Looking for intermediate size piston rings

[myles]

The 90 525i M20 that I've got has intermediate size pistons in it, 84.06 stamped on the top. The rings are worn and the end gap is 0.8mm with normal range 0.2-0.5 end gap. So I'm trying to find some intermediate (or 00) size rings to put in it. Does anyone know a good source for these things? Patrick can get me some genuine ones for forty something dollars per cyl, but I want to see if there are any cheaper options.

Thank You

[rob101]

http://www.pelicanparts.com/bmw/catalog/shopcart/BE34/POR_BE34_ENGman_pg3.htm
oversized ring kit for 20 USD. are you getting the cylinders rebored? or just honing them?

[rob101]

when did you get a 525ia, i don't remember you having one of those.

[myles]

when did you get a 525ia, i don't remember you having one of those.

I got it about 2 weeks ago. It was only $1500, with a blown head gasket and also no a/c. I've just got to get the new rings and assemble to whole thing. Then try to sell it. I will just be honing the bores, they're glazed but not tapered.

[myles]

Thanks for the link. Those rings are 0.25 oversize. A bit too big for what I'm after. The ones that I'm after are 0.08 over.

[myles]

Has anyone got any other ideas?

[632 Regal]

file the ends of the rings?


Has anyone got any other ideas?

[myles]

I thought about doing that. Would I run the risk of breaking the ring?

I'm not very familiar with the brittleness of chrome or carbon rings.

[rob101]

Has anyone got any other ideas?
um I know its stupid but it just occured to me that the rings have been worn and not the block. so you could probably just chuck in some normal rings. do you have the Bore dimension?

[myles]

um it just occurred to me that the rings have been worn and not the block. so you could probably just chuck in some normal rings. do you have the Bore dimension?

I'm starting to think that some new standard rings will probably do the job. They will have a 0.25mm bigger end gap that the correct ones which will mean that they should just be within normal spec.

I spoke to a couple of local engineering shops and they thought that the engine may have been just outside bore size specifications when it was manufactured and got the intermediate pistons then. They also suggested that standard rings would probably be ok.

I don't have an accurate way of measuring the bores. I expect that they will be about 84.1mm +- 0.05. I will have to get myself a set of digital verniers one of these days.

[rob101]

as much as i respect verniers the clearances you're talking about in engine building you should really be using something more like a bore gauge.

[myles]

Thanks mate. That's why I'm the novice at these things and you've obviously had some experience.

I've got a mate coming over on Friday night with his bore gauge. We will decide on the ring size once we've honed it and measured it.

Thanks for your help

[rob101]

Thanks mate. That's why I'm the novice at these things and you've obviously had some experience.

I've got a mate coming over on Friday night with his bore gauge. We will decide on the ring size once we've honed it and measured it.

Thanks for your help
lol not really that much experience in terms of engine building. but its kind of part of my job to know. any kind of dial gauge becomes a mechanical engineer's tool of choice for measurement. Glad to hear you can get a hold of one. anyway I hope it goes well. those m20 525iA's are a bargain these days.