Do I have special pistons?

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mhobday25
E30 Zone Newbie
E30 Zone Newbie
Posts: 23
Joined: Mon Aug 18, 2008 11:00 pm

Sat Mar 07, 2009 6:37 pm

A while back I bout my 325 and after 1k the head went. When replacing the head and rebuilding it back up, I noticed that my pistons had a + on them. I haven't played about with BMW engines before but wondered if this signified a different piston type? The guy I bought a replacement head off of had different pistons in his, just flat topped. Mine had two small mounds on them, one large and one small on opposite sides. Sadly I can't find the pics I took from back then, but wondered if anybody could shed any light on it?

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sideshowbob
E30 Zone Newbie
E30 Zone Newbie
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Sat Mar 07, 2009 6:49 pm

Not sure if they are 'special' but the + sign could signify standard byt oversize pistons that are usually fitted after a rebore, ie + 10 thou etc.
StuBeeDoo
Engaged to the E30 Zone
Engaged to the E30 Zone
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Location: Up My Own Arse

Sat Mar 07, 2009 6:50 pm

Flat(ish) top pistons are 320i/323i ones. Have you got the right 'head? 325i pistons won't work with the 320i/323i 'head.
This is why I no longer drive an E30......

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mhobday25
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Joined: Mon Aug 18, 2008 11:00 pm

Sat Mar 07, 2009 6:53 pm

it works fine, had 5k out of it, just was looking at chipping it soon, so wanted to make sure I had a standard engine. It runs really well, not had a problem since the rebuild. It has had an amazing 21 owners, so may have been upgraded at some point, im not sure
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