Login Form

Google Ad

Support / Knowledge

y7/z6 Mini-me swap guide

Pin It
Z6 Mini-Me swap General Overview.
The definition of a mini-me is basically swapping a Vtec head onto a non vtec block. Examples of Mini-me engines are z6 head on an a6 block, or a y8 head on a y7 block. For this guide I will be swapping a z6 head onto a y7 block. The general rule is to stick with the vtec head of the same generation as your non vtec block. I feel however that the z6 head has some strengths that make it a better choice for this swap then a y8 head (the vtec y7 counterpart). The main reason being that it breaths much better then a y8 head.

Getting started

First off, you should know that just swapping a vtec head onto a non vtec block does NOT give you vtec. Since the vtec is controlled by the ecu, your stock ecu does not have the capability to use it. There are a few things you can do to enable vtec. If you are running an obd2 car (96 - 00) I would suggest doing an obd1 conversion. An obd1 conversion on a y7 motor is quite simple to do and will also give you the ability to tune the engine by way of chipping the ecu. If your doing this swap on a obd1 car most likely your ecu can be made into a vtec ecu, however it may be cheaper to just buy a vtec ecu already chipped. Another way to enable vtec is by way of a vtec controller, this is a simple 'switch' that enables vtec by simply applying power to the vtec solenoid. I do not recommend using this method with your stock non vtec ecu however because a different set of fuel maps are used when the ecu enables vtec. Without those other maps not much gain, if any, will be felt.

Ok, now you know what a mini-me is and what it takes to make one work. Now the fun part, you get to go shopping! When choosing a head to purchase, of course always look it over. Check to see if all the parts are with the head, such as the vtec solenoid, cam, valves, the works. Avoid buying dirty heads as it is very hard to look for damage to valves and other parts. If possible select a head that has been washed at a machine shop, and if your really lucky you can get one that has been rebuilt. I suggest if you buy a used head, such as one from a junk yard that you first get the head checked for warping and then get the valves lapped and/or reground. Also it is a good idea to get a pressure test performed on the head to check for any problems.


An easy way to check for warping yourself is to remove the rocker arm assemblies and dissassemble the rocker arms. Then apply some motor oil in the cam jorunals of the head and drop in the cam. Next, without the rocker arms in place, replace the cam bearing caps (what holds the cam in place) and tighten them down. If the cam still turns freely, the head is not warped. You must do this step with the head removed from the engine however because tightening the head down can sometimes remove the warping if it is not too bad. Checking the head for warping is VERY important because if the head is warped and you get it shaved or resurfaced it is then flat on the bottom again meaning the warp will not go away once it is installed on the block again.

Once you have purchased the head you are going to use for the swap I suggest disassembling it completely to check for wear. Completely remove and disassemble the rocker arm assemblies and check for play and free movement. Everything should fit together tightly and move freely without binding. Keep an eye out for metal shavings that may be a sign of trouble. Most of the time however these shavings have come from the bottom end of the engine the head was taken off of. They will however need to be completely removed before you stick this head on YOUR block.

For this swap I needed to purchase a distributor because my y7 distributor is of a different configuration then the z6 distributor. The picture to the right shows the wiring differences between the y7 (single plug) and the z6 (double plug) distributors. It is a very simple modification to make the z6 distributor work on the y7 wiring harness.

Remove the two wire connector and run the black/yellow wire to the empty slot in the main connector. The blue wire is simply an extra signal wire and is not needed. I used a pin from my old distributors connector and inserted it into the z6 distributor. If you do not want to cut up your old distributor you can simply hard wire the black/yellow wire into the cars harness and bypass the plug. If you are using a y8 head on a y7 block this mod is not needed, everything is plug and play.
Next is to make sure you have the correct cam gear to work with your swap. Again, if you are doing a y7/y8 swap this step is also not needed as both cam gears are the same. For this swap I need to use the cam gear that came with the z6 head. As you can see from this picture the teeth do not line up between the y7 and z6 cam gear. This is because the z6 cam is ground different. If I were to use the y7 gear with the z6 head I would end up with somewhere around a 4.7 degree advance in my cam timing. This would not be enough to make the valves slap the pistons, however the engine would not be as efficient. The general rule on this is when changing the cam or head, stay with the gear that goes with the cam you are useing.

Moving on

So your SURE you have all the parts to do the swap? New head gasket, new head bolts (recommended), a change of oil and coolant? OK then.

