comments interspersed below...Brian
At 07:15 PM 02/01/98 -0500, you wrote:
>I am putting new pistons into a just-rebored 1275 cc engine, and need
>URGENT help from y'all please.
>
>Question 1. The original pistons had 4 rings, and the Moss replacement has
>3 rings and a shorter piston skirt. Is this OK?
Yes. Modern rings seal better, and Cooper S always had three rings anyway,
so these are ok.
>
>Question 2. The pistons are AE Hepolite (Moss part #420-160), and they do
>not seem to have a front mark. Do these pistons have a front/back
>orientation, or not? (Moss could not advise today, the catalog does not
>seem to say, and the pistons themselves have the markings described in the
>footnote to this message, and they are also not indicative. However, books
>like the Haynes one say to expect a front-facing arrow - see Ch 1, 48, para
>2.)
The pistons are symmetrical so it doesn't really matter which direction you
put them in. Other engines have pistons that aren't symmetrical, so there
you need to look for the arrow, or "front", which will be there if it's needed.
>
>Question 3. In the midst of all this, I do not want to put the connecting
>rods in wrong. They are of the NON-offset type, so perhaps it does not
>matter? If it does matter, on which side of the engine do the rod numbers
>go - camshaft side or NON-camshaft side?
All 1275 CC engines have offset con-rods - really! The numbers are stamped
at the first rebuild, not from the factory, so you need to look as you take
them out. 1275 rods can go in either way, as long as you get the off-sets
right. Just make sure that you get the rod caps on the right rods, and in
the right orientation. If you're not sure, get the rod big-ends re-sized
(always a good idea anyway).
Double check the ring gap on all the rings, and set them so that the gap's
don't line up.
Brian
>
>___________
>Footnotes. The pistons have no markings on the side or underneath. On the
>top near the edge, they have radial lines, each 120 deg from each other,
>none of which are aimed front or back - one points sideways, i.e., to the
>left or right of the engine. The one that points sideways has a second
>line parallel to it about 0.1 in away. On the side of the piston opposite
>to the sideways line, appears the casting and size inscription AE21251 +
>.030 AUF. The instructions do not indicate any orientation marks, but they
>look like they are for a different piston anyway (thanks Moss). The OLD
>4-ring piston also does not have a front mark that I can see.
>
>Would much appreciate some quick guidance on this one.
>
>Thanks,
>
>Daryl
>
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