4 replies to this topic

[cjhols]

Hi I know this is a bit stupid but I can't find any documentation for spacing the 2 oil rings on the piston. I know about the compression rings but how do the gaps on the 2 oil rings relate to each other and to the spacer's join. And how do all of these relate to the 4 holes (2 each side of the piston) that are joind by a space (well 2 spaces) under the oil ring. I have included the diagram but it is unclear.

The next problem I have is which way the piston goes in. At the top of the piston is says TOP on one side and some numbers on the opposite side so does the word TOP face the engine number side or the opposite side?

Sorry for being stupid but thanks for your help
Peter

Attached Files

•  Piston.PNG   90.88K   16 downloads

[Pigeonto]

With the multi section rings I always keep the gaps as far away from each other as possible.Then I keep all ring gaps away from the throw of the piston which is the front and back on a Mini- but I dont think many folk bother with being that fussy as long as no ring gaps are above or below another gap.
Then I measure the piston to determine if the gudgeon pin is offset but havent ever found that on a Mini.If it is offset it's done to decrease the thrust on the side of the bore on the power stroke and you dont want to get that wrong. Otherwise I line them up so they all look the same and the writing is the right way up when standing at the front of the car--for my own satisfaction

[Guess-Works.com]

exactly as above, plus, if the piston has a thrust side it will usually be indicated on the top of the piston, sometimes by an arrow, but most modern pistons available no longer have a specific thrust side.

And finally there's nothing worse than taking a head off and seeing the markings on the piston not all the same way up, it shows a lack of attention by the engine builder, and usually means other things have been done without an attention to detail.

[cjhols]

Thanks,
So the slot under the oil ring has no bearing on where the gaps / ends go?

And any comment on correct way the piston goes in cylinder?

thanks Peter

[Pigeonto]

That's actually all been covered above, but when referring to the gaps in the 3 piece oil control ring,we meant that the gap in the expander,and the gaps in the 2 rings all should be as far apart as poss at say 1 oclock,5 oclock and 9 oclock...is that 120 deg apart? lol, not sure!!
If the pistons dont have offset pin--which we pretty much concluded they wont,but will have an arrow if they have- then as above,put them so they're all the same,nice to have the writing the right way up looking from the front of the car......but.... dont forget that the rods go on 2 and 2 so you'll have to work out which way round the rods will be 1st.