Pinking

[MaestroMatt]

I have noticed that my car is pinking a little under strain - going uphill is when it is noticeable, and it doesn't do it when accelerating on flat ground. I am not really sure how long this has been going on for. What are the possible causes? I think the fuel mix is too rich but can this cause pinking?

[E_T_V]

It is unlikely that a rich mixture will cause pinking, more likely a lean mixture will.

Which engine is your maestro? I can't remember sorry. This is what I do on lindz's A series:

Check, clean and regap plugs - if the plugs are white then chances are you have too lean a mixture
Check all vacuum pipes
Check that if you suck on the pipe attached to the dizzy you can't suck lots of air through and you might if you are careful be able to hear the diaphram click. (if you can suck lots of air though it the diphram on the dizzy is knackered)
Check the dizzy cap is tight and secure - same for the rotor too
Check the ignition timing - you'll need a strobe thingy for this.

Another thing worth bearing in mind for cars that are left stood for long periods (months at a time) is that the newer types of petrol go off quite quickly (so you lose some octane rating which could lead to pinking)

If you try this and still have no luck let us know and we'll see what else we can come up with.

[MGTurbo]

Usual checks, base mixture setting, dashpot oil topped up, all vacuum hoses tight and not leaking, base ignition timing (which will have to be altered if running 95 RON). If the problem persist's it may be a build up of carbon, i.e it may need a de-coke.

Gareth

[MaestroMatt]

Originally posted by MGTurbo
Usual checks, base mixture setting,

How do I check the mixture setting? My gut feeling is that it is rich but how can I tell? In this cold weather, I am getting a LOT of smoke and steam out of the back when she is cold and a bit more than most cars when she is warm. Could this be unburned fuel etc or could it be just the fact that I have a 20 year old car without a cat?

[MGTurbo]

Rich mixture would be black smoke. Base setting can be checked in a couple of ways. Co meter I.E Gunson's, or by ear (turn up the screw until the idle speed drop's then back off mixture half a turn) and then checking plug colour after a run. Rich mixture won't cause pinking, lean mixture will/can can cause pinking.

Gareth

[threelitre]

Hi!

In addition to Gareth's comments: Running on LRP can cause pinking (as I had on my car on the last UK visit), even if everything else is spot on. Basically the ignition needs to be reset then (like for 95 Octane fuel).

Alexander