Tennesseejed

1. Check you local parts store for the thermal sensor. I found one for $16. 2. The coolant bypass connects from the thermo housing to the vertical tube on the doo-hickey shown in picture 7. I found hose at the local parts store. Don't recall the specific size. 3. With a two bolt thermo housing (which it looks like you have), the only hole with enough meat around it to tap the 3/8" NPT GM sensor is the thermal sender hole. If you haven't already, download the Megatune/Tuner Studio bundle from DIY Auto and see which sensors are listed under the Tools/Calibarate Sensor settings. The MS software comes with several thermal sensors pre-loaded. It's up to you to figure out the thread sizes for each sensor. And herein lies your potential problem using a two bold thermo housing - If the GM sensor will only tap into the thermal sensor hole, then you will not have a dash temp gauge. I know because this is how it went for me the first go. The second time, I purchased a three bolt thermo housing and, surprisingly, the GM sensor went into one of the holes without tapping. I use two sensors, thermal sender and water temp guage. The other holes are blocked. 4. You can also run fan control using your MS box. Using the Honda sensor for direct control is fine, providing you don't need this hole for the water temp sensor. 5. I don't know what size threads the side hole has. Sorry. 6. No idea what that sensor is. Looks like something off a '78 or a ZX. Did not come on my '75. 7. Check the Parts For Sale forum. You should be able to find one of these from someone parting an engine. Don't know what the proper name is. I'd describe it as some sort of coolant collector. FSM digram might have the name, or call a parts store and see what their computers call it. 8. Don't know the answer to this, but they have 12mm bolt heads. The best advice I can give when setting up a thermo housing for MS is to decide what water temp sensor you are going to use and where is it going to be located before you do anything else. And don't do what I did, which is to tap the thermal sender hold for 3/8" NPT because you won't have a dash temp gauge. Sorry I couldn't answer all your questions. Perhaps someone else will chime in. Good luck.

Mike, I'm pretty much out of ammo, but let me tell you what I think I know. First, your car should eventually start regardless of whether the cold start injector is firing or not. During cold start operations the cold start injector only adds extra fuel until the themotime switch opens the circuit. I can't imagine it's that cold in Colorado in August. It was 70degF in Anchorage today. I downloaded the '78 FSM from xenons30.com because there are differences between the '75-'77 and '78 years. I own a '75. The '78 FSM shows Pin 21 on the EFI box being used for the cold start injector circuit. Pins 19, 20, and 22 are not used. Are you sure you have a '78 EFI box? Because Pin 21 is used according to the FSM. ??? Second, the cold start injector should have 12VDC with the key on the "start" position. After the engine starts, the cold start injector should continue to have 12VDC from Fuel Pump Control Relay and will continue to have 12VDC so long as the engine runs. Only when the thermotime switch heats up will the cold start injector cease to fire. At least that is the way I read the '78 FSM. Final thought is that your fuel pump should not be running while the key is in the "on" position and the car is not running. I don't know how, or if, this might be related to your no start condition, but it is a nontypical condition. Actually, one more question and a thought - Are you running MSD6 yet or the still the Jacobs ignition? And don't worry about your tach operation until the car starts reliably. The tach does not affect operation of the ignition or fuel injection circuits in any way. Worry about getting the tach to work correctly later.

Should clarify my last post - I used the 8910 adapter, not "4910". Looking at a '77 wiring diagram, the tach and EFI Pin 1 are both fed off the Coil (-) Blue wire. If you switch to MSD6 you should not need both adapters. There are at least two ways to fire OE EFI with the MSD box. I used the 8910 adapter in series with the Coil (-) post and the blue wire (Red wire to post/White wire to Blue wire). Can't say it was the best possible solution, but it worked well. The 8920 adapter is normally used in between the MSD tach out pin and either Pin 1 or the blue wire upstream of the tach resistor. I have never installed an 8920 so not much help there. Search the Ignition subforum for MSD6. There are several somewhat confusing/helpful threads. I did find MSD tech help to be pretty helpless when I called. I'm still using MSD6 with a MSII fuel only install. It works well enough that I'm having a hard time finding the energy to upgrade to MS3 and attempt sequential spark. Though I probably will next Spring. Currently my MSD6 box is located behind the passenger firewall on the floorboard. Not ideal. The unit can also make a fair amount of noise. If I were to install MSD6 again - or just get off my butt for 30 mins - I would (re)install the MSD box inside the windshield wiper bay. I learned that someone on here had done that after my install was finished. I have a spare 8910 adapter if you interested. Send a PM. Edit: Given the current driven 240Z tach, you may need both adapters after all.

