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ENG: Vtec Head Swap HOW TO

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    ENG: Vtec Head Swap HOW TO

    This is directly quoted from Andrew on I figured many people would find this interesting and a big help. I think I may just have to do this mod But thanks to Andrew....

    Well, already in a week I've put on 1200 miles! (I drive a lot!). No oil leaks, no funkyness what-so-ever... I got my VTEC problem figured out, I cleaned out the solenoid and it started working fine.

    So here is the work-in-progress... some of you have seen it on HT, but that site annoys me too much and so lets work on it here:

    PS: I'll be adding various illustrations soon, so keep posted!

    In the quest for more power for my Accord I came to the conclusion that a turbo was the only thing that was going to make me happy. I toyed with the idea of the Eclipse manifold rig job or having something made. After seeing impressive dyno results of the SOHC VTEC engines with boost I decided that I must have this feature. I didn't really want to pull out my bottom end though. Knowing that the F series is MOSTLY identical to eachother (save the F23's which have different sleeves etc) I figured I could just plop a F22B1 head on the car. Another
    factor in this decision is the abundance of off the shelf turbo kits for the 94+ Accords. Having a manifold fabricated is a cool idea, but I just rather have an off the shelf kit. Whats really great about doing this is the price. Most swap-shops are trying to GIVE away F series engines...

    What you begin with:

    Well what better way to start off this how-to but with a parts list. My parts list assumes you have a 4th gen Accord. If you're a 5th gen owner you wont need the intake manifold, so just use your head on the rest. I'll also list the places and prices I paid:

    1.) F22B1 head; (eBay - $100.00) You'll need a valve cover too... which I got off a forum member for $30.00.
    2.) F22B1 or B2 Intake manifold & throttle body THIS INCLUDES THE THERMOSTAT HOUSING!!!; (Forum Member - $50.00)
    3.) 94+ water intake hardpipe (water pump to the thermostat housing); (Forum Member - $5.00)
    4.) Timing belt (the 94+ EX are specific due to the head being slightly taller!); (AutoZone - $45.00)
    4.) P0A ECU; (Forum Member - $35.00)
    6.) All associated seals & gaskets (Depends, but figure $100-120 if you're being smart and replacing old seals);
    7.) Exhaust manifold that'll fit a 94+; (Forum Member - Free)
    8.) 94+ Throttle Cable; (AutoZone - $22.00)
    9.) Proper spark plug wires. (AutoZone - $45.00)

    Tools what will make this job a lot easier or you flat out need:

    1.) Brass scraper (dont ass up your aluminum block & head scraping on it... be smart and use a brass scraper).
    2.) Crank pulley tool (I don't know how I ever survived without this)
    3.) Of course you'll need varying levels of torque wrenches, don't even attempt this without proper torque wrenches.


    MAP = Manifold Absolute Pressure sensor;
    IM = Intake Manifold
    TB = Throttle body
    VTS = VTEC spool solenoid
    VTP = VTEC pressure sensor
    IAC = Intake Air Control (called EACV on older hondas... what I'm used to)
    EM = Exhaust manifold
    IAB = Intake Air Bypass solenoid

    Taking it apart:

    I'm not going to dwell on this too much. If you're going to attempt this you damn well better have a service manual! Basically keep taking things off until you have a bare head in front of you. My engine was leaking oil pretty bad from the oil pan and front main seal. Since you'll be up there to replace the timing belt anyway why not change all those too? I also took this time to really degrease and clean my engine, transmission and compartment.
    So, in review heres everything I replaced/freshened up:

    1.) I removed the oil pump housing and made sure the oil pump rotors were within service limits.
    2.) Replaced all orings, front main seal, and balance shaft seals.
    3.) througly cleaned and scraped the oilpan and oilpan mating surfaces & replaced the gasket.

    Assuming you're a 4th gen owner, go ahead and pull out the water intake hardpipe on the back of the block use it to launch a bottlerocket or something. Install the 94+ pipe and call it good.

    Prepping the head/block & others:

    In todays world of multiple-layer metal head gaskets, head/block trueness & cleanliness are of utmost importance ...if you want a head gasket that wont pop on you in 20 miles. Throughly scrape the head and block with a brass scraper. Caution must still be taken even with a brass scraper to not nick or gouge the delicate aluminum surfaces. Hopefully you took the time to clean the engine compartment, block & head before reassembly as well! Also take care that pieces of old gasket & muck dont fall into the oil gallery drains or water jackets by using rags.

    On the bench go ahead and bolt the intake manifold to the head if it isnt already. Its just way easier on the bench.

