I think valvetrain between K20A and K20A2 are the same...
But Honda made some serious changes both in K20A and K20A2 during times
For example
Early 02 models had doulbe valve springs
intake (blue) & exhaust (red)
Part numbers
Double Red - Double Blue
14751-PRB-A01 SPRING, IN. VALVE (inner) (blue)
14761-PRB-A01 SPRING, IN. VALVE (outer) (blue)
14752-PRB-A01 SPRING, EX. VALVE (inner) (red)
14762-PRB-A01 SPRING, EX. VALVE (outer) (red)
RETAINERS- KEEPERS
14765-PRB-A00 RETAINER, VALVE SPRING, FLAT
14775-PRB-A00 SEAT, VALVE SPRING
14781-PR7-A01 COTTER, VALVE
INTAKE & EXHAUST VALVES
14711-PRB-A00 VALVE, IN.
14721-PRB-A00 VALVE, EX.
In late 2002 became the first change.
Changed double intakes valve spring and installed single (yellow), exhausts remain the same double (red)
Single yellow - Red double
14761-PCX-003 SPRING, IN. VALVE (yellow)
14752-PRB-A01 SPRING, EX. VALVE (inner) (red)
14762-PRB-A01 SPRING, EX. VALVE (outer) (red)
RETAINERS - Keepers
14765-PRB-A01 RETAINER, VALVE SPRING
14775-PRB-A00 SEAT, VALVE SPRING
14781-PRB-A01 COTTER, VALVE
INTAKE - EXHAUST VALVES
14711-PRB-A00 VALVE, IN.
14721-PRB-A00 VALVE, EX.
PHOTO
http://img163.imageshack.us/img163/8359/valvespringsredyellow2.jpg
In early 2003, became the second change
They kept the single intake (yellow) and changed the exhaust springs with single (blue).
Yellow single - Blue single (maybe from S2000)
14761-PCX-003 SPRING, IN. VALVE (yellow)
14762-PCX-003 SPRING, EX. VALVE (blue)
RETAINERS - KEEPERS
14765-PRB-A01 RETAINER, VALVE SPRING
14775-PRB-A00 SEAT, VALVE SPRING
14781-PRB-A01 COTTER, VALVE
INTAKE & EXHAUST VALVES
14711-PRB-A01 VALVE, IN.
ÎΕW
14721-PRB-A00 VALVE, EX.
In 2004 begins the confusion. Based codes have changed at some point - once unknown springs.
The YELLOW - BLUE (from S2000 ), replaced them with BROWN - BLUE.
Additionally have changed INTAKES camshaft !
Valve springs codes
1. 14761-PCX-003 SPRING, IN. VALVE (YELLOW) (NHK SPRING)
or
2. 14761-PRB-A02 SPRING, IN. VALVE (LIGHT BLUE)(NIPPON HATSUJO)
1. 14762-PCX-003 SPRING, EX. VALVE (BLUE) (different from 05 models)
or
2. 14762-PRB-A02 SPRING, EX. VALVE (BROWN) (NIPPON HATSUJO)
EXHAUST & INTAKE VALVES
14711-PRB-A01 VALVE, IN.
14721-PRB-A00 VALVE, EX.
RETAINERS - KEEPERS
14765-PRB-A01 RETAINER, VALVE SPRING
14775-PCX-000 SEAT, VALVE SPRING
or
14775-PRB-A00 SEAT, VALVE SPRING
14781-PRB-A01 COTTER, VALVE
K20Z1 Acura RSX Type-S 05-06
VALVE SPRING CODES
Intake Blue single - Exhaust Brown single
14761-PRB-A02 SPRING, IN. VALVE (LIGHT BLUE)(NIPPON HATSUJO)
14762-PRB-A02 SPRING, EX. VALVE (BROWN) (NIPPON HATSUJO)
INTAKE & EXHAUST VALVES
14711-PRB-A01 VALVE, IN.
14721-PRB-A00 VALVE, EX.
RETAINERS - KEEPERS
14765-PRB-A01 RETAINER, VALVE SPRING
14775-PCX-000 SEAT, VALVE SPRING
14781-PRB-A02 COTTER, VALVE (NEW ONE)
The original dual valve springs were an S2K/ITR combination (as
discussed on Hondata's web page), and dual springs have been used
successfully in other high-revving Honda engines.
Hondata tested the living hell out of them early on, and found valve float to start to occur
around 9300 rpm. There was NOTHING WRONG with the dual springs and they are not
"weaker";
quite the opposite, they are probably a stiffer setup than the current
single springs, and better resist valve float at higher revs. However
this means that in an overrev situation, they may have a tendency to
keep the valve down in the chamber a little too long and cause
piston-to-valve contact and thus bend valves. The single valve springs
may float a little easier, but at the same time allow the valve to snap
back quicker and possibly avoid contact with the piston -- thus the
theory that they might help prevent valve damage during a mild misshift.
(However, I could point you to an Acura-documented case of an '03 with
single springs, misshifted and had bent valves with the freeze data at
less than 9200 rpm...) another theory at least one person had put forth
was that the stiffer dual spring setup could actually snap the top of
the valve stem at high rpms.
The change to single valve springs probably has multiple reasons. Evolution of design and
materials, fewer parts = simpler assembly and lower cost, and slightly less reciprocating
weight for better performance.
