Dave WM

I wonder why the grounding of the green wire results in a discharge of the ign module? that is ign "on" engine not running, loosen ground at green wire, and it starts discharging as the circuit is broken. I was contemplating disconnecting it while it was running to confirm the need for the ground being used in my setup. It def does not look factory as the terms look to be home made. Also noted heat shrink on the green and red leads near the block on the distributer side. As if someone replaced the end of the distributer cable. I did check the resistance both at the distributer lead and the ign module. 709 ohms. factory is about 720 so I think at least that looks correct. The distributer internals (reluctor/coil) look VERY clean no way its 45 yrs old so pretty sure something had been done. I assume the HEI swap is pretty non invasive? so if I need to have as an backup I could do something easy.

Can someone confirm if the Green lead at the 2 term distributor block has a ground lead as well as the two green leads connected to it? My 1975 FSM is not clear on this, at least from what I could see in the actual wiring on the electrical chapter. The wiring diagram if I am reading it right does NOT show a grounding of the green lead. However on my car there is one, but it does not look factory. Furthermore if I disconnect it, the ign will not fire. IF I have the ign in the on position and start to remove it (causing an intermittent connect of the green wire to ground) the ign will fire (I can see the spark at the coil and here the injectors firing). Some other testing I have done: observe the ign thru a neon spark tester at the center lead of the dist cap, while cranking I get an inconsistent spark, If I remove the plugs from the car to lower compression (spins engine faster) the spark is consistent (continuous with no breaks). I checked the output of the dist pickup, I get about 200mv AC at normal crank speeds (plugs in). I compared this to my test engine setup that does not have the same inconsistent spark, it also output about 200mv AC. I did not break out the scope yet... I have checked the voltages at the ign coil for correct dropping thru the ballast resistor with a test light and volt meter, full bright while cranking, less once running at the + side of the coil. check for voltages and grounds at the module itself. All this is done since I notice that my test engine always starts nearly instantly while my car always seems to take several revolutions but always starts (not excessive just more, like 2-3 seconds vs a fraction of a second). I was thinking orig that maybe it was a fuel thing but I tested the spark and can see it cranking with no spark then after the 2-3 seconds there is a spark and instant start up. the test engine shows spark instantly with no delay. The battery voltage is good, about 11v under starter load. I even swapped batteries, and both engines sound like plenty of crank speed, The test engine will start easy even when the battery is not it good shape. Its not a big deal as it always starts but I just cant account for the difference in how quickly the sparking (and starting) takes place. My next test will be to try a start with the remote starter while the key is in the on position, just to make sure I don't have any ign switch issues. its a new switch but its an easy thing to check. I did test light checks with the ign module under both "run" and "start" positions, all past fine (full brightness with all leads that should be energized. I check the ground connection (black wire of ign module), it showed nearly zero resistance to the chassis ground. I also used the test light from hot lead to ground lead (just in case it was grounded but not a good ground). While its not much of a load I figured better than a meter. I tried a different module, same results, maybe even a longer crank time. But I can not account for the looks like the extra ground lead on the green wire at the term block. That bothers me.

oh did not know that, did they start using the standard VIN numbers then?

the engine serial number should be on the model tag inside the engine bay. there is a serial number for the body and a different one for the engine, both are listed on the tag.

Guess the main question is why did it fail, yes the video seems conclusive. Hopefully its something like an improper torque sequence, else maybe a problem with the head, only way to know for sure is going to be to open it up and do a very close visual inspection.

Head gaskets whoo hoo, now we are talking fun!!

wheels on, short test ride taken, no shake so far, longer test tomorrow. I like the look of the high profile narrow look of the tires, I think its a closer match to what I remember back in the day when we had a new 74 260z. I know its the opposite of what is in vogue as far as the modern era (low profile as wide as possible tires with suspensions dropped and crazy looking camber) but I think it fits the overall look of the chassis much better. Looking forward to a run to mount dora to check on my pet gator.

Hopefully the cam lobes are ok. Rebuilt head for sure based on how clean it is. Next question besides valve lash and valve damage would be lobe damage. I have heard that using the wrong oils can effect lobe wear. conventional thinking is you want a high zinc content oil. I presume the correct viscosity was well. Lots of discussion on oils so will not re hash it hear, but you may want to do some research on this subject, esp if the lobes are worn.

95% loss, yikes!! and I presume it was from the head and not the block (with that kind of loss you pretty much have to have a valve issue I would think, or a hole in a piston).

ended up at discount tire, Hankook 185/75 R14 T rated. Installed on the steel rims, will take it for a test ride this weekend. Hubcaps should be on the way today from ebay.