    Finally for us 4th gen owners... there is a bit of business we need to do on our heads. In 1994 Honda redesigned the F series a bit on the front middle head bolt region. They added a little ledge that covers/seals a water casting hole from when the head is molded. They use those to sand cast the aluminum. Why is that a problem you ask, well as I found out (the hardway I might add) without that ledge it LEAKS water (pours is more accurate). Therefore it MUST BE SEALED. I used a crapload of JBweld (I love this stuff!). Feel free to seal it however you please, but do it or enjoy no cooling system. Once again this only applys to 4th gen owners. I assure you this hole is only a sand casting drain and on the 5th gens is totally sealed by the headgasket against the ledge.

    Prepping the wiring harness:

    For the most part this will remain unchanged, but a couple things do need to be added and one item moved. You'll be adding 3 wires:

    1.) VTEC solenoid trigger
    2.) VTEC pressure sender
    3.) ground wire for VTEC pressure sender

    Add these 3 wires to the thermostat housing/EGR area of the wiring harness and we'll discuss ECU pinouts later in the how-to.

    Now the item that needs to be moved is the IAC / EACV (whatever you wanna call it) plug & wires [2]. You'll find this plug on the plastic injector wiring bar. Open the plastic injector wiring bar and pull out as much of it as you can from there. Cut the connector off and untape the harness enough to get the 2 wires heading toward the TPS sensor connector. You're going to have to solder about 12-14" of wire to make it reach. I just loomed the TPS & IAC together and made a Y so they could reach their respective recepticals. As I said earlier this is the OPTIMAL time
    to totally retape & loom the wiring harness if yours looks bad like mine did.

    Finally you're going to have to make a choice on the MAP sensor. You can either A.) find a connector in the junkyard that will fit the MAP on the TB or B.) reuse your MAP sensor and just run a long piece of vacuum hose over to the drivers side of the IM. I chose option B for right now. If you're a 5th gen owner this doesnt apply to you.

    Prepping the ECU:

    This was really easy for me. While I do have brand new pushpins (hey I used to do a lot of motorswaps) I reused what WAS my automatic rear motormount solenoid (this is also the IAB on 90-93 EX models or anything else that was equiped with IAB) and powersteering (I removed mine) pressure sender pins. If you didn't already know Honda was really nice and you can snap open the connectors on the ECU side and move pins around. No matter WHAT way you decide to do this you need to add two pins: D6 (VTP) and A4 (VTS) [See wiring harness pinout chart I've included]. The VTP ground... well just ground it anywhere. It doesnt matter, its just a simple on/off pressure switch.

    NOW for 4th gen owners we get to do a little more work/make a choice. In 1994 Honda decided to swap pins A11 and A6 (EGR & 02 Heater respectivly). To my knowledge this is the only OBDI car Honda did this on. ANYWAY your choices are as following:

    1.) Swap pins A11 & A6 while you have connector "A" apart adding VTP. You're going to have to actually cut and solder them though. Unfortunatly A6 is a big pin and A11 is a small pin (two different pin sizes are used in our harnesses).
    2.) Open up the P0A ECU and cut A11 & A6 and reverse them via internal modification (IE: wires crossing them... see attached picture).

    I chose option 2 because I do a lot of ECU testing and changing my harnesses pinout for one lousy ECU isnt in the cards.

    Anyway thats it for wiring. Go ahead and put the wiring harness back on the car as its much easier to do with the head off.


    Reassembly of head to block:

    Once again we wont dwell here too much, its pretty self explainitory with a manual. Just remember to make sure your
    head bolt holes are clean and the head bolts are clean * oiled with fresh engine oil. Three or 4 stage them down to 78 ft. lbs using the proper tightening sequence. Make sure the bottomend & head were set to TDC properly!!! You dont wanna bang pistons on valves rotating stuff around! I guess the only real advice I have here is make sure that your mating surfaces on the block & head are CLEAN and DIRT FREE.
    Last edited by aero; 02-12-2004, 03:18 PM.

    Intake manifold & fuel lines:

    If you have a 94+ just ignore what I'm about to write about fuel feed & return lines. 90-93 the fuel feed is on the passenger side of the fuel rail, 94+ its on the drivers side. The 94+ uses the same size fuel feed banjo as a 90-93. So all I did was cut & extend my fuelhose (MAKE SURE YOU USE REAL FUEL HOSE) using clamps and bits of stainless tube. Ya, this is a big rig... but my ultimate goal is to get some braided lines made for the car anyway. The fuel return hardline is a little smaller than the 4th gen one, but with clamps it snugs right up too.

    Some other little things will need to be lengthened (read: replace the hose) here and there like the brake booster vacuum hose. Theres just a couple little things like this and will all be very obvious as you're putting the car back together. Also make sure you cap off any unused vacuum lines on the drivers side of the IM... you don't want a goofy idle!

