As the subject says ,when i switch to petrol i can hear pinging in the motor , does not do it on gas does any one have any ideas where to start looking for the cause.
Kev

A few questions for you - How many km has it got on it? Has the engine ever been rebuilt? What spark plugs are you using? PULP or ULP? What weight of oil do you run?

If a lot of km, then maybe deposits on the pistons. If it's been rebuilt, the head may have had some material ground off, raising the compression.

On mine, it was after an engine rebuild that it started pinging on a hot day with AC on when going up hill. That was even on PULP. I found using Autolite 985 spark plugs stopped it. Never pings on LPG. I didn't find the Autolites lasted very long though and would be hesitant about using with LPG.

I mainly run on LPG so I use NGK XR6 plugs and try not to use petrol on hot days.

Pull the spark plugs, what do they look like? Fouled up with carbon? What's the engines mileage & blow by like?

Does it ping on e10, or 95 or greater premium unleaded? Or only the cat's piss regular 91 ron?

Cheers

ToranaGuy