I'd wager that the source or your problem lies in this paragraph. If you don't already know, look into how the Jacobs Electronics CD ignitions operates (I have no clue). The stock L28 operates by maintaining a constant 12VDC on the coil and the ICU (ignition control unit) operates the sytem by dropping the voltage to ground which, in turn, sends a signal to the Pin 1 on the EFI box to send fuel. Until your last post, I was sort of assuming that your reference to "ECU" in the first post meant you had installed the stock ICU. Now I understand that your are using ECU to refer to the EFI box. I ran into this problem when I installed my MSD 6A box. The MSD unit does not maintain constant 12VDC on Coil. Instead, the MSD system sends a positive pulse to the coil upon an ignition event. Using the MSD 4910 adapter I was able to "trick" the EFI box into reading the stock signal. I don't know much about the stock 240Z electrical system other than I loved the '70 I took to prom and the '73 I owned after High School back in the day. I do know that the 240Z tach is current driven off the plus side of the coil as opposed to the 280Z tach which is driven off the negative side. Given that your original post indicates that you have installed a 280Z EFI harness, I'm not sure this relates to your problem, but you should consider whether any of the original 240Z wiring is related to your problem. If your Jacobs unit is a negative voltage ignition unit (does not provide constant battery voltage on Coil +), then you should focus on finding a way to drive the EFI box as your solution. For example, the MSD box has a tach out pin which can be used to drive EFI. Although I did not use tach out to drive my MSD installation, it also requires a tach adapter. Does Jacob Ignition have a support page that would help?

Have you verified that Coil (-) is connected to Pin 1 on the EFI unit? Do you have 12VDC on the injectors? If the injectors aren't firing, the two most likely culprits are lack of power to the injectors or lack of signal to the EFI box to know when to fire the injectors.

Do you know if the '78 280Z and '81 280ZX use the same model dash temp guage? That is the only thing I can think if that would make a differnce in which housing to use. The two sensors/signals you'll need are CLT for MS and the existing thermal sensor if you want the dash guage to work. I'd probably go with the '78 housing just to eliminate the potential problem of differing guage styles. I recently did a fuel only MS install using the existing harnes on a '75. Before the install I read the thread you linked. With respect to the author of that thread, I found it was easier to sit down with the wiring diagram from the EFI bible and do it myself. The wires in the EFI harness are numbered which helps a lot. And if I can be of any assistance to you, feel free to PM.

on a '75 280Z - and I see that you have a '78 280Z so this may not be helpful - the easiest solution would be to put the switch across Pins 36 & 39 on the air flow meter. This way, the fuel pump is tricked into thinking the car is running while the key is in the "on" position.

Were you able to get the engine to turn over? I'm not familiar with the 240Z or 208Z inhibitor circuit so I'd suggest circumventing it, if possible, until you can get the car running. Pin 76 on the fuel pump relay powers the starter solenoid. Unless your starter is not wired properly to battery+ & chassis, you're probably not getting 5VDC on the starter solenoid. Check the solenoid lead with the ignition on start as well as Pin 76. If you don't have voltage there, you've got a different problem.

Looking for the back half of a FS5W71B gear box. Only need the case.

Check the map sharing thread in the Megasquirt sub-forum. It's a sticky.

That's the thermal transmitter. Single wire out that operates the temp gauge on the dash.

