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How-To: A2 Cams/Rockers in an A3 Head.

147K views 499 replies 60 participants last post by  typeflex 
#1 ·
I have been getting a lot of messages regarding on how I went about doing my A2 cam/rocker swap. Here is a thread to help guide anyone that may be interested in doing such a project that nets impressive gains for our K20A3's.

First you should understand how the K20A3 i-Vtec system works vs the K20A2 system.

Here is a demonstration of the K20A3:

K20A3 i-Vtec

Here is the K20A2:

K20A2 i-Vtec


As you can see, the A3 i-Vtec only operates two rockers. When you switch over to a 3 rocker system our heads still can only function the use of two rockers as we don't have a lost motion spring. To make the 3 rockers work a simple switch of the internal pins will make it functional.

The following pictures I got from a member on K20a.org named Jeremyinlinepro.

Here is how the pins are normally setup:



This is how they should look after switching the middle pin (longer one) with the shorter pin (spring-less) on the side.



Here you can see the big rocker is locked with the small rocker, this will always remained lock regardless of your Vtec engagement.





Therefore before vtec engages you will have half of your valves running on the "big cam" while the other half runs on the "small cam" similar to how the original A3 cam/rocker setup is. Once vtec engages the solenoid will engage all three pins together making all remaining valves operate on the "big cam".




If you wanted to go to an upfront cheaper route and not have Vtec at all, the well known "Vtec Killer" setup is even easier. All you need is 4 exhaust rockers like this one for example:



You would put these on the intake side making you always ride on the big cam. I chose to go with the A2 rockers as sure they are more expensive up front, but your MPG won't be affected as much for daily driving.

A common question that always arises is do you need Kpro or some sort of ECU management, the answer is simply yes. To operate smoothly and to get a good amount of power out of the cam, a tune is always a must. It has been proven over and over that a fully bolt-on tuned K20A3 averages 170-180 whp while a cam'd K20A3 can easily hit 200+ in the RSX.


I plan to add more potentially to this thread. If anyone has any questions don't hesitate to post. If you have done such an install please share your knowledge as well!

:beerchug:
 
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#239 ·
Okay guys I'm a little stuck here...
I'm in the process of the cam and rocker swap
The cam caps came off just fine, but to get the rockers off, you need to take the whole cam holder off right? Well I cant seem to yank any of them up :/ I have one cam out and have the sensors disconnected . So why wont the 5th holder budge? Man up and pull harder?
 
#269 ·
I just got my headers it will probly give me another small gain. An rbc manifold is gonna give me good gains with a type s throttle body, i have type s injectors now too. And with an exhaust all included would probably get me about 200. My friend that dynoed it said more gas is trying to flow through but because of the restrictions of a stock exhaust system im missing hp
 
#271 ·
Because honestly he is chocking the shit outta his flow, because yes he has cams but if the engine can't breathe cams are still worthless, he opens her up some it should gain a good amount, cause that's were all my power came from is buying quality bolt ons, I'm only on z1 cams and those are race cams or anything lol
 
#280 ·
So i just aquired a1exhaust rockers and have some skunk2 stage 1 cams and have been considering doing the vtec killer setup until my z1 build is finished....now I have the z1 rocker assembly aswell so should I run the z1 exhaust rockers or run the a1 exhaust rockers.???? My car is a dd not overly too worried about gas milage really though.....limarsx could u give me some input please...would also like some of ur expertise when install comes too if possible!!! Will pay ur gas...food..and supply beer for payment:p
 
#287 ·
Anyone have issues with their idle? At cold starts or first 15 minutes of driving the rpm seems to drop really low and sometimes it even stalls. So to avoid stalling I rev the engine to keep it alive. Once the car reaches to a certain temperature, car no longer stalls but however the idle is never consistent to what I have it set to. Its currently set at 1000 rpm and at times it'll idle at 800 or 850 or even 1200. Could this be an issue with my throttle body sensors or iacv?
 
#288 ·
My idle is the same way, cold starts it will idle at 500 or sometimes die without my foot on the gas, i have all my idle shit deleted like IACV and the idle asist too so that doesnt help, but to fix the problem just make sure the cable is tight from the tb to pedal, like as soon as you touch the gas it changes, that will help with the steadyness, and also up the idle some in kpro, yea my car idles at 1500 or as low as 1000 once its warm but who cares, id rather it idle a little high than have to deal with the almost stall outs in the morning....... or if the high idle bothers you just make sure the cables tight and keep that foot on the gas a little in the morning, i did that for a while :mam:
 
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