engine noise

[driller]

I get a "crackling-cooling radiator vibration" type noise from the direction of the engine (hard to explain that one!). Happens when accelerating hard and starts at about 4000 revs. I''ve never noticed it before. Are my wheels about to fall off? Cheers, Driller Ice Blue Griff500

[dan]

Its not pinking is it?? I think mine is slightly off tune (or not tuned for the fuel I use) and pinks under really hard acceleration. Its due for a service soon, so I plan to have it tuned for 95 ron as there is nowhere near me that does super

[tvr_nut]

My Griff 500 pinks a bit on 95RON unleaded, at about 4000rpm with a lot of throttle (i.e. when both the mech and vacuum advance are doing their bit ). I have reverted to SuperU as I have some track events forthcoming, but also intend to get the timing adjsuted for 95RON at the end of season service. I am told a 1 degree retardation is all that is needed? N.

[Driller]

Had the dealer check mine out-the ignition was too advanced and after a tweak it's running like a beaut. What I didn't know however was that pinking is actually really bad for the engine and can result in broken pistons or something like that. Driller Ice Blue Griff500

[bosshog]

Can anyone explain what pinking is, and what it sounds like (I know thats hard!). I though it was somehting to do with fuel types and the engine not having the correct O2 sensor or something?

[marshy]

Imagine the noise of about 10 or so newton's cradles all going off out-of-sync with each other... Er, or something like that

[IPAddis]

quote:Can anyone explain what pinking is, and what it sounds like (I know thats hard!). I though it was somehting to do with fuel types and the engine not having the correct O2 sensor or something?

Sounds like someone rapidly hitting the engine block with a small hammer. Reproducable by putting the car in 5th at 30mph and flooring it. You should get a couple of seconds pinking before you crash I could be wrong, but I believe it is caused when the fuel-air mixture is compressed and explodes slightly before the spark is fired. Higher quality fuel has a higher octane which allows it to be compressed more before exploding. Retarding the timing means to adjust the timing of the spark to ignite the fuel before it is compressed too much. Retarding the ignition too much reduces performance. Pinking can cause piston wear if it happens over a long period throughout a large portion of the rev range. Or something like that. Anyway, I've had my timing retarded by 2 degrees and there is no more pinking. Make sure you inform them at the next service or they'll put it back to "normal" again. Ian A Griff 500