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Discussion Starter #1
CONCEPT-Using a newer generation D16Z6/D16Y7/D16Y8 1.6 block with a PM3 casting D15B7/D16A6/SOHC ZC head.

REASON-Need a replacement head on your 1.6 equipped Civic utilizing a non D16A6 block.

DISCLAIMER-This conversion may not be legal in your area and as such you, the owner, assume liability for any issues, be it legal or mechanical, that may arise from running this particular combo.


The following will be based on the D16Z6 block combined with a D16A6 head going into an 88-91 Civic. The write up in general should apply to the D16Y7 and D16Y8 blocks as well with minimal variation with respect to the modifications performed.


GETTING IT MOUNTED INTO THE CHASSIS​
The block will fit together with your existing transmission and matching flywheel/clutch/pressure plate assemblies. For the driver's side engine mount you will need to use the mount and bracket that is meant for your car. The following will demonstrate why...

The first picture is with the Z6 mount and bracket in place and the second picture is with the A6 mount and bracket in place. Note that the mount is farther forward when using the A6 mount and bracket.






MATING THE HEAD TO THE BLOCK​

As I recall the 88-95 Civics all use the same head bolts so if you are using a D16Z6 block simply reuse your head bolts (not recommended but I know people do it, myself included...once :p). If you are using a 96-00 D16Y7/D16Y8 block you'll need to do some checking on your own. I know that there is a difference with one of the head bolts being a different length but I don't know how that will come into play with the PM3 head. If no one else can confirm which bolt combination to use for this setup I'll eventually get around to it via the junkyard and update things here.

Next up, you have to deal with the oil control jet. As with most (if not all) VTEC motors the oil control jet is located in the head while the majority of non VTEC motors have it located in the block (this holds true for most D, B, and H series motors). For this specific combo you'll realize that both the block and head do not have an oil control jet. This means that you will have to obtain one seperately. Easy enough but here's the problem:





As you can see from the measurements taken, it will not fit in the block. You have two options to make it work:

A.) Take an appropriately sized drill bit and open up that hole with a depth deep enough to accomodate the oil control jet. I only recommend doing this if you have the block out of the car and have the oil pan off. The last thing anyone needs is metal shavings being circulated in engine oil.

B.) Shave the oil jet down to fit the existing opening in the Z6 block. If you want to be precise have it done at a machine shop. Afterwards you will need to source an appropriately sized o-ring for the oil control jet.

For my setup, I chose to go with option B for two reasons. The first and primary reason was because I had already put my block in my car and sealed the oil pan. The second reason was because I didn't want to permanently alter the Z6 block. Since I was on a budget I opted to do shave down the oil control jet myself by inserting it into a drill and using some sand paper and a sanding stone as shown:





Hold the sandpaper (and sanding stone or whatever you are using) to the oil control jet and let loose with the drill.



After about 15 minutes or so, I was able to get it down to a workable diameter. If you do this yourself take your time and make sure you use a micrometer. Go slowly, once you shave off material there is no going back!

 

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Discussion Starter #3 (Edited)
For the o-ring, I measured the diameter of the o-ring seat on the oil control jet and took a trip to the local parts store and bought a generic pack of metric o-rings. I matched an o-ring that had the same inside diameter measurement as the seat on the oil control jet. The problem here is that the thickness of the new o-ring would not allow it to fit into the block. My solution, repeat the drill process and narrow that o-ring down a bit. You want to leave enough material on the o-ring so that it will fit snugly into the block.









Now that the oil control jet is addressed, you'll want to decide what you want to do about the compression. For my situation I was trying to make a combination close to a stock D16A6 so I let that dictate what I needed to do. If you don't already know, the P28 piston found in the Z6 block has a bigger dish than the PM6 piston found in the A6 block. If you are shooting for a straight A6 compression like I was you have two options to achieve the 9.1 compression ratio:

A.) Use A6 pistons.
B.) Shave the head down.

For my situation (at the time this was done anyway), swapping pistons wasn't an option due to budget constraints. Instead I opted to shave the head down to achieve the 9.1 compression ratio. Here's is where a compression calculator comes in handy:

Honda D-Series Compression Calculator by ZealAutowerks

Using that link, I found that when using the P28 pistons in combination with a Z6 metal headgasket the head would need to be shaved .030in to obtain a comparable compression ratio to the A6. So I dropped my head off at the local machine shop and had them take off the appropriate amount of material:



For your specific setup and/or needs use link above to figure out your course of action. Please note, although it is not included in the picture you should obtain an adjustable cam gear to compensate for any mechanical timing difference due to any amount that the head has been milled.

By now you should be ready to bolt the head down to the block.

THE TIMING BELT​


The next challenge I encountered was finding out that the Z6 belt was too small and that the A6 belt was too loose. Solution? Use a DX timing belt.

