Background:
95 Eclipse (no letters, base mode I suspect); non-turbo.
Serial number is Canadian (not a model that was sold in the U.S.); so I’m told by those trying to look up parts.

I'm in the process of rebuilding my first 420A engine and I've discovered a few issues with my engine kit. I had the bottom boiled, bored (0.020 over) and honed and I’m finding some discrepancies between what the 420A service manual says measurements should be and what I’m getting.

Top ring end gap measures .020 to .021in
Spec says: .009 to .020in
2nd Ring end gap measures .019 to .020in
Spec says: .019 to .031in

The measurements were taken near the top, ½-way down and near the bottom of the stroke, and no filling of the ring end was done before the measurements were taken. By the book I take the measurements to mean that the 2nd ring is right where it should measure, but the top ring is over the limit and I would expect it to measure near the bottom of the range.

Question #1: Should I have the ring set re-ordered and expect the top ring to measure near the bottom of the range or am I missing something?

The machine shop was having some difficulty ordering the right kit because they could not figure out if my engine was 1996cc or 1997cc.

Question #2: How can one tell whether theirs is the 1996cc or 1997cc engine, and will getting the displacement wrong make a difference in ring size, affecting the end gap measurements?


I had the machine shop press the rod pins off and back on to the new pistons; three pistons look right but one is backwards. The stock rods are notched on one side and all notches were originally on the intake side.

Question #3: All rods should be facing the same direction with respect to the “front” mark (dimple) on the piston tops, right?

Question #4: What happens if any of the rods are installed backwards?

The forum describes the 420A block as being “over-square”.

Question #5: What does “over-square” mean?