NewZed

It's the amps that produce the heat. It may be that the 78 igntion module flows too much current for the Crane coil. The PS60 shows a primary resistance of 0.4 ohms on their page (below). Compare that to the 78 Z spec. of 0.84 - 1.02 ohms and you can see that a lot more current is flowing through the whole system than the 78 module is designed for and maybe the Crane coil also. The coil may be designed to have more resistance in the circuit. You're probably lucky if you haven't fried the Z ignition module. The description says compatible with all OE electronic ignition systems but the 78 Nissan system might be a little too primitve. There's more to designing an ignition system than just matching primary circuit resistance but it is one important factor, just to keep the heat down. I'm an electronics rookie and probably always will be but I wouldn't even change the 78 coil specs. without "upgrading" the module also. The modules are over 30 years old and crapping out on a regular basis. Putting more work through it can't be good. http://www.cranecams.com/416.pdf

From Post #9. It seems to me that one of the original problems was that the cam is bent a small amount (as pointed out in another forum also), since the binding is not consistent across 360 degress of rotation, it's only there for 20 degrees. That's what I meant to look for, in one of my posts about measuring cam "run-out", although that may not be best word for it. Just trying to help you avoid more pain in the future. As has been pointed out, there's a certain sequence to follow to end up where you want to be.

Old-style brake cleaner (chlorinated), MEK, ethyl acetate, acetone, THF or nail polish remover should work. The new environmentally friendly brake cleaner might work, I don't know what it's made of. Mineral spirits paint thinner probably not so good, not polar enough (chemistry term, sorry). http://www.loctite.com.au/cps/rde/xchg/henkel_aue/hs.xsl/3286_AUS_HTML.htm Near the middle of the page.

Looks like the downloadable EXTRA code does spark mapping. Maybe that's the "EXTRA" part. http://www.msextra.com/doc/ms1extra/MS_Extra_Basic_Configuration_Manual.htm#desextra http://www.msextra.com/doc/index.html

Not to jump in front of PMC, if he even intended to reply, but is the head bent top to bottom or side to side? You seem to describing a side to side bend. Why would you use the manifold mounting holes otherwise? The plan doesn't fit the original problem. As far as fixing the "fixed" head - how thick is it now, from bottom surface to top surface? After all of the trips to the shops it has to be getting thin. Measure at each corner to get an idea of how parallel the surfaces are, just for fun, to see where you're at. Do you have the "How to Modify..." book or just the "How to Rebuild..." book. There's two books, and they're different. The straightening process is in the "How to Modify". I'll copy the page if you want to try it or show it to one of your shops, although it might be too late.

Search 280z blue springs on Google. There's at least one informative hit on the first page.

The early 280Z's used more pins/wires than the later ones. The later 280Z's had the pins in the AFM for the fuel pump contact switch but don't use them. Check the FSM for the wiring for your year of car, you should be able to figure out if you have the wires that you need. Edit - I overlooked the "75" in your title. If your EFI system is stock, you'll need those extra wires for the fuel pump contact switch. You'll need seven. Weirdly, for you, I think that even the 280Zx uses five.

Check (measure) your fuel pressure, and fuel flow for starters. Might be low.

Flip the level over and measure again. Do the same on the bottom of the head. Make sure the head is of even temperature throughout, cold on one side hot on the other will give some bend although I have no idea how much. There are much better tools out there for those measurements and many people here who know how to use them. I'm just throwing some basics out. You don't trust the shop? Didn't they tell you how "straight" the head was, or how much they cut? Didn't they have the cam towers to measure from since that was the ulitmate goal? This story gets weirder and weirder. Edit- actually, considering the whole thread, the real issue/question seems to be how much it would have cost to have it bored (line- to align, or align-, whatever your preference) and whether or not you could find a shop that knows how to bore aluminum camshaft bearing brackets (towers), (as opposed to steel crankshaft bearing journals). It seems easy in principle, so why didn't any of the "machine" shops you've been to suggest it. Seriously, if you took the head in to a shop and said "my camshaft is binding, how do I fix it", it seems like a shop with some experience would have measured camshaft run-out, then suggested a fix. It's odd that you haven't found a shop that can just look at the head and its parts and offer a fix, even if it's expensive. How can this be so hard?

Rubber bushings between the bar and the cover are a bad idea, I believe. The diff has a lot of leverage on those studs. Not clear how that could work. Didn't the early 70 240Z's use a different front mount and bar? The whole short driveshaft thing. Sounds like you have an early 240Z front mount which has the diff mounted forward. Just a guess, I never got in to all of the details of the early 240Z forward-mounted diff.

