piston ring question

[ground hugger]

Hi
Just bought some new b&p ,the rear scraper ring is in three pieces.
Inner ring ,outer ring and central spring.Do the inner and outer ring gaps have to be at the top of the piston on that ring.Then rotate the middle ring 180.

Or is the first rings on the scraper at the top and the second ring turned 180 :? Thanks...Dave

 

[ronmidg]

couldn't find any advice in haynes, my Bentley split manual says "the expander spring must be located as shown in the illustration" with a arrow pointing next to the little end, Autobooks for the split recomends the gap in the scraper is positioned at the top when installed with the two compression rings staggered 120 degrees each way from this. Unfortunately "top" is not in line with the pin.

What I was tought as a boy was pistons and bores wear in the plane that the rods move, so put the scraper ring gap at 90 degrees to this, at the pin, front/back didnt matter, (same advice as Bentley), then stagger the two compression rings so none of the gaps line up, (half of what autobooks says). Three piece oil rings we treated the same way, position the scraper gaps for least wear, at each end of the pin, then stagger the compression rings gaps so nothing lines up. On a boxer engine I would probably make sure none of the gaps were at the bottom installed.

 

[ground hugger]

couldn't find any advice in haynes, my Bentley split manual says "the expander spring must be located as shown in the illustration" with a arrow pointing next to the little end, Autobooks for the split recomends the gap in the scraper is positioned at the top when installed with the two compression rings staggered 120 degrees each way from this. Unfortunately "top" is not in line with the pin.

What I was tought as a boy was pistons and bores wear in the plane that the rods move, so put the scraper ring gap at 90 degrees to this, at the pin, front/back didnt matter, (same advice as Bentley), then stagger the two compression rings so none of the gaps line up, (half of what autobooks says). Three piece oil rings we treated the same way, position the scraper gaps for least wear, at each end of the pin, then stagger the compression rings gaps so nothing lines up. On a boxer engine I would probably make sure none of the gaps were at the bottom installed.

Cheers for that pal
So rear ring gap at pin,middle ring gap at top and front ring
gap at 180 to the rear ring.No gaps at bottom is this ok

 

[ronmidg]

you might have guessed I haven't done this on one of our engines, but have on plenty of others, its what I would do, maybe someone can confirm or not?

Just re-read, and not sure what you mean by front and rear rings. For a three part scraper assembly position the two scraper rings gaps to line up with each end of the pin, I dont think the spreader ring gap position is important. For the two compression rings gaps, position these so they dont line up with either of the scrapers or themselves. And dont put any of the gaps at the bottom when installed.