Replacing Turbo engine with NA engine

[Jason84NA2T]

COuld be the CAS, but usually when they fail it's an outright failure and not just causing poor running. It's tough to say what it is, maybe your timing belt is off a tooth on one of the cams?

[quote]MachZ wrote:

Have you checked the current engine's compression? How about the MAF?

Lots of people are running 9:1 NA blocks with stock turbo equipment now. As long as you run good gasoline (I ran US rated 93 octane) and set the timing properly you should not have any knock issues. It's really the best of both worlds in my opinion.
What timing would you recommend? I just finally completed this swap last night. :lol:

Stock timing for the year ECU you are using, or a few degrees retarded if you encounter any knock. For instance I never had an issues at stock boost with 17BTDC on a 85T ECU (Which stock is 20BTDC). I was able to run 20BTDC and 12PSI once I intercooled it, but that was at the limit of stock fueling.

[MachZ]

Awesome. I'll put it around there and see how it goes. Thanks!

[Chuck86NA2T]

Jason84NA2T wrote: COuld be the CAS, but usually when they fail it's an outright failure and not just causing poor running.

The CAS can fail and still allow the motor to run. I recently had a distributer that would advance the timing 20-25 deg after it warmed up and even before the timing changed it would jump around a few degrees. When the ignition is good I have always seen the timing hold perfectly steady. After that episode I had a different symptom of the motor running rough under load at times. I finally replaced the power transistor and haven't had any problems since. Remember these are twenty year old electronic components that have been subjected to the underhood heat all their life. I wouldn't rule out the CAS or the power transistor.

[300zxt]

Stock timing for our Z's here is actually 15 degrees, instead of 20 in the US why it's different I dont know but it is...

[William86Turbo]

Oh man that Engine is sweet!, brings back memories of the old days in my friends VL Turbo. Is the rest of the car real nice like that?

I havent as yet been able to set the timing correctly because it is idling too high. Its sitting at 1500rpm at the moment on idle, and the manual quotes the timing to be 20 degrees at 750rpm. I think its to do with the Auxilary Air Control thingy near the EGR valve at the back of the engine.

I didnt realise the timing is different over here. Is that because our cams are the european spec or something like that?

Yeah i was thinking it could be the transistor. I was looking at the CAS today and it looks a little dirty/greasy, but still it looks to be in working order. I guess ill give it a clean. So it could be the transistor too? Im not sure where i would go to get a brand new CAS and transistor.


Before I got this 300 i drove an immaculate 50th anniversary turbo, think it was an 85 model im not sure. It was absolutely beautiful, the most spotless one ive seen round here, had all leather interior, the original log books and all. I couldnt believe it when the guy showed me the original sale receipt. Brand new from the dealership it cost over $40,000. It was one of those lucky Zs that was driven for a year or so then stowed away in a garage. Unfortunately he didnt accept my offer of a few hundred bucks less than what he was asking i think he wanted like $5,300 and i offered him $4,800. The only downside is it was an auto. Sometimes i wish i got it and i would have never had this problem. But It was nowhere near as quick as my one even though my ones not running right.

[300zxt]

Yeah it is tidy outside, but that thing is a purpose built drag car though with a $6,000 2 speed auto custom gear box and all of this other crazy shit.

Your timing could be WAY off and causing you all sorts of dramas. To be honest I really dont know why the timing is different here, I would assume it would be because of the cam differences though as you suggested. 15 degrees is stock for both my NA and 86 Turbo, when I first got my 86' it was already advanced to 25 and it was running SO rich you could smell the fuel and at 20 it's mad fast and not exactly fuel efficient to say the least lol 18 degrees is the sweet spot I've found, in my case anyway for a mildly modded turbo but I'd leave it at 15 for a stock car...

As for that AE you missed out on, I wouldn't be passing up Z31's down here just because of the transmission. They're getting too rare now to worry about that, and infact an engine from a automatic will probably be less thrashed than a manual.