I used the phone, but yea facebook is best method. Agreed a website would be nice.

looks like the two in the middle may not be firing at all. Try a power test (disconnect the fuel injectors from the harness one at a time, see if there is any effect on the idle, should be a drop that is consistent as each plug is disconnected one by one. From the look of it the middle two will not have any effect on idle.

going back to OE steel rims, the slotted mags are out. My goal now is to get a original a look tire as I can. I don't race it, or drive aggressively, so really just want a correct look (to me that would be original), with a tire that gets good gas mileage as I like to throw down LOTS of miles..

maybe this https://www.tirerack.com/tires/tires.jsp?gclid=EAIaIQobChMIt7Pl9uC75gIVDtvACh1-8QuaEAQYASABEgIjd_D_BwE&tireMake=Hankook&tireModel=Kinergy+ST&partnum=875TR4H735&GCID=C13674x012-tire&KEYWORD=tires.jsp_Hankook_Kinergy+ST_Tire&code=yes&ef_id=EAIaIQobChMIt7Pl9uC75gIVDtvACh1-8QuaEAQYASABEgIjd_D_BwE:G:s&s_kwcid=AL!3756!3!72322456933!!!g!99873169213!&gclsrc=aw.ds

returned the test tires to JSM reinstalled my slotted mags (while I prep for new tires on the newly acquired steel rims) Shake is back so I am quite sure its the wheels that are causing it rim or tire is still a question, but I have decided to go steel regardless. Next decision is do I get the 195/70 or what ever a 175HR is. the FSM only has the 195/70 with tube, while the 175HR is listed as tubeless. I prefer the look of the wide sidewall skinny tires, so was thinking maybe a185/70 R14, would be a nice compromise. If not I will go for the 195/70 since that is what is on there now, and look ok as far as filling out the wheel well. I am def not in the "lowered" category so really just want what looks like the most factory original I can get.

also, did you ever try removing the oil cap while it was running? normally it should stumble and perhaps die while idling. This will help find if the mixture is set incorrectly as well since unmetered air into the system in a correct working system tends to lean out and die. Again this assume all the EFI is in place and properly hooked up.

The reason I asked if they are carbon fouled was the early post about running rich. Wet does not mean rich, could be just not igniting. I just wanted you to confirm the initial diagnosis that its running rich. Smelling fuel could be a fuel leak somewhere. I like to start with a new set of plugs, then run it for a few minutes, under varying loads if its drivable, maybe put 10 miles on them, and then pull and examine. A properly setup EFI on a 280z should result in nearly white insulators given that test. I just don't want to be chasing a false premise. Poor running could be a massive vacuum leak that may not show up as leaking smoke under the hood, say if its a stuck EGR as an example.

What I meant was are the carbon fouled? Also how is the ign timing set?

have you pulled the plugs to confirm the rich running?

slobber slobber slobber.... :)

I don't know if my slotted alum mags are Nissan OE, I presume aftermarket. I will check my stash of lug nuts and check the fit. I don't recall there being any play, the fitment seemed pretty tight as far as bore and nut size. The way I have to install the wheel is I would place the wheel on the studs, then with just a few turns of the stud beyond the wheel I would start the nuts. Then I would lift and finagle the wheel on to all for studs, sliding it back so its riding on the studs and then tighten them equally to draw down, finish at 90ft pounds. Kinda PITA really esp compared to the steel wheel with the self aligning nuts.

IIRC the guy that did the balance said they all had "some" and he picked the best for the front. There was also a LOT of stick on lead weights he added on some of the wheels... I seem to recall lookin at it myself with a dial indicator on the outer most part of the rim both for run out and out of round, but I don't recall anything jumping out at me. The only other thing I did was replace a couple chewed up studs on the back.

I am sure this has been covered but wanted to share anyway. Since I have owned the car it has had the same tires on it, they were fairly new looking when I go the car a few years ago. The car has always had a slight shake or shimmy I guess you would call it that would cause the steering wheel to shake MOST TIMES around 40-45 mph. That is it would almost always have this shake but not always. After going thru all the front end parts looking for an issue, including take the wheels off and having them re balanced, I finally decided to try some new tires/rims. This dates back to when we had a 1974 260z that did the same exact thing, it came from the dealer with turbine rims (yes we paid for the "upgrade"). After several attempts to resolve a same shimmy in the steering wheel we return to steel rims and the problem when away. Due to the generosity of a member here (JSM) he let me try out some wheels he had been storing. They were steel rim with 205/60 IIRC tires. The tires I had were TOYO brand 195/70. the 60 profile means the diameter of the wheel in quite a bit smaller. After a extensive test drive at all speeds the shimmy is completely gone in my 280z :) I don't know if my alum mag is the problem or the TOYO had flat spots or still improperly balanced, but its nice to know for sure its a wheel issue. The 60 profile tire effected the reading of the speedo quite a bit, 80 indicated was more like 73 actual. I assume the analog speedo is not the accurate to start with but just something I noted (used the gps for actual speeds). The 60s also seemed to allow for a more "pep" as the engine wound up higher, I presume due to the smaller wheels making like a higher number diff ratio. I will still go back to the 70 series though since the look of the 60's just is not right with a 14" rim (just too small over all). I can see how the 70's really need a 3.7 vs the 3.54 diff for a bit more spirited a drive with the ZX 5 speed and its .75 OD. I have correct hub caps coming that should make the car look totally original. again a HUGE thankyou to JSM for letting me try out those wheels, with out that I would not have known for sure the issue without the expense of trying new stuff, now I know for sure.

yea I know the gasket/sealant info is VERY confusing at times. 51813 peratex

when you get around to the front cover, use some sealant all around that gasket. It looks like the same one I used from a rebuild kit, ended up leaking by the shift rod area. I would use the red anaerobic stuff, just a thin film on both sides of the gasket. also sealant on the thru bolts that connect the front cover to the housing.