I'm running MSD6A with MS. The MSD box tach-out triggers MS and then I use IAC1 (tach out) to run the stock 280Z tach. My only complaint with the MSD box is that it can be pretty noisy. Currently its located under the floormats on the passenger side. Originally, I ran MSD in lieu of the stock igntion box. The wiring isn't very difficult, but I needed the MSD 8910 adapter to run the stock EFI box. Wouldn't say that adding MSD is a major performance upgrade, but you'll notice smoother idles and perhaps a little more top end. Definately better than the stock ignition box, IMO. Car is '75 280Z.

I was referring to the EFI Bible which can be found pinned in the Troubleshooting Section. Though a few prayers and hymns before you turn the key might help as well.

I'm currently running MS fuel only on a '75 280Z. When I went to a stage III cam, I really didn't have a choice but to ditch the OE FI system. I also bought all the EDIS stuff, but plan on going straight to sequential/COP when more MS3 units are available. In deciding whether to install MS, you should consider your ultimate performance goals. A performance L6 is an expensive build and only a few guys on here eclipse 250hp - and I think one of those is running triples. If you don't ever plan to rebuild your engine or install a performance cam, you might save both money and headache by not bothering with MS. My MS install was actually pretty easy. Tuning was the more challenging part. I used the stock wiring and mounted my MS box in the same place the OE FI box is located. You just use the FI wiring diagram from the Bible to find out which wires are which. The wires at the OE FI box are numbered too, which made things really simple. Since I did a top end rebuild at the same time as the MS install, I can't tell you what improvement you can get by MS alone on a stock engine. To answer your last question, if you do decide to go MS, I would install it and have it running before you do any other major engine work. For example, you might get a little nervous (as I was) when you are supposed to break in your cam (15 min. @ 2K revs) at the same time you are trying to figure out how to get MS started and running well enough to tune.

Zmanco, you're not getting a lot of responses here so I'll nibble. I'd look at your dropping resistor values. I read your post over on msextra.com and still am unclear about what size resistors your using. 3 Ohm or 6 Ohm? 3 Ohm would be low. I assume you wired your injectors as alternate banks on MS. I.e., three injectors each bank. If you haven't lately, check out the info on www.megamanual.com. Specifically the "Injector Resistor" section under "Injectors and Fuel Supply" which is about halfway down the page. Low resistor values result in higher current. I = V/R so current is inversely proportional to resistance. I.e., as resistance increases, current decreases, and vice-versa. Using low value resistor means that when the MS grounds the injector circuit to open the injector, high current flows through the circuit. If you have PWM on your version of MS, I'd recommend trying a 60% setting the next time you're are at the track. I would more or less simulate doubling your injector resistors without having to muck around with wiring.

I stand humbly corrected. Glad BRAAP could send you in the right direction. Good luck.

JSM, I don't have the answer to your question. I'm just trying to be helpful. Your OP said "test" on page 45 so I thought you were referring to a specfic circuit test. Perhaps you meant "tests". As you know, Pin 35 on the ECU is a ground (for '75 anyway). You can easily confirm this with a mulitmeter to see if you measure little or no resistance from Pin 35 to chassis ground. I do not know for certain, but seriously doubt, that the L-Tronic FI system was radically changed between '75 and '78. Is there a specific test you are needing, or are you just generally asking if the November 1975 EFI Bible will cover your '78?

Page 45 of my copy of the bible is the list of circuit tests titled "Circuit Testing." Typo???

Thanks for the reply Zmanco. Correct. I was originally going install EDIS, then MS3X came out. I couldn't find a MS3 board to buy, so I'm going to run fuel only and transition to sequential fuel and spark down the road. Even so, I was getting no tach signal in Megatune or Tuner Studio. I had tried MSD tach output without sucess. What I did incorrectly, though, was to wire the tach output to Pin 2 (sensor - ) and not Pin 24 (sensor + ). After your response I wired the MSD tach output to Pin 24 and was able to get the car started. Thereafter the car ran - badly - for about 5-8 minutes at very high idle. I've got a mechanical timing issue because my friend was not able to see the timing mark while the car was running. I'll tackle that tommorow.

