Zed Head

Wade's on a roll, it's hard to keep up... Rock Auto - http://www.classiczcars.com/forums/thread46074.html Edit - but it seems the sub $25 price is only for the later Zs. Which is odd considering a previous discussion about whether or not the 240Z and 280Z hubs and rotors are different. Edit 2 - Still not sure that they're different, not sure why Rock Auto has two parts and two prices... http://www.carpartsmanual.com/datsunS30/DatsunZIndex/Axle/FrontAxle/tabid/1728/Default.aspx

The ECU provides idle enrichment fuel when the TPS is on the idle circuit, independent of the AFM vane position (as I understand things). Could be the AFM, that's where I would start looking. You can remove the black cover on the side without removing the whole AFM and look for corrosion on the carbon trace or contact and/or spray it with some contact cleaner. If it looks okay, you can also check the connection to the wiring harness, underneath. The AFM will have to come out. You'll need some kind of pick to get the wire spring retainer off, it's a little bit difficult. You might also check fuel pressure beforehand though if you have a gauge available. Should be done anyway after eight years and probably easier to do than removing the AFM. Edit - cbuczek brings up a good point about timing and the distributor, that could save some future aggravation. If you start taking things apart, take the distributor breaker plate off and make sure that the ball bearings under the plate haven't rusted to the bearing surface. They get stuck, then the plastic frame holding them breaks when the vacuum advance tries to move the plate.

I haven't experienced it myself, but I get the impression that these engines will idle without the AFM connected, although your car should have a fuel pump relay switch in the AFM that won't allow that. Have you checked the AFM and its connection? Seems AFM or TPS related. A little more detail on "bogs out" will help your quest also. Could mean many things.

I think that the cam mark in that position would actually be advanced, and it's about where it should be according to the FSM (the "after adjustment" position). Was the timing mark exactly on the zero, and did you get it that way without backing up the crankshaft? If you rotated the engine forward then nudged it back to hit the TDC mark, the slack in the chain wouldn't pull the camshaft back with it. I had a coolant leak on my last engine, at the back of the head. And an oil weep at about where your water leak is. Barrs Stop Leak might fix the water leak, it helped mine but it eventually came back.

You've described the "after" but haven't said much about "before". How did it run before you installed the header? How long did it sit between the last time it ran and now? If it runs but not smoothly, it could be something simple like a misplaced plug wire. And the running rough problem might be totally separate from the odd noise.

If you have extra hose, you can put a loop in it. I think that I have loops on both sides of my fuel pump. It makes for a nice stress-free connection at the pump also.

Not my idea, but packing grease around the perimeter of the piston will allow you to do some grinding without getting the chips where you don't want them. Pack the grease in, do your work, scoop the grease out with the chips embedded. I think that I read about it from people doing valve reliefs in their pistons.

You might consider getting a used head or used engine to use while you figure out which way you want to go. All four options described above will give a different type of car. The engines are surprisingly durable compared to 70s domestic engines, and used parts still have a lot of life in them, even with lots of miles. You could probably get back on the road for under $200. I bought my car not running because I thought I might put a V8 in it. But after I got the stock engine running well and drove it around, I lost the urge. A V8 car is a totally different beast. By the way, I think that you'd get more feedback if your thread didn't have the huge pictures in it. I don't even want to open it anymore because it takes too long to load all of the images.

Coincidentally, this thread came up on another site - ECU question - HybridZ Referencing this page - XenonS130 - ECU Information

Thanks mjr. Kudos are hard to come by... Good luck with the car, it's not exactly clear what exactly you fixed though. Was it just the timing being off and a vacuum leak? Bad distributor? Just needed a good tune-up?

Since you're in the United States, I would take a look at this car - datsun 280z trade for 510 clean title Cheaper and looks in much better condition. Right down the road too...

Still seems odd that someone would put flat-top pistons in an N42 block, then use the stock 78 ECU and AFM, when you can get the pre-assembled setup by buying an 80-83 ZX engine. But, apparently, some people feel the N42 block is made of better metal (higher nickle content?). Or maybe a PO had some P79 pistons laying around and needed to get it running. What did your receipts show? Any comments about new pistons? Seems like you might have three options: 1. Get a P79 or P90 head to go with the flat-tops, to get a more stock CR of ~8.8. This would be the factory stock 80-83 ZX engine, essentially, and could probably run well with your stock 1978 ECU and AFM. It might take some minor tweaking but the engine was not much changed from the 75-79 Z engines. 2. Old school with carburetors and a hot cam. This would be mainly mechanical tuning with jet changing and timing adjustments, etc. to get things working right. There are lots of people on this forum that know carb tuning. 3. Modern aftermarket EFI, like Megasquirt or Haltech. This route would be more electronic with tuning by computer, and could be as simple as adjusting just fuel through injector opening times alone all the way to controlling timing through a crank angle sensor along with fuel requirements. It would require a computer and more hardware, but could give you more flexibility, with enough electronic gismos added, like IAC controllers, and O2 sensors, etc. Here's a link to browse if you want more insight in to what's involved - EMS - HybridZ Don't forget to check the emissions testing requirements for your car in your state before you get to far.

