044 Ring failure with Espian piston kit

[parrisw]

You said you did a little work to the ports? Do you have a proper curve to the port roof? As well as a proper bevel? Both can cause excessive wear on the rings.

 

[Brushwacker]

You said you did a little work to the ports? Do you have a proper curve to the port roof? As well as a proper bevel? Both can cause excessive wear on the rings.

I didn't know, didn't pay attention to it, but I filed just a little off outward and smoothed the edges with emory cloth.

 

[parrisw]

I didn't know, didn't pay attention to it, but I filed just a little off outward and smoothed the edges with emory cloth.

Hmm, well its pretty important, can you post a few pics of the ports from the inside?

 

[Brushwacker]

Might be a few days before I get pics, but I'll aim to.

 

[fidiro]

OP stated 0.004 to 0.005 which I've used as a rule of thumb for end gap per inch of bore. I don't know what the bore of a 372 is off the top of my head but it is certainly more than 25mm which would make the end gap too tight.

If this is a good way to find proper end gap then what should I expect to see on a 40mm piston? Might as well ask about a 46mm and a 49mm end gap?

 

[maico490]

If this is a good way to find proper end gap then what should I expect to see on a 40mm piston? Might as well ask about a 46mm and a 49mm end gap?

40/25 x 0.004 = 0.0064"
40/25 X 0.005 = 0.008" so 6.5 to 8 thou. As I said it is a rule of thumb I picked up somewhere but I can't remember where. Others may work to different numbers but all the Caber rings I've fitted recently have been right in the middle of this range as delivered.
One thing that is certain with ring end gaps is that too little is not a good thing.

 

[fidiro]

40/25 x 0.004 = 0.0064"
40/25 X 0.005 = 0.008" so 6.5 to 8 thou. As I said it is a rule of thumb I picked up somewhere but I can't remember where. Others may work to different numbers but all the Caber rings I've fitted recently have been right in the middle of this range as delivered.
One thing that is certain with ring end gaps is that too little is not a good thing.

Thanks for the tip. Just tested end gap on new 46mm aftermarket rings and it's at .009 almost fits .010 all the way.