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Hi all,
More on the rebuild of my BT7 engine. A number of years ago I purchased
+0.030" AE pistons in anticipation of this rebuild. The AE pistons have 5
rings: 3 compression and one oil control above the wrist pin and one oil
control lower on the skirt, below the gudgeon pin. The pistons that came
out, which were the originals, had the conventional 3 compression rings and
one oil control ring.
I am wondering about that second oil control ring below the gudgeon pin and
whether I should fit it or not. I am not building a performance engine,
just want the highest quality job possible. The original pistons functioned
fine and I never had oil consumption issues in the 110,000 miles I put on
them. This engine had a bit of piston slap, which was typical of them. I
wondered if the extra ring lower on the skirt was to address this. Perhaps
it was a complaint from Austin Westminster owners wanting quieter engines?
Was the 5th ring for another application? I also wonder whether wiping the
oil off the bores by the lower control ring is a good thing or whether it is
better to have some cylinder wall lubrication from oil splashing onto the
cylinder walls.
I have searched for a service sheet on these pistons (thanks Scott!!) but
found nothing. I also searched the List Archives, and there are a few older
postings that suggest fitting all 5 rings, but no reasons why.
I doubt we can really know what is going on in there as the dynamics are
complex, but I would be interested in any experience anyone has had with the
5-ring pistons. Theoretical discussion is always welcome!
Best, Mirek
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vlink=3Dpurple style=3D'word-wrap:break-word'><div =
class=3DWordSection1><p class=3DMsoNormal><span lang=3DEN-US>Hi =
all,<o:p></o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-US><o:p> </o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-US>More on the rebuild of my BT7 engine. A number of =
years ago I purchased +0.030” AE pistons in anticipation of this =
rebuild. </span><span lang=3DEN-US>The AE </span>pistons have 5 =
rings: 3 compression and one oil control above the wrist pin and one oil =
control lower on the skirt, below the gudgeon pin. The pistons =
that came out, which were the originals, had the conventional 3 =
compression rings and one oil control ring.<o:p></o:p></p><p =
class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>I am =
wondering about that second oil control ring below the gudgeon pin and =
whether I should fit it or not. I am not building a =
performance engine, just want the highest quality job possible. =
The original pistons functioned fine and I never had oil =
consumption issues in the 110,000 miles I put on them. This engine =
had a bit of piston slap, which was typical of them. I wondered if =
the extra ring lower on the skirt was to address this. Perhaps it =
was a complaint from Austin Westminster owners wanting quieter engines? =
Was the 5<sup>th</sup> ring for another application? I also =
wonder whether wiping the oil off the bores by the lower control ring is =
a good thing or whether it is better to have some cylinder wall =
lubrication from oil splashing onto the cylinder walls.<o:p></o:p></p><p =
class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>I have =
searched for a service sheet on these pistons (thanks Scott!!) but found =
nothing. I also searched the List Archives, and there are a few =
older postings that suggest fitting all 5 rings, but no reasons =
why.<o:p></o:p></p><p class=3DMsoNormal><o:p> </o:p></p><p =
class=3DMsoNormal>I doubt we can really know what is going on in there =
as the dynamics are complex, but I would be interested in any experience =
anyone has had with the 5-ring pistons. Theoretical discussion is =
always welcome!<o:p></o:p></p><p =
class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>Best, =
Mirek<o:p></o:p></p><p class=3DMsoNormal><o:p> </o:p></p><p =
class=3DMsoNormal><span =
lang=3DEN-US><o:p> </o:p></span></p></div></body></html>
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