Ring Ridge?

[Andre3127]

I have a 325e block I'm building an engine with, and it has a significant ring ridge in the #1 cylinder on the front side. The others have a ridge that's almost undetectable except for the line under the honing marks.

Has anybody built a motor with cylinder and piston wear that's beyond the .0047" clearance service limit spec? Should I just run the damn thing? or consider overboring to 85mm and building a 2.8?

[ForcedFirebird]

Definitely bore it! Otherwise you run the risk of banging up your new rings to bits. The old rings were slowly worn to that shape, the sharp edges on the new rings will be screaming in pain.

[TobyB]

I think I can count on the fingers of no hand the number of
BMW engines I've taken apart that had a measurable ridge*...

...*unless something bad had happened to that cylinder,
like running with a leaking head gasket.

Bore it. John's always right AND the ridge will kill the ring and/or piston in short order.

t

[ForcedFirebird]

John's always right

Wouldn't go that far lol.



My pops likes to say "I thought I was wrong once, but I was only mistaken." :p


Honestly, though, just try and share good info with the community - most of it is based on experience.

[redlightpete]

You could probably find an m20 block for free with no measurable ring ridge. I’d leave one at the end of the driveway for you, but that probably doesn’t help you much in NY.

[Andre3127]

Definitely bore it! Otherwise you run the risk of banging up your new rings to bits. The old rings were slowly worn to that shape, the sharp edges on the new rings will be screaming in pain.

I always appreciate hearing from you FF. It just so happens that I have another block already in my possession, but it was sort of sold to someone. I asked him if be needed the block since he really just wanted the rotating assembly, but he said I could keep it if I need. It has a very slight ridge but I think when I hone it it'll go away. Almost feels like it's only combustion residue.

If the ridge is nearly gone, should I still bore it out?

If I make a 2.7i stroker using a b25 piston in a b27 bottom end (crank and rods), will the rings hit that ridge? I can't find any detailed specs of both pistons when it comes to upper ring to wrist pin distance.



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[jeffnhiscars]

A ridge reamer is your friend

[digger]

the first thing to do is measure it properly to see of its round, straight, tapered or what IMO

[Andre3127]

the first thing to do is measure it properly to see of its round, straight, tapered or what IMO

That's the plan, but I'm now probably just going to use my other block and save this one to turn into a 2.8 and bore it to 85mm.

I need to borrow a micrometer from work in order to measure the bores. That size is the one I don't have!

Thankfully, I have the equipment to bore out cylinders myself. Bread and butter for a bridgeport mill.

[TobyB]

Wouldn't go that far lol.


My pops likes to say "I thought I was wrong once, but I was only mistaken." :p

Once or twice (or maybe more :) ), I initially disagreed with something you wrote.

In trying to type up the response, invariably, I discovered it was MY misunderstanding,
not yours....

Thus, I realized the errors of my ways. :nice:
t

[ForcedFirebird]

...as long as we admit when we are :p