Rings....

Stock flathead ring gap calls for way more than I have seen mentioned on here. I bought a stock set at the lawn mower shop and they are like .020 or close to that. Guys on here say .0025, what is the advantages of having it so close? Thanks for your time
 
That's what Wiseco recommends, but for a stocker with cast rings, we run the top ring just as tight as we can. .0025" is good for a top ring.
I've set them at nearly 0 before, knowing that during break-in on the dyno, the stock rings will wear and end gap will open a couple thou on it's own.
2nd ring needs to have more end gap than the top ring to reduce ring flutter.
3rd ring is just along for the ride.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
32 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
As Mr. Carlson says above, first and foremost the cylinder must be prepared to a high quality state.
The piston ring has an important job to preform in only milliseconds. The ring ends gap is not only there to provide enough clearance to avoid butting. The ring ends gap contributes to the gas pressure entering the ring land and pressurizing the area behind the ring to help seal it to the cylinder wall. Ring spring tension alone can not hold back cylinder pressure during the power phase.
There are many factors affecting your end gap decision.
For few examples: a freshly bored and honed steel cylinder with 280 grit Sunnen stones and an out of the box new ring, can be set up very tight. Because on initial break-in this ring is designed to "seat in" (ware) as is the 280 grit cylinder. This is proper and correct but takes some time to "come in".
The same scenario exactly with a cool bore. Only the aluminum cylinder will "come in" sooner,,, glaze.
Now with a healthy used cylinder or freshly fine plateau honed cylinder and a fine finished ground face ring, the gap will have to be set up a few thousandths looser. Because there will not be as much "ware in" at initial start up. Steel or Cool bore these will "come in" very soon.
A note here,, IMHO a good healthy "Used" cylinder with a fine finished ground ring is the best we can ask for. IMHO if the cylinder is not to be bored don't touch it ! Don't break the glaze, grow the glaze. Just think, how many laps does it take to equal a season of mowing lawns ?

Best, WP
 
As Mr. Carlson says above, first and foremost the cylinder must be prepared to a high quality state.
The piston ring has an important job to preform in only milliseconds. The ring ends gap is not only there to provide enough clearance to avoid butting. The ring ends gap contributes to the gas pressure entering the ring land and pressurizing the area behind the ring to help seal it to the cylinder wall. Ring spring tension alone can not hold back cylinder pressure during the power phase.
There are many factors affecting your end gap decision.
For few examples: a freshly bored and honed steel cylinder with 280 grit Sunnen stones and an out of the box new ring, can be set up very tight. Because on initial break-in this ring is designed to "seat in" (ware) as is the 280 grit cylinder. This is proper and correct but takes some time to "come in".
The same scenario exactly with a cool bore. Only the aluminum cylinder will "come in" sooner,,, glaze.
Now with a healthy used cylinder or freshly fine plateau honed cylinder and a fine finished ground face ring, the gap will have to be set up a few thousandths looser. Because there will not be as much "ware in" at initial start up. Steel or Cool bore these will "come in" very soon.
A note here,, IMHO a good healthy "Used" cylinder with a fine finished ground ring is the best we can ask for. IMHO if the cylinder is not to be bored don't touch it ! Don't break the glaze, grow the glaze. Just think, how many laps does it take to equal a season of mowing lawns ?

Best, WP
Thank you sir those are some fine examples for sure.
 
That's what Wiseco recommends, but for a stocker with cast rings, we run the top ring just as tight as we can. .0025" is good for a top ring.
I've set them at nearly 0 before, knowing that during break-in on the dyno, the stock rings will wear and end gap will open a couple thou on it's own.
2nd ring needs to have more end gap than the top ring to reduce ring flutter.
3rd ring is just along for the ride.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
32 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
It the oil ring is just along for the ride and you didn't have to adhere to the rules would you remove it or is it necessary in other ways?
 
It the oil ring is just along for the ride and you didn't have to adhere to the rules would you remove it or is it necessary in other ways?
It serves the purpose of dragging oil up the cylinder. If it were up to me, I'd eliminate the second (scraper) ring.
A 3 pc rail ring like the Wiseco and some Briggs IC ring sets would be better for an oil ring in my opinion.
 
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