The engine long-blocks (block, pistons, head, etc. no manifolds) should be essentially identical, with P79 heads and flat-top pistons, if they are both NA, not turbo, engines. But the various valves and gizmos on the intake manifold, and the distributor, and the AFM, might be different enough to use a different ECU. You might try to find the part numbers for the ECU and the AFM out on the internet world and see if they are different. Or you could look through the Engine Fuel and Emissions sections of the FSMs and see if the functions of the ECUs are different. I would look at the Electrical section also and see about any timing changes in the distributor. The early 80s distributors ran a ton of vacuum advance to go along with the EGR, and somewhere in there they started using a temperature and vacuum switched, dual timing control for the advance. The 80s were the age of emissions control so there are all kinds of interacting devices on the engine. If you're lucky, they stabilized for a little while on one ECU and AFM setup for your two engines and the changes were elsewhere. Probably sounds more complicated than it is, a look at the FSMs will tell a lot. XenonS130 - S130 Reference

I'm guessing that the seller has no idea why the car won't start and just came up with this out of thin air. If you were selling a car and knew that all you had to do was replace a fusible link to get the car to run and draw a much higher selling price, why would you not do so? Three red flags - car doesn't run, electrical system has been replaced, and seller comes up with WAGs about what's wrong.

That might be a sign of an ignition problem. You have a bucket full of problems.

Without either the circlip or snap ring off, the front half of the case is locked on to the shaft by the main shaft bearing. Heat around the edges of the front cover along with some PB Blaster or similar will soften up the gasket material. I think that the back half should still come off though, not sure what's happening there. I actually had problems keeping the back half on when all I wanted to remove was the front half (bellhousing). Edit - also just realized that I've actually taken three transmissions apart, two partially, one completely. For what it's worth...

The snap ring catches people sometimes as zKars says. The snap ring is external to the bearing, in a groove on the outside of the bearing race, keeping the bearing in the case, and the circlip keeps the bearing on the shaft. If you just take the the circlip off, you'll be trying to pull the interference fit bearing off of the shaft. I've only taken one trans apart, but that's what I did, the bearing ends up in the front case. It's a slip fit in the case though, so it will come right out when the snap ring is removed. I've also seen a few accounts where people couldn't get the back half off (like you're describing) without using a dead-blow hammer or a block of wood on the ears of the back case (tail-shaft housing). It needs some shocking in the right direction to get moving.

Funny, but the 36 psi with the engine running could be an indication of your FPR going bad or the vacuum line to the FPR missing or leaking. The vacuum line from the intake manifold should drop the pressure to at least ~32 psi, even with poor intake vacuum. Could be the whole problem or just one part of it but I would get the FPR working right as one "to-do". ~38 psi with hose off, ~32 psi or less with the hose on. With good intake vacuum fuel pressure can get down to 28-30 psi at idle. Edit - changed 36 to 38 psi. The FSM calls for 36.3 but most of the FPRs seem to regulate at 38-40 psi with no vacuum hose attached.

I think that he means that he can't see the gear inside the transmission, or when he inserts the speedo drive asembly it doesn't turn. The 5 speed hold down slot is on the opposite side for the later 5 speeds. You could actually grind a new hold down slot in the drive assembly and get it to work. Put it in with the slot on the opposite side and see if it catches and turns. It would be odd for the gear to be missing entirely.

Odd that a 27mm thin wall won't fit. If it won't, what will? You might be able to get it to turn by wrapping the fan belt around the pulley and using it as a handle. You can get quite a bit of leverage that way. Or use a strap wrench on the pulley. The handle would give you enough leverage. http://www.amazon.com/s/ref=nb_sb_noss_1/190-1806788-4353652?url=search-alias%3Daps&field-keywords=strap+wrench

Maybe you're on the other side of the ratio - extra-rich. Is the exhaust all gassy? Plugs moist? Have you measured fuel pressure? Maybe it's high.

It's not a huge deal. Just something to consider when buying parts, piecing things back together, making decisions or tuning it afterward. You just have a non-stock setup so the factory specs. might not work the best. If you're not in to the tuning and modifying side of things, it might not be a good situation for you. There are several members of this forum who run the N42/flat-top piston combination. Start another thread with "N42 head and flat-top pistons" in the title and you'll probably get lots of suggestions. I've only tuned the stock combinations so can't speak with authority on your combination. I would dig through the receipts though and see what's been done. Might be some more interesting stuff in there.

The N42 block came in the 1978 cars,but the factory head was an N47, same as the N42 but with exhaust liners. The pistons should be dished, but those in your pictures and video are definitely flat-tops. So you don't have a stock 1978 setup. If the head has not been modified you'll have around 9.8 compression ratio. Depending on where your timing was set and some other considerations, you might be close to the detonation threshold. Maybe that timing chain noise was engine knocking? Who knows, different people get different results. Some people have no problems with higher CR, some people have to back off the timing. Flat-tops and an N42 head is not an uncommon combination. Anyway, your engine is not stock for 1978. Somebody has been in there messing around before you got it. Good luck with it.

Leaving the exhaust manifold hooked up - that's another way to do it... It might be just the camera angle but those look like flat top pistons and the exhaust manifold looks like it has the later ZX style diamond shape. Do the exhaust ports in the head have liners? Does the head say P79 or P90 on the passenger side, above the 1 and 2 spark plug holes? Does the block have F54 molded in to it down by the driver's side motor mount? You might have a ZX motor in your 1978 Z. Might be important for parts.

Sounds a lot like the fuel pump cutoff switch, which your 75 should have. With a big vacuum leak, less air goes by the AFM vane, it shuts, opens the contact switch, and kills power to the fuel pump. On Starting the switch is bypassed, so you get another 3 seconds worth of fuel pressure. If you need to keep the engine running so that you can find the vacuum leak, open up the idle screw to get more air past the vane. It will have a high idle though. Or take the cover off of the AFM and tweak the thick wire that opens the switch to keep the switch closed. Have you checked the hoses to the AFM, the breather hose from the top of the valve cover, the oil filler cap and the dip stick tube? All possible leak sources. When I first got my car I did the recommended FSM test of pinching the AFM hose with the engine cold and running and split the hose lengthwise, because it was so old. Couldn't see it but I could hear it.