Do straight 6 engines tend to rest after turning off, with no2 or maybe no 5 cylinder, with the induction valves open and with fuel sucked into the combustion chamber ?

[daverclasper]

Bit intrigued

Thanks

[JohnD]

I've been told that any ICE will come to rest in one of two positions, so that wear on the starter ring is concentrated there.    Can't confirm that, or if true where those positions are!   Wouldn't be hard to do, by noting the valves' positions after a number of stops.   

And once it stops, some intake valves will be open, fully or in part, and fuel/air will have been drawn in by the descending piston.   But once it stops and any pressure difference equalised, air movement stops.  Your Q sounds as if you suspect an excess of fuel into 2 and/or 5.   Is this because you see plug or other differences on this cylinders?     If so, I suspect a different cause!

John

[daverclasper]

Thanks John. Sometimes no 2 and occasional no5 plug look oily. I think this may be fuel on sooty plugs after switching engine off, after slow moving city driving, as also possibly plug smells of fuel a bit?. Also car will also fire very briefly on first turn of starter without choke, even in freezing conditions, so I assume some fuel in cylinder/cylinders?

Edited August 15, 2023 by daverclasper

[JohnD]

Check your injectors!

 

[daverclasper]

On carb engine?

[DanMi]

I would think that a 4 cylinder would come to rest in one of 2 positions as 1 of the pistons is on the compression stroke a 6 therefore may come to rest in 1 of 3

[Wagger]

Number 2 and 5 cylinders are central to each carburretor. They can run richer than the other cylnders. My Vitesse always soots up number two cylinder first and the adjacent ones are just correct. I do not lke running them lean.

I can see no reason why the engine should stop in anything but random positions. The starter ring on a 'Six' shows wear in three parts of the circumference. Usually less obvious than on a four pot which wears in two areas.

Edited August 15, 2023 by Wagger

[daverclasper]

I first noticed about 5 years ago, though it doesn't do it all the time (why I thought, maybe not oil?).

Yes, I have noticed no2 and no5 cylinders tend to run richer, currently no2 is running quite a bit richer than 1 and 3. Have nipped up any looser manifold bolts, though not made a difference. No other ideas, though I don't cane the car, so maybe nothing to be concerned about?

Mixture has always appeared to be at times inconsistent, going by the colour of plugs, though not way off (aside from its been more so, as in previous sentence), so don't worry too much?   

Edited August 15, 2023 by daverclasper

[JohnD]

2 hours ago, daverclasper said:

On carb engine?

There are sixes that use ... Gasp! ... carburettors?  

[daverclasper]

3 minutes ago, JohnD said:

Gasp!

Is that what the engine is doing on carbs? 🙂