Outer Limits 4x4 Board

Hi,

Car is an 87 Hilux d/c. 4y-c

Recently in the last month or so my car has developed a pinging noise when accelerating.
At idle and when backing off the accelerator at any speed the noise is non-existent.
It is the same noise that the car makes when in a gear too high for a hill, if that makes sense lol.
Since developing the noise I have changed petrol stations and changed to premium for multiple tank fulls.
I have also changed the oil and oil filter.
I checked the timing and my manual says that the timing should be 4degrees at idle. It was at roughly 14degrees. I have moved the timing back to 4degrees but the noise if anything seems more prominent. :(
(Could it have been moved to a higher degree for a reason ?)
There is also vacuum pressure in the little emissions hoses, I don't really understand the hoses and their purpose so that wasn't a thorough test.

Does anyone have any suggestions as to the cause of this noise?

I have tightened the air box and checked the engine mounts.
To make things more confusing to me with a passenger in the front the noise is quieter.

What am I missing guys? HALP ME!!

thanks.

i got a 4y-c in my lux aswell and it pings when i put crap fuel in it (as in e10,normal unleaded) i now run the vortex 98 otane in mine,runs better..but you have already tried that..

check your distributor.

the distributor i have is an electronic dizzy and it is flogged out and the mechanic says thats why it pings when you put your foot down cause the distributor isnt retarding/advancing and makes it ping/misfire at times.

so might be worth to just check your rotor button,dizzy cap and points and the bearing on the shaft...

cheers..smiley..

Yep have tried the fuel types, will check the dizzy cap it's relatively new so thinking that won't be it. But won't rule it out.
By bearing on the shaft, do you mean center bearing on transfer case?
Because I am leaning towards that being the problem, there is a lil bit of movement there and it would be consistent with the noise, as the noise only happens when driving not just revving engine.
Thoughts?