Decisions Decisions

[Gollum]

So today I picked up a free rebuilt N47 that is supposed to have nissan comp springs and valves installed (springs are obvious, valves just look stock to my eyes. Just needs a cam & lash pads and it's ready to rock.

 

I already have a perfectly good P90 sitting on a shelf.

 

I have a L28ET in a 75' S30 and a stock L28E in a 81' S130.

 

I also have a L28ET block sitting in my garage, short block complete.

 

I'm growing tired of these motors, but I just somehow keep collecting parts for them. I'm kinda stuck with the inline 6 to some degree in the 81' due to smog, but I'd been debating putting carbs on it since I've only been getting around 22mpg on average anyway. I know there's something wrong, but other than low compression I can't find it. I know the EGR isn't opening all the way, so maybe I've got low vacuum somehow?

 

At any rate, I'm kinda stuck debating what to do to make use of all this stuff I've got. The new N47 is in great shape, obviously fresh from a machine shop, and the guy that owned it NEW datsuns and I trust him whole heartedly. Decades of master tech status for multiple companies, he knows his stuff and loved Z cars.

 

So here's some ideas I've thought of (please give me your ideas too, just remember that I'm not blowing the bank here)

 

 

Idea 1:

Take the turbo block and put the N47 head on it, get a semi wild street cam in it and put it in the 81'. I can either find a carb manifold, and figure on swapping it out every smog time, or I can build an EFI manifold and megasquirt it, or I can take a die grinder to the head to accept an OEM intake maifold and pray I can diagnose any problem on the existing EFI (which won't be happy with the new cam)

 

This idea would then allow me to take the flat top piston block, rebuild it, and take my P90 sitting around and go to town doing what one can in his own garage. I could then put this new turbo engine into my 75', or another Z down the road.

 

Idea 2: Take the new head and put it on the same spare block, but then just throw it into my turbo car as an odd turbo combo. I could then take that motor out of the 75' and put it into the 81' and maybe eventually put a turbo on it (I know the engine currently in the 75' is in great shape). The only problem with this combo is that I'd need to make an intake for it, since the N47 doesn't have the injector provision. This isn't exactly bad though, as I've wanted to anyway. I could find a 240Z cam and throw it in there, and once megasquirted it might make for a pretty nice street getup.

 

 

Idea 3: Take the new head as a gift from God, and sell the damn thing, along with all that I can L engine related. Put a low mile KA24DE in the 81' and keep the L28ET in the 75' until I find the time and money to do something I really actually want, like a VG30ET or VQ35DE, or LS1, or KA24DET, or 5.0, or anything else that's cheap that I don't have to worry about blowing up until well after 400 wheel HP.

[Josh280z]

If your frustrated with your EGR, take the EGR off. Im pretty new to my ZX, but I dont like look of all the EGR systems, so i plan on removing them anyways.

[NewZed]

Can't really help you with your decision. But I thought that the N47 did come with injector notches since it is a late model head. Below is a quote by 1 fast Z from a thread on cylinder heads. I have an N42 head on an EFI 76 and an N47 on an EFI 78 myself.

 

Just trying to clarify for you, and make sure I know what I think I know. Even the 75 head should have injector notches.

 

"N42= This head came on all 75-76 and EARLY 77 cars. It has the 47cc chamber, and this head is a

fully open head. This head was used on a fully dished piston, to where no quench was used. It has the

largest of the valves much like all 280's did. 44mm intake and 38mm ex. This is the last of the L heads

that came with bronze seats. This head has Square ex ports, and has the Injector notches as well.

 

N47= This head came on all mid 77 through the 1980 z cars. It has the same exact characteristics as the

N42 except that it has the cast in ex liners. These liners were cast in place, for the reason that when the

motor is running, these liners get so hot that they glow red hot, and with that you get the advantages of

them burning off the hydrocarbons that are left over in the exhaust charge. This is the first head to have

hardened seats put in all of the valves."

 

http://forums.hybridz.org/index.php?showtopic=62691

[Gollum]

I guess I'll have to check it again, I thought I was pretty sure it was an N series head that wasn't setup for fuel injection. Maybe I'm wrong though. I'm positive at any rate that it's NOT setup for fuel injection, thus would need to either be ground to take injectors, or I'd have to use a custom manifold with injectors further up stream.

 

And the EGR isn't bothering me on my 81', but for what ever reason I'm not pulling enough vacuum to operate it is why it barely passes smog. I've removed EGRs before, but do LIKE to pass smog here in CA even if the visual is completely false. Having someone test a different car as mine is just too much work, honestly.

