1990 USDM CRX Si D16A6 to ZC SOHC non-VTEC swap, help

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Hello everyone,

New to this forum, but not to Honda's or CRX's. I've done some wrenching on my current car over the past 6 years (minor stuff only), but I'm now swapping the motor and need some help. I've searched both this forum and the internet in general, and am more confused than when I started. The stats:

Car - 1990 USDM CRX Si
Current Motor - D16A6 1.6L PGM-FI ODB-0
New Motor - SOHC ZC (non-VTEC) 1.6L PGM-FI ODB-1 (is ODB-1 correct?)

Reason for the swap - The current motor has 211K miles, blew a head gasket at 140K miles and was fixed at a Honda delaership. Car has been slightly overheating during hot days with the A/C on since the repair, but for the past year it's been burning oil and coolant. And now it's really bad, D16 won't last much longer. I think my head was just slightly warped after the HG blew, and Honda didn't fix it properly. I have confirmed low compression on cylinders 2 and 3 (1 and 4 are within spec).

Monday I ordered a ZC SOHC non-VTEC from ACE in LA, and it arrived yesterday. Here's what I plan to do:

- Swap the intake/exhaust manifolds from the D16 to the ZC (will have new gaskets for both).
- Keep the current Si transmission and move the flywheel to the ZC (and putting in a new clutch)
- Swap the main belt pully from the D16 to the ZC (motor came with a Power Steering pump, taking it off and swapping the pully because the ZC one is rusted)
- Install new water pump, thermostat and timing belt on the ZC
- Swap the Cooling Fan Switch connector from the ZC to the Si wiring harness
- Use the alternator from my D16

Now here's where I'm confused, as I have found conlicting info on the net. Could someone here please give me definitve asnwers for the following:

1. The ZC did not come with a Distributor. Can I use my D16A6 Si distributor on the ZC? If not, do I have to get a dizzy from an 88-89 Integra?

2. Can I use my Si ECU, even if I have to change the dizzy, or must I swap that too?

3. Anything else I need to know about this swap?

My niece's husband works for a Honda/Toyota repair shop, and he's been working on Hondas for several years, so he's going to help me do the swap. But he's also stumped on these questions, and none of the shop manuals cover swaps. ;)

I'd like to get the swap done in a single day, so the more prepared I am at the start, the better. So I'm trying to gather a list of all the parts I'll need to get this done to avoid driving back and for to the parts dealer, or trying to find stuff online.

Thanks in advance for your help.
most SOHC ZC non-VTEC engines are OBD0 - it was available in OBD1 and OBD2 also, but most are OBD0 - first, you need to identify which you have - if it is OBD0, then swapping it into your Si is just like swapping another D16A6 in - the engines are identical except that the ZC has a little better camshaft in it - other than that, it is the same and uses all the same parts as the D16A6

if it is OBD1, you need to change a few things wiring wise, but you should convert it to run OBD0 - this is the easiest way to do it

the OBD0 enigines have white distributor connectors and white injector clips - they turn a little yellow looking with age but they are white - the OBD1 engines have dark gray connectors instead of white - the OBD0 distributor has a round 7-wire connector - the OBD1 has a rectangular 7-wire connector

determine if it is OBD0 or OBD1 and get back to me - i can tell you everything you need to change (if anything) in order to make it work - we have swapped somewhere around 2 dozen SOHC ZCs (along with at least 50 DOHC ZCs) over the last 10 or 11 years
OK, thanks for the info. It might be hard to determine what the ZC is as it came with no dizzy, and all the wiring was chopped. Not sure if any dizzy wiring is still on the ZC. But I think most of the other connectors I saw were all dark grey, whereas most of them on my D16 are white.
Forgot to add, if the ZC is ODB-1, what dizzy will I need (I assume my D16 dizzy won't work), and will my PM6 ECU work?
OK, thanks for the info. It might be hard to determine what the ZC is as it came with no dizzy, and all the wiring was chopped. Not sure if any dizzy wiring is still on the ZC. But I think most of the other connectors I saw were all dark grey, whereas most of them on my D16 are white.
doesn't really matter that much which it is - easy to convert it to OBD0 - the OBD1 just has a few things that are different which you need to address

OBD1 has the cooling fan switch on the thermostat housing instead of the back of the block - should have the MAP sensor on top of the throttle body - should have a rectangular grooved fuel rail instead of round - uses a 4 rib alternator belt instead of the 3 rib that OBD0 uses
you said you are swapping the intake manifold? why?
if it is OBD1, you will also need to swap the driver's side engine mount that bolts to the end of the block from your D16A6 to the ZC - use the A6 timing belt covers as the hole for the mount is different on OBD1 than on OBD0
OK, thanks, that's something else I'll look at. So if the motor mount is the same as the A6, then the motor should be ODB-0? Or will I have to look at the connectors as well?

From what I looked at the other day, it seemed the drivers side mount was the same as the A6.
Drat my inability to edit posts!

I wanted to add that I'm also pretty sure the connectors on the fuel injectors are dark grey, so who knows.
OK, I see now. I have to have at least 15 posts before I can make edits to my account and get the full features of the forum. So here's adding another post to my count. ;)
this is the OBD1 SOHC ZC non-VTEC - the biggest visual differences are the intake manifold, throttle body, fuel rail, crank pulley, cooling fan switch and gray connectors - visually, the OBD0 looks exactly like your D16A6, except it probably wouldn't have the Fast Idle Control Valve on the back of the intake manifold , toward the driver's end

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OK, then I definitely have the ODB1 version. It looks exactly like that, except mine did not come with a dizzy or MAP sensor on the IM.

I pulled off the Power Steering pump, and will switch out the IM and EM from my D16. Which dizzy will I need?
Oh wait, you said I could use my Si dizzy if I kept it ODB0. Is the firing order different for the ODB1 ZC than the D16?
Oh wait, you said I could use my Si dizzy if I kept it ODB0. Is the firing order different for the ODB1 ZC than the D16?
use your Si engine harness, distributor and ECU - firing order is the same - if you use your Si intake manifold and injectors, nothing changes there - you will be using the MAP on the firewall and nothing changes there - as i said before, you will need to swap the driver's side mount from the Si onto the ZC - the part that bolts to the block and extends thru the timing belt cover - they are not the same - the only change you will need to make to the wiring is for the cooling fan switch - it is on the back of the block on the Si (2 wires with big round black rubber boot) - wire colors are one black and one yellow with green stripe - on the OBD1 engine, the cooling fan switch is on the thermostat housing - you need to swap a 2-wire connector (rob from the OBD1 harness if it is there) onto the Si harness and plug it in - wire colors should be the same but it doesn't matter which one you connect to which as it is just a switch
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Dont make fun of me but what the hell do you guys mean by dizzy?????
distributor - i don't like the term "dizzy", so i always spell out "distributor" - using terms like dizzy, tranny, etc. makes it very hard to search for things regarding the actual items - the search function on most forums is hard enough to find things with even if you use the correct terminology - one of the worst has to be D-series.org, which no matter what you enter, you seem to get every post made on the forum whether it has anything to do with what you are searching for or not
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That's true. I usually don't use those types of terms either, but I've gotten tired of speelling out distributor lately. :p
Oh, and thanks for all the help and advice. I'm conflicted about the distributor because I've heard both that I can us the Si one, and that I need to buy the 88-89 Integra one. I'll stick with the Si for now and hope it works.