I can't recall seeing it done but it seems like you should be able to measure the voltage pulses on the power wire from the ECCS to the transistor, while cranking the engine. The HEI module will need that to work, just like the stock power transistor does. If I had the problem I would connect my meter from that wire to ground, crank the engine and see if the ECCS is doing its thing. It might be so fast that a meter won't pick it up though. Unless you've seen a working signal, and know what to look for and how to measure it, it might not tell you anything, if there's no measurable signal. On the other hand, if you see the pulses, it will be a good sign that the HEI module should work.

The two metal prongs that you see when you unplug it. Doesn't matter which probe is on which side.

Testing the CHTS is super simple, it's not even hard to reach like on the thermostat housing mounting position the 280Z use. It's right there. There's a chart of resistance versus temperature in the FSM. There's a lot of other info in there too. At least you'll know if you have the right one.

Let me know and I'll send you the row numbers as I recall them from memory, and what I heard. You might have to do some hunting.

There are a few 5 speed 280ZX's in the Portland area PicknPulls - North, South and Sherwood, and one in the Vancouver yard. They don't show up online though. Might show up in their in-store computer. If you know someone or ever get down that way. http://www.picknpull.com/default.aspx

I hope that you said "parallel" also. Based on your experiences to-date, it could be important.

You didn't really ask a clear question unless you're lloking to make it run better at low RPM. I would define fairly low.

If you read around the internet, which you've already done, then you'll find that getting a good fit when swapping towers seems to be hit and miss, after lots of trial and not-working. Some have reported that they swap tower positions when trying to get things to work. You might even trying mixing and matching towers from the two heads and spinning them 180 degrees. Who knows. Nissan says to junk the head and get a new one if the cam towers are damaged, they don't have even have an option for making new towers work. In the factory's view, onced the towers are installed and line-bored they are part of the head, never to be removed. So there is no machine shop procedure to fix the issue. It's luck. Have you tried the damaged P90 cam in the P90 head? You have two heads and three cams right? The P90 cam with the cracked dowel hole might have the best odds of success.

You only mentioned the rear control arm bushings. Unless yours are degraded, you might not notice a difference if you only swap the rears. The factory rubber bushings, when in good shape, are actually pretty tight. At least they were on my car, a 1976. I didn't notice much when I swapped the inners. I swapped my bushings a piece at a time to gauge effect. Changing the bushings up front, especially the steering rack and TC rod bushings, will have bigger effects on handling. Other bushings, like the mustache bar set, will effect noise and shifting feel. Lowering the car will have a really big effect on how the car handles. It will feel much tighter and less top-heavy. My general impressions. The rear control arm bushings are the last that I would do if I was starting over. Actually, the inners were the last I did and I never did the outers. Swapping that thin piece of rubber for a thin piece of urethane doesn't seem worth it.

You could have had it running and blown up by now, and been on to another head. You know it's going to self-destruct anyway. Just run it.

Good point on the daul cone, I forgot about that. Otherwise, though, I think that the single baulk ring synchros are exactly the same. On the clutch, don't forget that after the swap the trans has an L6 bellhousing. The only clutch part bolted to the trans is the slave cylinder and it's still bolted to the same L6 bell. So there's no need to change any of the clutch parts.

You might be able to find it here - http://nissan4u.com/parts/info/43244A0800/ And order it here - http://www.courtesyparts.com/screw-p-359474.html I picked a "screw" but don't know if it's what you're looking for.

This might help. There are parts inside the rear drums that typically need cleaning and adjustment also. If the parts work right, the rear brakes adjust automatically.

Didn't mean to kill your thread. Here's one, re the 16 mm shift rod hole - I used a 16 mm drill bit and a drill press to very carefully enlarge the shift rod hole to 16 mm. It was too small and the shift rod bound up during test-fitting. So I used an aluminum rod, some scrothbrite and zip ties, and a hand drill to hone it out until it worked. I don't think it needs to be super accurate, the shift fork itself is pretty loose on the coupling sleeve.

You might have damaged the seal in the master cylinder. Apparently, the rubber seal can get damaged when it travels over areas that haven't seen a seal in a while. Look in the reservoir while someone presses the pedal and see if the fluid is going anywhere. Careful when it comes back it might squirt out of the reservoir if the cap is off.