and the radiator froze and split.  I didn't notice and I ended up sticking 2 intake values. I had it towed home and then I pulled the heads and had a value job done, replaced the 2 values, resized the valve guides, and surfaced the head.  I changed all 3 temp sensor, oil pressure.  after driving I heard a light pinging so I adjusted the timing from 7° to 4° and it was still pinging.  Adjusted it to 0° since it has a performance chip with no documentation. No help and went back to 4°. Did some more research and got a new AC Delco knock sensor and still not help.  Drained the gas down to 20 gallons, added VP octane booster with 20 gallons of 91 octane.  Still no help. 

 

Is there a possible difference in the valves they installed during the valve job?  I cant find anything about the type of valves required.  

 

During this process I purchased a newer rig and I'm selling the old one right after I fix the pinging...

 

Thank you in advance,

Steve