A6 belt - too big!!


Z6 belt - too small!!


B2/B7 belt - just right!!


Before tightening down the tensioner you should be sure to swap out your stock cam gear for an adjustable cam gear if needed and adjust as necessary to obtain the correct TDC position for the camshaft being used.

Something worth noting here is that the B2/B7 share the same tensioner as the A6 which unfortunately is not interchangable with the Z6 tensioner. I tried to mix and match tensioners to try to get either the A6 or Z6 belt to work and found out the hard way that they only fit their respective blocks. I don't know if the D16Y7/D16Y8 tensioners are interchangeable at this point with one another or any of the other engines so you're on your own if you want to try and mix/match things there. Another point where you may potentially adjust slack in the belt is the water pump. I'm not sure where I saw it but I believe certain ones have a slightly different diameter on the drive gear but it is such a small difference that I doubt it will make any substantial gain/loss with respect to tension on the belt.
 

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Discussion Starter #5
TIMING COVER​

Now that the belt is addressed, you are ready to put the timing belt cover on. Again, like the tensioner, the covers only work with their respective blocks. I thought simple, use the Z6 timing cover because I'm using a Z6 block...not that simple. This made me ask two questions, 1) Will the Z6 lower cover work with the A6 upper covers? and 2) Will I need to use the Z6 pulley since the timing marks are meant for it? Well, since I had both an A6 and Z6 block at my disposal I compared the relevant aspects and this is what I found:



For question 1) I simply mocked them up and found that they hit each other.


Solution? Cut the top portion of the Z6 lower timing belt cover. You could trim the A6 upper covers but I figured I'd rather cut on piece rather than two pieces. I trimmed along a ledge that was already molded into the cover. Turns out that it is almost just the right amount to cut off to make it work with the A6 upper covers.





And now for the test fit:

Sensitive content, not recommended for those under 18 Show Content


Seems to fit just fine now, you may have to experiment if you are using a D16Y7/D16Y8 but I imagine it's going to be nearly the same.

So now on to question 2). Again since I had both parts, this was as simple as setting the block to Top Dead Center (TDC) with the original Z6 pulley and then swapping it out for the A6 pulley.

With the Z6 pulley:


With the A6 pulley:


Seems to be the same so timing it will not be an issue. Once again, for the D16Y7/D16Y8 you'll need to verify that marks are the same (16BTDC +/- 2). If it is then you should be good to go.
 

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Discussion Starter #6 (Edited)
THE FAN SWITCH (88-91 Chassis only)​

Assembly from here on out is straight forward but there is one more major difference that will need to be addressed. The thermoswitch for the radiator fan is located on the back of the 88-91 blocks while on the 92-95 engines it is actually located on the thermostat housing. Unfortunately they do not use the same switch or the same connector.

Back of the A6 block, the thermoswitch is the two pronged green sensor:


A6 thermostat housing, no sensors:


Back of the Z6 block, no thermoswitch but you can see the place for it is still physically there on the block but it is not drilled thru and it is not tapped for threads:


Z6 thermostat housing, the thermoswitch is the only sensor on it:


I looked up the radiator fan wiring diagrams for both the 88-91 Civic and 92-95 Civic and found that the diagrams were basically the same thing so I went ahead and cut the old connector off of the harness and replaced it with the corresponding connector (I also added an appropriate amount of extra wire to extend the plug so it would reach the thermostat housing).

I referenced my 94 Civic to confirm I was cutting the correct plug off of a spare harness I have and double checked it against the wire colors found in the FSM. The plug for the A6 harness had one yellow/green wire and one black wire while the plug for the newer harness had one green wire and one black wire. Simply cut and solder the new plug.

Picture from my 94 Civic to confirm the correct plug will be cut:


My spare harness:


The plug needed:
 

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Discussion Starter #7
The plug cut from the harness:




Test fit:


Extended wiring:


The connector to cut from the harness in the car (plug should have a cover/shroud but mine didn't):


New plug soldered into place on the harness:


Connected:




After EVERYTHING was addressed, I assembled my motor using new seals/gaskets as needed and filled the engine with new fluid after letting it sit for a day (I wanted to ensure enough time had elapsed in order for the hondabond to fully cure. I turned the key and it fired up on the first try.

Any questions feel free to post. Hope this helps someone out in the future.


NOTE: This took alot longer to type up and I'm tired so I may edit this tomorrow to fix any grammatical and/or spelling errors and to add any relevant info I may have missed.
 

