Zed Head

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.

Is it off yet? My suggestion for removing the head with manifolds attached was short on details. Don't forget to build a wedge for the timing chain, unless you'll be taking the front cover off again.

That's a great writeup, but if you have a hoist to lift the assembly it's also possible to remove the head with the intake and exhaust manifolds attached, along with the fuel lines and injectors. Disconnect the AFM and the injection wiring harness and various vacuum lines, and the exhaust pipe at the flange, then remove all of the head bolts, including the two that bolt to the front cover. Lift the head and manifolds as a unit. It will also allow you to use the manifold as a handle to break the head and gasket loose from the block if they need a little help. Just another option to consider. It's a lot easier to get to the intake and exhaust manifold nuts with everything out of the car. If you don't have a hoist and you're planning to just lift the head off by hand, then weight reduction becomes a consideration.

I don't think that you'll be able to adjust that away. The rocker on lobe #9 sounded really loose also, which is cylinder 5 and also had low pressure in your test. Looks like bent valves. I vote for removing the head. Just one vote, but let's see what the prevailing view turns out to be. Hope that there's no serious piston or bore damage.

Don't forget that idle air/fuel ratio is meant to be controlled by the idle air screw on the AFM. Before you get too carried away with the spring (again). Idle performance is its own little world. There are really just three fuel control areas to worry about - idle, part throttle and open throttle, and only two are really tunable, idle (air screw) and partial (AFM spring). Open throttle is "full enrichment" and will be fuel pressure and injector flow-rate dependent, so can't really be tuned in. There are many other causes for a rich mixture and/or dirty plugs. TPS adjustment, water temp circuit resistance, leaking CSV, leaking injectors, worn rings (oil fouling) are possibilities.

Just registered for me what you meant by arcing from center to negative post. Brain not working right earlier. Still bad, but beerman and SteveJ have the solutions.

Hey, I mis-wrote above. The coil sparks when the ground to the negative post is broken, not made. So the spark jumping to the negative post shouldn't happen unless you have a short in that wire or it's jumping to ground farther down the line. Maybe you have a pinched wire in the distributor.

Not good. Your E12-80 module won't like those voltage spikes since it's on the end of the negative post circuit. You're blasting a lot more voltage through there than it was designed for. How close is the coil negative post to the distributor cap and/or its center wire? That might be the source of the problem. Sounds like it's too close. The spark you're seeing happens when the module grounds the coil negative. So it makes sense that the coil negative post would be a good path to ground. Easier to go there than jumping two gaps. Could also be that your center wire isn't seated completely. That would be three gaps.

How do you know the leak is at the interface between the throttle body and manifold? Have you checked the BCDD? It has a gasketed mounting surface also.

Where exactly is the contact? Is it tire on springs or wheel on tower? I don't see how you could hit the tower without the tire hitting the spring first. Maybe your initial test fit was without tires, or tires with a different profile. As far as the spacers go, I think that if you have sufficient stud length extending through to get good clamping force they should be okay. You might have to install longer studs to be safe. Your wheelbase might be wider or narrower depending on the offset of the wheels subtracted from the offset induced by the spacers. Back to zkars #8 post - maybe the hubs are different in form/appearance, but not function. Same offset and bearing race dimensions, but no effect on usage. By the way, your photo bucket account requires a password to view.

Just realized that a bent valve could also have lots of lash clearance if it's stuck open. olzed's right, spend some time on the easy stuff first. Also, you could always disable three cylinders and just run on the remaining three for a while. olzed has some tips on how to do it.

That's a good point, a head swap might work also. Assuming/hoping, no head bolts break, and that there's no piston or cylinder wall damage. But overall, an engine swap might still be the quickest, most effective way to get on the road. Just because the engines are relatively cheap and easy to remove and re-install. Lots of options, for lots of skill levels. First thing to do is remove the valve cover, and examine the moving parts. You can check lash without loosening any adjustment nuts. A bent valve will probably have zero clearance. Actually, the first thing to do is to download the FSM and read the Engine Tuneup and the Engine Mechanical sections. The first will describe lash measuring and the second will describe what's involved in removing the head. Post some pictures, everyone likes to see damaged parts that aren't their own.

The valve lash adjustment procedure is described in detail in the FSM, Engine Tuneup section. It's a standard maintenance item. But, since you probably did not adjust the lash before you changed the timing chain, I would say that you have some bent valves, based on the 0 and the 58. You will probably notice something different about the way the tops of the valves look on cylinder 2, and maybe 3, when you take the valve cover off. If you don't know how to adjust valve lash, it seems that you got way ahead of yourself when you decided to change the timing chain. If you want to drive the car any time soon, you might be better off to pick up a used L28 and swap it in while you figure out what to do with your damaged engine.