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Help with Moss piston ring assemblyl.

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John_Progess

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I purchased my BJ8 pistons from Moss, County brand, and they have 5 rings, three compression (narrow rings)and what appears to be 2 oil rings (much wider). One oil ring is one solid piece and the other is made from three separate pieces which is what I am used to seeing. One oil ring groove is directly below the compression ring grooves and one is down below the rist pin. My question is which oil ring goes in which groove? There were no instructions with the piston set. Thanks and have a good day!

John
 
I don't know the answer. If you don't get any help here, give Moss' technical guys a call. I believe they are available till noon on Saturdays. They have access to manufacturer's instructions and specifications that aren't normally shipped with their products.

Mark
 
Hi John,
My 5 ring pistons were Federal Mogal. From the top was the 3 regular rings, three piece oil ring and wide single piece ring at the bottom. Mark's suggestion is probably best though, get the info from the horse's mouth.


FWIW: I've heard some negative things about County brand stuff. You may want to do a search here before you commit to installing them.
 
GregW said:
Hi John,
My 5 ring pistons were Federal Mogal. From the top was the 3 regular rings, three piece oil ring and wide single piece ring at the bottom. Mark's suggestion is probably best though, get the info from the horse's mouth.


FWIW: I've heard some negative things about County brand stuff. You may want to do a search here before you commit to installing them.
Click to expand...
I concur with that ring placement.

However, be aware that the lowest (1 piece) oil control ring is considered a "high tension" design, as opposed to the "low tension" 3-piece oil control ring-set. What that means, is that the 1-piece oil control ring will add parasitic drag, and cost performance.

If it were me, and assuming the pistons were of high enough quality and fit with the correct clearances, I would source a set of Total Seal "gapless" (usually top or 2nd ring only) ring sets with both oil control rings of the low tension design.

On the other hand, some builders just leave the lowest, high tension ring off completely.
 
The engine has already been bored to accept these pistons with a good fit. The pistons have also been balanced with the rest of the rotating parts. I was not aware of a problem with County parts. What seems to be the problem? If I leave the bottom oil ring off will that cause any problem? Do I specify that these pistons are +.020" when I try to find gapless rings of do I need to give groove dimensions? Thanks for any help.

John
 
John_Progess said:
The engine has already been bored to accept these pistons with a good fit. The pistons have also been balanced with the rest of the rotating parts. I was not aware of a problem with County parts. What seems to be the problem? If I leave the bottom oil ring off will that cause any problem? Do I specify that these pistons are +.020" when I try to find gapless rings of do I need to give groove dimensions? Thanks for any help.

John
Click to expand...
If your machinist was satisfied with the fit, that's good.

I've never used their (County) parts, so I'll let someone that knows more about them answer your question about the quality.

When sourcing piston rings, yes, you must always specify the bore diameter & any oversize (+.020" in your case). I also measure and supply the following meausurements for each ring: groove height & groove depth, as these can vary between manufacturers (hopefully, NOT individual pistons). I also specify "file to fit" end-gap, but that's just me wanting the final say in the fit.
 
John -

I think the main problem with County parts are the bearings they sell are pure crap.

I can't comment on the pistons - one thing worth noting however is if you purchase ring kits from the usual suspects (like BCS) you will receive properly made rings made in the USA, not by County. Since the ring kits aren't all that expensive, it is something worth considering. I recently put them on my A90 and they are very well made. I'd rather have all engine parts made in the UK, OZ or USA if at all possible.

Not sure why everyone is now sourcing from county, they aren't all that great.
 
I chose to go the route of not installing the bottem rings.
I was told that they just create drag and tend to wear the cylinder walls out. I have only run the engine for about an hour so I can't really evaluate it yet. I'll let you know if I experience any ill effects. My stock pistons didn't have the bottem groves in the pistons . I do rememember flat head ford v8 engines having the bottem wiper rings. I would have liked to install forged pistons but they were not within my budget at the time I was building my engine. Anyone have a good source for forged pistons?
Bob
 
Bob -

Removal of the bottom ring is a common misconception.

Actually whether it's on or not won't make a huge difference, but generally speaking leaving it on will reduce oil consumption on the motor over time.

The Oil control ring also helps seat the bottom of the piston and keeps it from floating around, so any reduction in wear from not having the ring on will increase wear from having a floppy bottom on your piston.

My BJ8 has has all five rings on it, it has 90K miles since the rebuild and it doesn't burn any oil and compression is still perfectly even across all cylinders. I reckon I have at least another 100K to go.
 
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