I am taking apart a newly rebuilt (never run) engine that i recently purchased to check it out and I found that the 4th piston was facing the wrong way when compared to the 3 others (ie the 060 for 60 thou that is stamped on the crowns went 060, 060, 060, 090 for cylinders 1, 2, 3 and 4 respectively when you looked at them in the block from the top).
The rods were all in the correct orientation on the crankshaft as below;

Pistons 1, 2 and 3 have what appear to be a half arrows stamped onto them and these were pointing to the front of the block (oil filter side).
The half arrow on piston 4 was facing the rear of the block
here's a pic of how the 3rd and 4th pistons were oriented when they were installed in the block (pistons 1 and 2 were oriented the same as piston 3);

I was under the impression that the arrows on ALL pistons must face the front so that ALL pistons are in the same orientation?
Can anyone please confirm this as i want to make sure everything is right before i start putting it back together?
Cheers
Dave

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Your imagination is only limited by the size of your wallet
"61 850 original and crusty (Mavis)
"64 Smooth Roof Van (Colin)
"67 Deluxe resto project (Monty)

Don't think it will really mater but if it's upsetting your ocd then change it. small bore should be easy to swap it around on the pin but if it an interference fit ie: 1275 then you may risk squishing the piston onto the pin rendering the piston u/s { rooted} I have opened a few { removed head } to find 2 one and 2 the other, common cock up by machine shop coz they don't realise the rods are offset. Should run fine the way it is.

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120bhp with 450kg just fun waiting to happen

We were prob. drunk when we set it up last and thought this will be a good idea

Doesn't matter on a 1275 because the gudgeon pins are central. But it is important on a 998 or 1098 because the pins are offset.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

cheers doc, I've never played with a sml bore

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120bhp with 450kg just fun waiting to happen

We were prob. drunk when we set it up last and thought this will be a good idea

Thanks Doc-it's a 1275 so I'll put it back in as i found it!!
I was worried that I'd have to have the pin pushed back out and the piston reversed or replaced if it were ruined.
Cheers
Dave

_________________
Your imagination is only limited by the size of your wallet
"61 850 original and crusty (Mavis)
"64 Smooth Roof Van (Colin)
"67 Deluxe resto project (Monty)