silverback
Member
I think Eric is
Talking about lapping the ring od to the cylinder wall.
Talking about lapping the ring od to the cylinder wall.
EV 6 intake center line
- Thread starter jhawk
- Start date
Racingcarb.com
Member
Lapping of OD of ring is as important as making sure bottum of ring is lapped and seals to bottom of top ring land. Couple ways to achieve this... #1 is to use perfect tension and rough enough cylinder for it to lap itself for perfect seal. #2 is to use lapped OD ring with lass drag finish on cyl which will make a touch more hp but is much harder to achieve without a perfect cylinder. Find cylinder just a few thousandths over bore size used and get some diamond lapping compound(green) and lap OD of ring untill OD is perfect. Lap bottum of compression on glass with 400 grit wet or dry paper with wd40.
While in this area I concentrate on keeping top of cylinder perfect becsuse its one of the most important part of process in making HP. Lately while looking for a different compression ring I've run across a ring manufacture that makes the perfect size and tension for a different application to allow a good bit of machining to get perfect size compression ring for clones with a little effort.
This when used with a certain size piston from a certain manufacturer will make more horsepower than any other because of the area from the top ring land up. Pay close attention to the area behind your compression ring as you will seal and make more HP if this area is filled with material(thicker ring or less dept on top ring land). All of this helps with the theory of filling area before making most of intake stroke which goes back to an earlier thread why retarding camshafts help if cylinder doesn't seal well. My testing and theory shows much better numbers with lower int centerline and very tight cylinder, piston ring land, ect up top. I like to not use a big radius in top of cylinder to help in this area as well.
Hope this helps.
While in this area I concentrate on keeping top of cylinder perfect becsuse its one of the most important part of process in making HP. Lately while looking for a different compression ring I've run across a ring manufacture that makes the perfect size and tension for a different application to allow a good bit of machining to get perfect size compression ring for clones with a little effort.
This when used with a certain size piston from a certain manufacturer will make more horsepower than any other because of the area from the top ring land up. Pay close attention to the area behind your compression ring as you will seal and make more HP if this area is filled with material(thicker ring or less dept on top ring land). All of this helps with the theory of filling area before making most of intake stroke which goes back to an earlier thread why retarding camshafts help if cylinder doesn't seal well. My testing and theory shows much better numbers with lower int centerline and very tight cylinder, piston ring land, ect up top. I like to not use a big radius in top of cylinder to help in this area as well.
Hope this helps.
Last edited:
madd dawg racing
Member
Eric you are still a thinker my friend, glad to see you still on the leading edge.
Just my 2 cents, from flathead days.
We would grind the OD of the rings, set the face angle, fine finish, to match the ID of the cylinder after honing with torque plate installed.
Cylinder finish could be described as a fine crosshatch, to be short.
Lap the top and bottom of the rings to a finish of 2000 grit and polish the ring lands. Install top ring with .004 ring gap. After approximately 600 laps the gap would be .006 and leakage 1% or less.
IMHO lapping the OD of the ring affects the face angle which is another area to pay close attention to.
Also IMHO,,, there's no cylinder finish better than a good USED cylinder with a new top ring that's properly prepared.
Sorry for contaminating this modern thread with old FH info,,LOL
Best,WP
Just my 2 cents, from flathead days.
We would grind the OD of the rings, set the face angle, fine finish, to match the ID of the cylinder after honing with torque plate installed.
Cylinder finish could be described as a fine crosshatch, to be short.
Lap the top and bottom of the rings to a finish of 2000 grit and polish the ring lands. Install top ring with .004 ring gap. After approximately 600 laps the gap would be .006 and leakage 1% or less.
IMHO lapping the OD of the ring affects the face angle which is another area to pay close attention to.
Also IMHO,,, there's no cylinder finish better than a good USED cylinder with a new top ring that's properly prepared.
Sorry for contaminating this modern thread with old FH info,,LOL
Best,WP
Raging Bull Engines
Member
I remember when the raptor 3 piston came out. At first there were only the crappy Briggs rings available. I ground hundreds of old style Briggs top rings from Burris down to the RIII thickness. Mag chuck and surface grinder. Sold a ton of them. About 6 months later Burris hit the market with their own. Which just happen to be their old style ring ground to the new thickness, same thing I was doing. So anyway, I didn't sell any more. I guess that was in about 1999 or shall we say " a previous millennium" .
Raging Bull Engines
Member
I would also make tension adjustments on the top and second rings from Burris. I had multiple cast iron sleeves of slightly different bores to process the rings. Stack about a dozen rings in the appropriate sleeve, put in the oven and set temperature to about medium low and shut the door. After a predetermined time I would remove them from the oven and wait until they assumed room temperature. After this procedure they were lapped on top, bottom and od. The od process involved a rotating sleeve turning (about 30-100 rpm) that the od of the ring was lapped inside. The sleeve made of chilled iron, ID honed (fun process) and of various sizes rotated while the ring was stroked up and down the bore with diamond paste. Under magnification but barely visible with the naked eye, after lapping there was a very very fine cross hatch that could be seen on the bore contact face of the ring, it probably lasted about 3 seconds of run time, but it looked cool.