Plug readings

[Fab60]

Hey guys. Been trying to chase this overheating issue. Plugs look ok but some people say they look lean. I figure it’s slightly brownish to white color . What do you all reckon?

[Fab60]

Here are some more for clarity

[iain1967s]

It does look a bit weak to me - assuming you took the plugs out straight after the engine had been on a hot run, they should be more of a golden brown on the insulator rather than bleached white.

What number plugs are you using, and what spec is the engine?

Hint: a gunson colourtune can be useful, if you don't have access to an exhaust analyser

[Fab60]

Thanks for the reply Iain. The plugs I’m running are BP6ES on a 1380cc. I had the car setup with a massive vacuum leak as in was aware that the vacuum on the carb hose had fallen off. With the setup I had a brownish plug reading with brownish porcelain area as well, go figure huh? Well I have since plugged up that leak and figured the carb would be running rich now so I adjusted the mixture 1 turn out (lean). Mini idles quite nice and runs pretty well , problem is engine temps are getting hot. Maybe it’s time to richen up about a half a flat.

[Hipwell]

With unleaded fuel it’s hard to tell, ice white is lean, which that isn’t. Take a plu from a low mileage modern car and it looks like that after running perfectly. maybe change to a BP7ES plug assuming compression ratio is higher. Tad richer won’t hurt.

[Fab60]

Thanks Hipwell, this is what I suspected as well. Just to be on the safe side, I will richen up a quarter of a flat and recheck the plugs again. I’m running 100 octane fuel whenever I can as the fuel here in the US is rubbish at a mere 91 octane rating at most if not all pump stations

[Jt850]

Higher than usual engine temps often to do with ignition timing. Maybe double check that too.