    Timing belt and related:

    94+ EX models use a slightly longer timing belt due to the cam being higher (the head is quite a bit larger physically). So don't even waste time, just go choke up the money for a new belt. This is also an optimal time to replace the waterpump & timing belt tensioner if its been awhile! Slip on the new timing belt and tension it properly according to the published Honda methods. I chose NOT to replace the balancer shaft belt on my engine. People think its risky and maybe it is, but I wanted to see if it would give me a couple ponies... and I think it has. I also used this opportunity to make home-made solid motor mounts for my car (since to properly do the timing belt you pretty much need to remove the front, rear and side motor mounts anyway). Go ahead and check your valve clearances and then button up the cover! As always I reccomend spinning the crank around a few times by hand to ensure it stays in time and that you have no mechanical interference.

    Exhaust and related:

    Pretty self explainitory. I ended up using a 94+ LX header for now because the EX has the O2 bung on the downpipe. With everything else going on with the car I didnt want to add lengthening my O2 wires to the list of shit that could go wrong. Use whatever header you like.. DX/LX ... EX.. or an aftermarket obviously too. The downpipe ended up being like 6" shorter than my old Pacesetter 4-2-1 I had on the car, so I used some flexpipe for now. I'd have something properly welded into place, but why bother when turbo is my goal in the immediate future.

    Throttle Cable:

    The 94+ throttle cables are a tad longer. While you can (and I DID) rig it temperarily, I reccomend doing it right. Replacing the cable is trivial and in the longrun just plain safe.

    Wrapping up:

    Reconnect all of the wiring to the head etc. Your original distributor will fit, so just put it back on! Fill the sucker with water and oil and look around for obvious leaks. Before putting spark plugs in the head I'd crank it over a few times with the starter to put some oil up into the head ... make life a little easier on the cam bearing and all that jazz. Also be SURE that your fuel lines arent leaking. Furthermore I'd have a fire supressor and/or hose around just in case!

    Put in your spark plugs, wire them up... and she'll fire up with any luck! Thankfully when I turned the key on mine I got no CEL's and good oil pressure. Mine popped in about 2 seconds of cranking, I was truly impressed. Obviously let it run for a bit and check for oil & water leaks. While you're waiting for that to happen, nows a good time to check your ignition timing... its GOING to be off since the distributor was off the car!

    If alls well, hop in and go for a ride! Congradulations.

    With any luck it'll finish like this:
    Last edited by aero; 02-12-2004, 03:16 PM.


      Update on the swap: I'll post pics ASAP, but I had to trim the drivers side engine mount back away from the timing belt (The actual cast iron mount that goes from the engine -> rubber boltin mount). The timing belt is tensioned properly, but with all the extra vibration from the balance shafts and solid mounts it was VIBRATING violently enough to actually slap against that mount at times! Didnt appear to be hurting the timing belt, but that worried me enough to grind the mount back about 1/4". Plus it was making an annoying slapping sound now and then. I'm not sure if this is a 4th gen phenomenon only or what, because the timing belt was never that close to the mount before I did the head swap.


        Very interesting.

        Good job man.


          Well I had an actual F22B1 in my Accord before and it didn't vibrate as you stating or need to be ground down. Maybe it only applies to the Head swapped F22Ax. Anyhow, drive that thing to the Dyno and prove something, lol. Probably the most noticeable increases will be your fuel economey and torque gains. HP gains are minimal at best. Good gains over an A1 or A4 but not much over the A6.

          For someone that can do the work themselves and has easy access to a junkyard with good prices this swap isn't a bad idea at all.

          The only thing that sucks about it is the custom exhaust.
          My unupdate website, lol. <click here>.


            yeah..about that exhaust..erm..will I be able to keep my dc sports header i got for my 92 coupe? I REALLY hope so, or else this is not gonna work..

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              Originally posted by Swifty1638
              yeah..about that exhaust..erm..will I be able to keep my dc sports header i got for my 92 coupe? I REALLY hope so, or else this is not gonna work..

              -A. Swift
              No if you wana use the B1 head you need a different header.
              My unupdate website, lol. <click here>.


                seems like a VERY easy swap say if u had a 5th gen and wanted to go B1 instead of B2. that would be easy as hell.. just wire up the vtec soloniod


                  There are a few things wrong with this DIY. I'll let you know my variation when I'm done. In any case, it's not easy whatsoever. It would've been easier to just swap in a different motor.


                    Is it really that hard? I wanted to go to a junkyard tomorrow and either try to find the parts for this, or try to get the ex butterfly parts and such to put on my lx engine. Which do you think I should go with?