Start by removing your old head (of course). Make sure you inspect the timing belt for wear if you plan to reuse it. Before removing the belt from the cam gear mark a line on the belt and gear so you can line it up for reassembly. If you are using a new gear you can then transfer this line from the old gear onto the new one. Be careful when removing the belt so that it does not slip around the crank shaft, this will throw the marks off. Clean the top of your block with a rag and even some rubbing alcohol if you would like. Chances are there are instructions on the cleaning procedure with your new head gasket. Note the oil port in the direct center top of your block. If it has an oil jet in it, remove it. My engine (1999 d16y7) did not have one however some do. Vtec will not work this this jet in place, as it will not allow enough oil pressure into the vtec system.

Make sure the mating surface of the new head is also cleaned and free of any deep scratches. I had my head shaved and resurfaced. Be careful when getting your head shaved, as .020 of an inch will raise the compression by about 1 point and also throw your timing off. I found this to work in my favor however, raising my compression to about 10.1:1 and retarding my cam timing by about 1 degree. Yummy compression!
Remove the head gasket from its packaging and carefully line it up on the block. If your gasket has an UP mark on it make sure its UP of course. Now, make sure everything is out of the way. When you place your head on the block you want to do it straight down, do not slide it on the head gasket.


NOTE!

WARNING: IT IS NECESSARY TO MIX AND MATCH HEAD BOLTS/STUDS ON THIS INSTALL! The OEM z6 bolts are 140mm in length, while the y7 bolts are 120mm in length. The reason for this can be found in the back left corner of the z6 head. The head height is 20mm higher for the back corner bolt then the y7 head height. You MUST use a 140mm z6 bolt in this location. Use of a shorter 120mm y7 bolt WILL result in the threads being pulled from the block over time.

I at first used the y7 bolts all the way around but found this to be a problem. To correct the problem I used a z6 and y7 stud kit from ARP. I recommend useing studs over head bolts on any head install.

 

Prepare your head bolts/studs by putting a tiny bit of anti seize on them. If you skip this step you will be kicking yourself later if you ever try to remove your head. Also the anti seize helps lubricate the threads and assures the bolts are tightened properly. If you have the extra cash or if you plan to go turbo I recommend using studs in place of bolts.
Once the bolts are in place you MUST use the proper tightening technique when torquing them. Use a beam type torque wrench and torque the bolts in the proper sequence in the proper stages as shown below.
 
NOTE: The below torque specs are for OEM bolts ONLY! If you are useing studs check with the manufacturer for the proper torque.
Head Bolts

Step 1 .... 14 Ft-lbs
Step 2 .... 36 Ft-lbs
Step 3 .... 49 Ft-lbs
Step 4 .... 49 Ft lbs (Final check)
Camshaft bearing cap bolts

6mm Bolts (ends) 104 in-lbs
8mm bolts .... 14 Ft-lbs
When installing head parts such as the cam shaft and rocker arm assemblies make sure you cover every part with assemble lube. This will assure proper lubrication between the mating surfaces in the first few minutes of running. This is not as important when the parts are already broken in however it is still good to do. Install and torque the rocker arm assembles as shown above.

 


Reinstall the cam shaft gear making sure the crank is at TDC (top dead center), and the UP mark on the gear is at the 12 o-clock position. Some gears have horizontal lines that line up with the head surface. Use a straight edge across the head and check it against the horizontal marks on the gear. I always like to back out the plugs and turn the engine over by hand a few times to make sure there is not binding. If you feel ANY resistance stop and re check your timing belt. The resistance you feel may be valves hitting the top of the pistons.

After everything is assembled I like to prime all the parts with motor oil before I pop the valve cover on. Just to assure oil gets to all the places its needed quickly.

If you have any questions about anything you see here feel free to post them in the form on this web site.

Please Note: It is ALWAYS a good idea to check for proper oil flow after doing this type of work. A simple way it do this is to leave the oil fill cap off during the first start. You should be able to hear the oil bubbling around in the valve cover right away. Within a few seconds (no more then 10) you should start to see oil filling the cam shaft oil well and getting splattered around by the rocker arms. If none of this happenes within 20 seconds of idle SHUT OFF THE MOTOR. Take off the valve cover and inspect. Everything should be covered with oil at this point, the cam shaft well should be full of oil. If everything is still dry, you have an oil delivery problem to the head, which WILL result in damage to the motor.

Quick tip if you do have an oil delivery problem. Before removing the head, take out the rear center bolt/stud and have someone crank the motor over (do not start the motor). Within 10 seconds of cranking, oil should be pummped out of the hole. If not you may have a problem with your block or oil pump. If oil does get pummped up and out, then the problem may be in the head.