ea81 pistons

vicgrin · 11-09-2007, 02:23 PM

is there anyone out their who knows which way the pistons face in an engine if some dick?+&d forgot to mark them when he took them out.
the pistons have a diamond to on side with a B in the middle, on the top of the piston

Dewie · 11-09-2007, 09:27 PM

Hi
EA81 pistons are installed with the oil ring locating pins facing the centre of the block ( towards each other ) and back in the bores from which they came from.

vicgrin · 13-09-2007, 04:56 PM

What if you don't know which bore???

Dewie · 13-09-2007, 08:16 PM

To late then, check each piston in each bore and try to match each one for the best average fit. But no more than .0025 in. clearance max. Over this will need at least new pistons. Borrow or bye a deglazing hone (the one that looks like a bottle brush) and deglaze the bores, clean the ring groves carefully and fit new rings

vicgrin · 13-09-2007, 08:25 PM

The Engine Has Been Precision Honed & Balanced New Bearings & Rings .........but I Forgot To Mark The Pistons.
Will I Need To Rebore & New Pistons?????????

mceagle · 14-09-2007, 10:16 AM

Original EA81 pistons are symmetrical (no piston pin offset and no 'fly cuts' for valves) and it does not matter which way they go up. That is why they do not have front identifying marks. It does not matter whether the oil-ring locating pin faces the back or the front. If they measure within tolerance then install them either way but it would pay to keep them all the same because next time they might be slightly 'off-set' worn and will need to go back the same way.

If the pistons and conrods have not been disassembled, then originally the Subaru symbol on the conrod was facing the front.

vicgrin · 14-09-2007, 05:08 PM

Someone wise once said, you ask enough experts you get the right answer.

Thank you to the people that responded
Regards vicgrin