[KillerBjt]

Gollum, if you wanna get rid of those L6 parts ill take them off your hands

[Brad-ManQ45]

You can't go to carbs - won't pass visual.

 

Low compression=low vacuum.

 

My '83ZXT didn't pass emissions 1 year, so I replaced the O2 sensor and it passed.

 

 

I had just put in a 3" exhaust from stock downpipe back w/3" cat, new plugs, wires, rotor and cap and was surprised that it didn't pass.

 

I found out later, after it had passed, that the EGR was not working at all - there was a plate made out of the top of a tin can between 2 gaskets holding the EGR valve to the intake manifold - effectively blocking off any gasses being passed.

 

All by way of saying that you don't need EGR to pass - fix your other problems.

[Gollum]

Oh I now the compression is low, it needs to be rebuilt. It's got over 220k on it now and hasn't had an easy life.

 

I never need to worry about visual passing. I just don't want to have to find a spare 280ZX around to REALLY cheap the system. No thanks. And I know from previous testing that I'll pass just fine if I hook a hand vacuum pump to the EGR. The theory is that if I had a good solid bottom end, with carbs that there's the chance I could get it to pass the sniffer.

 

 

And no worries killerbjt, locals like you will get first dibs on all my L series stuff if I sell it all. I hate dealing with shipping parts long distances.

[primer&rust]

Megasquirt can be a whole box of new problems, at least it was for me and I had a professionally assembled unit. I'm dealing with SU carbs now and even though they have some lean spots (I'm going to order some SM needles) THEY ROCK! I'm getting lots more pull than the injected engine and they start so much quicker than the fuel injection ever did. If you need more compression and you have some money or a machineist friend get the head milled to its max limit shim the cam towers and that should raise your compression some. All the N47 heads I have seen along with N42 p79 and p90 head are setup for injection or carburetion. I think the E heads didn't have the notches and thread bolt holes for the injection manifold.

[Gollum]

So it's a N42 head. No injector provision, square exhaust ports, open chambers. Still no pics, sorry.

 

Right now I'm strongly thinking about just putting this head on my spare bottom end and throwing it into my S130 in some fashion of which I'm not sure yet. But that should help some of that car's problems, and it deserves it. Then I can figure out what to do from there. For my S30 I'm thinking I'm going to go LS1 but I'm not sure how and when yet. But putting the engine together for the S130 shouldn't cost me hardly anything, just the price of gaskets and my time.

[Gollum]

Instead of starting a new thread I'm going to bring this one back, since this is the topic it's regarding.

 

So I still have this wonderful N42 sitting here, and every day that goes by I realize I just don't want to get rid of my S130. And to make it so much worse, my smog buddy whom I grew up with had gone into a different avenue of mechanical work, but is now doing smog again. And now he's training my brother to get his license as well! So I won't be in short supply in help getting my cars to pass.

 

This winter then I'll be building up a motor with my parts on hand with the N42 and turbo block. Should get me compression over 8:1 and enough grunt to get me around. The tough decision still is this damn fuel injector issue. I either have to grind the head to fit the stock EFI manifold, or I have to convert to a carb'ed setup, or go with a custom manifold. None of these options sound all that appealing to me honestly. I'd love to make a custom manifold, but I don't want the added EFI costs on top of that. The carb options looks really good, but they're not exactly cheap either unless I just want to hunt for some junkyard SUs and rebuild them. Taking a grinder to the head just seems like such a waste as the head was freshened up by guys that know a heck lot more than me about these engines.

 

The other option would be to find some flat top pistons and rebuild this turbo block and put my spare P90 on it. The head could use some love though, and I could have it shaved while getting it cleaned up and looked over. I'm not looking for a 250+hp hot street motor, just something to get me around (even 150 at the wheels would be more than enough). Might spring for a nice header and exhaust down the road. Keeping it simple should keep costs down, but the benefit of keeping the stock EFI setup would be saving the money spent on the rebuild, pistson, and machine shop work I'd be having done if I shop around enough. On the same token though, I really don't like the stock EFI and have only had problems with it concerning my S30. So maybe going carb'ed might be the better option for me, if I can score a good deal.

 

 

As always, any input is appreciated. I've got all summer to figure this out. In the mean time maybe I'll try my hand at fiberglass this summer and shed some weight off this baby.

[KillerBjt]

Well Gollum, i have 2 carb manifolds and 1 SU carb. Yes 1. The carb is unknown condition but its probably repairable if broke. I'd sell them to you for pretty cheap.