I installed MSII (v.3.57) yesterday in my NA '75 280Z. The car has a Stage III cam and stock bottom end. 240SX throttle body. GM IAT and CLT sensors. No MAP sensor. LC-1 wideband installed. Fuel algorithm is set Alpha-N. I am trying to run fuel only off of a coil negative trigger. Ignition is MSD 6A. I have spark. Plugs are dry. I have comms with the MSII box and have burned a startup .msq including all of the known variables. Req_Fuel is 10.9 on turbo Z injectors. TPS tests correctly. Sensors have been calibrated (though my IAT temperature reading is 30 degreees high). When I crank (set to 300), I do not get a tach reading on MegaTune. I have tried different variations on wiring the MSD 6A box. I have not wired MSD 6A according to Megamanual because I am not using MS to run ignition. MSD 6A is triggered off of dizzy VR and is wired to drive the coil directly. Tried using the MSD 6A tach output to signal MS without success. Despite searching, I have not found in the literature what signal MS is looking for when triggering on coil negative. I suspect it looks for 12V going to ground when an ignition event happens. And I believe the problem is that the MSD box does not put 12V on the ignition coil until an ignition event. I ran MSD 6A with the stock FI box using a MSD 8910 adapter last year. However, this set up does not effectively trigger MS. I am also uncertain if I should to use "Fuel Only" or "Basic Trigger" in the Tach Input/Ignition Setting box. I'll try to attach start up datalogs, but right now I'm getting an error that says I can't upload these kind of files (XLS). Appreciate any thoughts. Edit: I wired coil neg to Pin 2 on DB37, but did not wire the positive side to Pin 24. Is this required? There is very little in Megamanual about running fuel only off of a coil negative trigger. The stock FI box ran off a coil neg input only, so I didn't think MS would require wiring Pin 24.

You might refer to the '81 or '82 FSM if the Haynes manual is a little vague. I think the site is XenonS30.com or something like that. I recently replaced a timing set and degreed a cam on a '75 which is probably similar since they share the same block (but not distributor). I agree with goldfish that you should verify TDC first. With a piston stop, its a very simply process. If you have a dial mic you can also verify your cam timing while your in there. If your engine has a lot of miles, the timing can be advanced using the stock cam gear. With regard to advancing the distributor timing, I believe that looking down on the distributor shaft you would want to move the shaft one gear clockwise. The '75 FSM describes the proper shaft position to be 11:25 (o'clock). Might be different on an '81. You could also count the number of gears on the dizzy shaft sprocket and divide that number into 360. That would tell you how many degrees moving the shaft one gear will advance (or retard) the timing. Best of luck.

I have removed/installed two transmissions using a floor jack. Perhaps I was particularly lucky, but if you go slowly and spend enough time looking at various angles, it is virtually effortless. Now the rear shaft flange bolts . . . well, that's a different story.

I'll be getting Megasquirt and accessories. Might buy some EDIS-6 hardware as well.

Well after a pretty serious battle with the flu, I finally managed to get back into the garage and work on the head. Not much new here, but did want to post an update that it might help my fellow novice head builders. Here is a pic of rockers with the final wipe patterns: When I was getting started I wasn't sure how to mock up the lash pads to test the wipe pattern. After a few moments of serious MacGyvering I came up with a solution. These boxes are shim stacks to set valve lash on dirt bikes (my YZ450F in particular) and the shims come in thickness from 1.2mm to 3.5mm. These shims fit nicely between the lash pad guides and make it a breeze to adjust the wipe pattern by using shim of different thickness. With regard to the two troublsome rocker pivots, after chasing the threads a few times, they now adjust suitably.

After spending a couple more hours carefully shimming and checking wipe patterns, I think I have decided to split the difference between a centered wipe and a wipe on the pivot edge. The pros seem to be increased increased lift and decreased lash pad height. Cons appear to be increased valve train noise. Thanks for the input, I appreciate it. I did run into a curious problem that has me temporarily sidtetracked - Perhaps someone could share some advice: two of my rocker studs get very tight after being screwed more than halfway in. All the threads are clean and I have tried lube. After about 30 or 40 ft/lbs I got a little nervous about doing damage. I'm pretty sure the studs can take it, but is this common after having a head tanked or should I be worried?