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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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#3 ·
sorry for the messages lima..:eek:

thanks for the help though.:thumbsup:

my setup is currently being installed:noes: cant wait:run:
 
#6 ·
Lima did u think of this? this is very smart..would have NEVER known that the exhaust rockers will fit on the intake side!!

Probaly much cheaper route than for someone to go inside the motor and switch the pin..bc if you lose that pin you need a new rocker assembly bc HOnda doesnt sell just the pin which is retarded.
 
#7 ·
well you dont just go in there and switch the pins. you need the whole assembly cause its from an A2 not an A3.

:fuu: tell me about the pin deal. i was like :srsly:

thats a load of :bsflag:
 
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#11 ·
i doubt ill have pics.. :( but ill see if i get some free time to open her up and snap a couple..

:fuu: i need to get my hands on a tranny to keep up

you keep making me :jelly: with everything you do

:bowdown::bowdown:
 
#13 ·
i know shit happens.. been :shady: all over your show off taking notes. :laughing:
 
#15 ·
nah not that im shy just dont wanna say or ask something stupid and start a whole section of people:laughat:
 
#17 ·
Thank you soooooooooo much for this thread!!!!!!!!!!!!!!!

now i dont have 50,000 pming me about this............ i can send them this thread :thumbsup:

and good luck with the 6-speed swap, its a breeze, imma tell you now 3rd gear is gonna be so fun :vtec: you'll be flying :weeeeeeeeee:
 
#19 ·
I'd say 150-200 ish.. Maybe less depends if they really wanna get rid of it..
 
#26 ·
yeah.. i had to buy two cause the first guy jipped me on the pins for the rockers :firemad:

you could probably get it cheaper if you :pray:
 
#48 ·
My car will be on the dyno again shortly for another N/A tune to test out the 6 speed at the track. we'll be testing out the rev range higher to make sure the car is actually tapering off at 7600.
 
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