I am curious what is the top ring position for the factory pistons? Let alone all the ring-package positions from the crown.
Piston top ring position
- Thread starter Fahlin Racing
- Start date
Using triangle that points to valley as the 12'o clock point.
1st Compression: Halfway between 12 and 3.
2nd Compression: 180* of 1st ring, halfway between 6 and 9. Make sure 2N faces up.
Gap on inner piece of oil control ring, halfway between 9 and 12.
Gap on outer piece of oil control ring, 180* of inner, halfway between 3 and 6.
I may be backwards on the oil rings but the compression rings are correct.
1st Compression: Halfway between 12 and 3.
2nd Compression: 180* of 1st ring, halfway between 6 and 9. Make sure 2N faces up.
Gap on inner piece of oil control ring, halfway between 9 and 12.
Gap on outer piece of oil control ring, 180* of inner, halfway between 3 and 6.
I may be backwards on the oil rings but the compression rings are correct.
Well thank you :thumb:, but I guess I may have been too vague. I was thinking distances from the crown creating crevice volumes and the plan would be to reduce these entailing a shorter piston and therefore lighter pistons equaling a lighter reciprocation weight. I guess I will have to measure a stock piston and get blanks somehow and machine the ring positions.
Guy or somebody would have more precise measurements or what the real ones are, these are what I measure off a pre production LB7 engine piston I have. From top of piston to top of each ring groove.
1st: 0.395"
Expansion:0.673"
2nd: 0.879"
Oil: 1.098"
1st: 0.395"
Expansion:0.673"
2nd: 0.879"
Oil: 1.098"
That is much a appreciated durallymax! Gives me a good idea to think more on.
Top ring is just .020 over 3/8 of an inch down, I thought it would been similar to the Cummins.
Top ring is just .020 over 3/8 of an inch down, I thought it would been similar to the Cummins.