i have read on more than one occasion that the k20a2 utilizes f20c outer valve springs and b18c5 inners. so if this is the case could you not upgrade your valve train using portflow or other stiffer inner valvesprings. i apologize if my information is completely incorrect, this a is just a thought i have been bouncing around in my head. i would appreciate any input.

 

nobody knows?

 

bump for some answers?

 

from http://www.acuraparts247.com, '03-04 RSX Type-S:

007 14761-PCX-003 SPRING, IN. VALVE 8 2003 Acura RSX 6.60 5.61
008 14762-PCX-003 SPRING, EX. VALVE 8 2003 Acura RSX 6.60 5.61

from http://www.hondapartssource.com, '03 S2000:

005 14761-PCX-003 SPRING, IN. VALVE 8 2003 S2000 6.48 4.86
006 14762-PCX-003 SPRING, EX. VALVE 8 2003 S2000 6.48 4.86

if you have on 02 type s, u should change the springs the s2k but 03 and up, we dont have to worry about since we already have s2k springs. this just saved me about $100.

most '02s -- dual valve springs on both intake (blue) & exhaust (red) sides.
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)

sometime in late '02 model year -- switched to single springs on intake side (yellow). exhaust side (red) was still dual.
14761-PCX-003 SPRING, IN. VALVE (yellow)
14752-PRB-A01 SPRING, EX. VALVE (inner) (red)
14762-PRB-A01 SPRING, EX. VALVE (outer) (red)

sometime in early '03 model year -- kept single springs on intake side (yellow), and also switched exhaust side to single springs (blue). (Based on the part numbers, we can conclude this is not the same blue spring as on the 02's intake side.)
14761-PCX-003 SPRING, IN. VALVE (yellow)
14762-PCX-003 SPRING, EX. VALVE (blue)
if you're wondering which combo you have, it can probably be looked up based on VIN or engine serial #. or better yet, spend 10 minutes removing the valve cover and see for yourself!

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.

 

I have used valvesprings designed for a B series head,but it required custom shims,as the height is different than the K.The retainers are interchangeable though.