[William86Turbo]

Theres just something about VLs, theyre the best thing holden ever made in my opinion.


I didnt pass it up, I wanted it bad... $4,800 was literally all I had. I even told the guy that it was all I had and he still refused. I think he was thinking yo know nice car + young guy = wrecked car, car crash etc.... which as you would know is not always true... (provided that the young guy can actually drive). lol.

I actually want a 50th anniversary body kit. Like the bumper extensions and side skirts they came out with. I have no idea where to find them.

[300zxt]

http://www.zcarparts.com sell some body kit stuff, and there's always http://proudear.shop-pro.jp if you're willing to pay the shipping costs involved, which are lots. They can type in english but not speak it, they're actually quite easy to talk to via email believe it or not. I asked them about the Shiro lip, shipping is crazy though...

Wait till you have a backyard full of Z's, that's always a good lever to easily buy more off other Z owners at a good price hehe.

[William86Turbo]

When the Crank was at TDC I had a good look at where the cams were. The right hand side one was spot on with the mark above it but the left hand side was out by half a tooth (half a tooth past), So im definately thinking the slack i was feeling was enough to indicate the cam gear/shaft keyway is flogged out from it not getting even operating force. It makes sense because as i said thats the head that I found the wiring not right for one of the injectors. what a pain!.
I think this is the problem but dont know what i should do to fix it.
would this mean the head on that side could be damaged?

[craZed]

William86Turbo wrote: The right hand side one was spot on with the mark above it but the left hand side was out by half a tooth (half a tooth past)

Thats normal.They are all like that.They are just reference points.

Did you put the "L" cam on the drivers and the "R" on the pass. side.

[craZed]

William86Turbo wrote: I recently Changed the timing belt and installed new stock turbo injectors among other things and noticed that the left hand side cam seemed to have an amount of play before the gear actually revolved the cam. I think its because It has been driven so long misfiring on that head (6th cylinder was not firing).

Please elaborate. The gear was turning independently of the cam?
Or the belt had slack in it?

[William86Turbo]

Sorry. When I Originally installed the new Timing belt I noticed when turning the left side cam gear it seemed to have an amount of slack as if the gear was turning independantly of the actual camshaft after which it would stiffen up.
I checked by doing the same to the right hand side and it did not have that same free movement.

I havent touched the cams since i bought the car( I havent removed them from the engine). So they are how they have always been. The L and the R are the right way around. I was just wondering is it possible that the ECU is not the right one? I was looking at the ECU and it has a small round sticker with "84" on it. Does this mean it is out of an 84 model, I guess it wouldnt affect it if it was from a Turbo car... Is there any way of knowing what Year Model the ECU came from or weather its a Turbo/NA ECU??

[William86Turbo]

I checked the power to all the injectors when the accessory power was turned on and found out that one of the connectors was corroded, Ive cleaned it right up and now its running really good, almost perfect.
It idles nicely and low to mid range driving speeds feel normal. When Accelerate hard the turbo spools right up but there is some hesitation with power. I dont think it lies in the fueling system. I am getting a new CHTS and a new Oxygen sensor as i was reading in another thread how they can affect your timing/fuel if they are faulty. Hopefully this sorts it out. Unless someone could suggest something better? Oh ive fixed the timing too. The AAC valve was bad, causing a vacuum leak in the intake manifold which mad the engine Idle higher. so now its set at 20 degrees at ~750rpm.

[Jason84NA2T]

Glad you got it fixed... as for your ECU question, ignore the stickers on the case; they are not the year. Use the ecu model code on the front sticker and compare it to the list on Z31.com to find out exactly what year and model ECU it is.

[craZed]

William86Turbo wrote: When I Originally installed the new Timing belt I noticed when turning the left side cam gear it seemed to have an amount of slack as if the gear was turning independantly of the actual camshaft .

That sounds like a disaster waiting to happen. :?