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the only thing I can think of is not recalibrating the timing for the shaved head. you should be a couple of degrees off from center on the cam. roughly a half a tooth off. I'd get an adjustable gear to dial in the cam timing with this setup as it will help with tuning in the future. but rep for the info
 

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Discussion Starter #10
^Kinda goes without saying (well maybe not to people who haven't done something similar) but yeah, my mistake for not including that. Thanks for pointing that out :TU:
 

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Ok so I have a z6 block and zc head project going on right now and using the b7 belt right now.... My problem I'm having is we get it in time and after a couple hand turns the cam ends up retarding and hitting valves.... What exactly do you have to do with the timing???
 

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WOAH! I see calipers and creativity! )(#*$)(#*$ Awesome!

I would not have cut and spliced wires like that, as it may have been easier to just de-pin and run the wires from the spare harness to the new location.

But, NICE!
 

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:eek:fftopic:
can someone please do a "UN-PIN - RE-PIN" wire harness write up...

you guys make it sound so easy lol
 

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Discussion Starter #18
Waterfordmaxx-I don't know what to tell you other than practice makes perfect. I used to run into the same issue and found that if I leave the cam at TDC and align the crank somewhere just before the ignition timing marks, when I rotate the crank to put tension on the belt that extra slack is just enough to let the crank rotate to TDC before it puts tension on the belt and starts to pull on the cam. Give it a try.

4Door-It's really hard even with pictures to do that write up as it's more of a specific "feel" than anything else. When I first did it I wasn't able to do it for about 10minutes because I couldn't feel the tiny clip with the tiny screwdriver. After I finally new where the spot/feel was it only took a few seconds to get the rest.

The Acid Beaver-Looking back yeah I wish I depinned that plug but I didn't have my tiny flat head screwdriver available and time was an issue (deadline) so I did what I had to do.

acexxxoasis-I wasn't really looking to explain this part but here it goes...

As stated to Acid Beaver, I was under a time limit/deadline. A "buddy" of mine kept talking about a "monster" D-series build that he was going to undertake. I was skeptical of his plan and challenged him to a race to prove his theories. The basics of his plan revolved around a 92-95 Civic hatch with a D15B7 engine and a Z6 transmission. He kept running his mouth about a A6 cam or a mini-me conversion being the fastest thing on earth (well not so much but the way he talked about it...that's the way it came off). Me and HIS buddies and some mutual buddies doubted his abilities and his theories. So we gave him a deadline to "build" whatever he was talking about. I have a 91 hatch that at the time wasn't running (blown DOHC ZC, R.I.P.) that was awaiting a new engine. I had both a complete Z6 and an A6 at my disposal. I put up the extra challenge to him, decide on what he was going to put together and I run the equivalent stock version AND beat him on the track. His A6 cam in D15B7 vs my stock A6 or his mini me conversion against my stock Z6. He decided on A6 cam in D15B7 so I was going to swap in my A6 engine. Here's where the whole thing went wrong for me. I took apart my A6 for inspection (used off of craigslist) and found that the walls were ovalized real bad, to the point that you can see the pistons leaning to the side midway up. I didn't have money or the time to have an overbore done but I did have a complete Z6. So to keep things relatively the same I asked if I could use the Z6 block for the challenge and that's why I didn't just do a complete Z6 swap.
 

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Discussion Starter #20
We never raced, the whole time he was running his mouth he never did anything to the car. After I asked to use the Z6 block he started saying I was cheating and that he was going to shave the head on his mini me conversion and do that instead of the A6 camshaft swap. He cried alot about what was unfair so I said fine do what you want, I'll run the A6 as is. Another friend suggested to just do whatever, forget the rules and just build what you can. So we agreed but turns out I was the only one actually working on my engine. If you notice in the pictures I'm not using the stock manifolds on there. He was saying he was going to do the CG transmission and do P29 with .060 shaved on the head and blah blah blah so I was like whatever man. I took apart my ZC transmission and mix/matched the ZC gears with Si final drive, shaved .060 off my own head by mistake, and assembled with bolt ons and chipped ECU. Deadline came but he had a family member pass away so we postponed until he said he was ready. After he stated his own new deadline, I figured we were good to go for the challenge but no he missed his new deadline. Later I found out that maybe a month before the original deadline he was trying to sell the car but he kept saying he was doing this and that to it to meet the deadline. He was never serious, just instigating a bunch of BS. Sucky part was I was unemployed at the time and it took a lot of saving just to do what I did (and I had no intention of doing it either, I was content with putting the car as NON-OP at that point).

Oddly enough, I ended up doing almost exactly what he was supposed to do to my daily driver. 94 hatch, 1.5 block 75.5mm pistons, .030 off PM3 head, Z6 intake/exhaust manifolds, A6 camshaft, HKS sport exhaust, Injen 3in short intake and an Si transmission. As good as that combo feels, it doesn't compare to the engine pictured above. Maybe you can call that a win but we'll never know. I may take my daily to the track just to see what it does and compare it to what I've already ran on the A6 head/Z6 block combo pictured above.
 
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