lmcguffin

Colors can be changed, but automatic transmission....? That's a deal breaker....

Try disconnecting the wiper motor assembly in case something is wrong with the motor assembly that is loading the electrical circuit. The connector for the motor assembly is a round connector with a harness that goes thru the firewall close to the hood latch. There are 5 or 6 wires in the harness. Even though the wiper switch is off there is still power to the motor assembly as the wiper circuitry reverses polarity to the motor to "park" the wipers when the switch is in the off position. The ACC relay (if there is one) should be under the dash in the passenger footwell, above the fuseblock. Not sure about the fan (blower?) relay in the 76.

78 has electronic ignition, so distributor has pickup rather than points. If there is no spark, then check the connections at the electronic ignition module, which is located in the passenger footwell next to the fuseblock. There should be power at the module when the key is in the On position (Black/White=+12V; Black=12VNeg). If power is there then the module may be bad. With the engine cranking over there should be a small AC signal (<2V AC) on the Green/Red wires at the module from the distributor pickup. If signal and power is there with no spark, then either coil or module is likely bad. Check fuel pump by disconnecting the small wire on the starter motor solenoid (to prevent starter from operating) and then hold key switch in the start position. You should hear the fuel pump run while in start position.

It truly was great to get out and meet some folks, even if I was late. So much to learn and so little time.... Stephen, thanks again for getting this together. My wife even had a good time, even though I had to spend some quality (feigned interest) time in a jewelry store afterwards.... I have to give her credit though. This is her second episode with a Z restoration, so she's pretty much with the program. Looking forward to the next one. Lon

Oh my gawd, starbux and z-cars?? I must be dreaming... I'm located in Missouri City near US59 South and Hwy 6. I'll try to make it by. Too bad the engine for my 260 is on the stand right now--but it will be good to meet and gawk. Lon

My son is running a shaved P79 w/ flattop pistons in his 78 and has no problem with detonation on 91 oct. However, he says he can tell the difference when he gets back to TX and can get 93 oct. I don't recall how much the head was shaved but the resulting compression was around 9.8:1 (based on head cc results). He also has a stage II (274/.480) cam with stock springs and retainers. Stock EFI and headers. He made a respectable run at the public drag strip (beat a chevelle during trial) however suffered an offseated rocker. I attributed the rocker incident to excessive lash (he didn't check prior) and possible instability due to the valve lift with the stock springs, retainers, and maxed-out lash pads.

You also have to change the valve stem seals as well. There's a lot of threads related to this issue. Most spring sets for high-lift cams will require that the raised portion of the spring seat for the inner spring is machined flush with the outer spring seat, and then slightly recessed into the head. This is required to maintain the installed spring height for the particular spring load application. Stock retainers can handle up to .160 lash pad, after that you need special retainers. I've been doing a lot of research on this as I'm setting up an N42 head for use with the Nismo/Isky L-9 (490) cam. .460 is the recommended max lift on stock springs/seals; having said this, the Nismo catalog has an L-7 spec (270/.475) cam that doesn't appear to require special springs/retainers. Not sure what to think of this. The stage II MSA/Schenider cam is a 274/.480 spec. I presume that you have carbs in the 73 even though the N47 head was the fuel-injected, exhaust-liner head from the later 280s. It sounds like a lot of money to invest in what is generally seen as a lesser desirable head (not to start a riot or anything).

Here's a 78 with the EGR removed.

One thing I forgot to add to our list of woe is that the block was bored 1mm over. That meant I had to find 87mm flattop pistons, which are getting quite scarce. Soooo, I've got a new set of 87mm dish pistons; origin unknown..... for a good price.....

I believe that most reman engine distributors have the same disclaimer. Here's our reman engine story: My son found a 81-83 ZX w/ P79 long block reman on eBay listed for $400. It was from a distributor somewhere near Tyler, TX. He was hot to go the shaved P79/flattop piston setup. I told him not to go over $500 as it sounded too good to be true. He got ferverish and won it at $800, and then we ended up spending another $2000 to sort it out. Short list of issues: It was a P79 head, but a N42 block with dish pistons. Should have been F54 w/ flattop. Contacted distributor; he ended up agreeing to compensate us for half the cost of new pistons. I immediately spotted the shims under the cam towers. Time to go to the machine shop. Valve guides had been "resleeved". Yup. Had to tap out valves with hammer and drift. Installed new guides and did valve job. Straightened and leveled head. Main and rod bearings were improperly sized and too tight. Had to true up main bearing bores and machine crank to fit correct undersized bearings. Rehoned cylinders and matched to new flattop pistons. So after $1700 at the machine shop, and $300 for new pistons, and assembling the engine ourselves, we've got a good engine. Granted, the engine probably would have "run" as it was delivered. Not sure how long, but we wanted a good motor so we were willing to spend some money to get it right. Moral of the story: You get what you pay for. I think the average cost for a reputable stock rebuilt engine is $2200. Be careful unless you know the seller or can verify the goods. We only bought a long block as we had a donor engine for the remaining bolt-on stuff.

Thanks. We have to laugh at ourselves sometimes...keeps the balance. It is important to have a good-looking rear on a Z as that's what most folks see...

Actually, we are the monkeys. That is the 2-1/2" performance exhaust w/ Dynomax muffler as sold by MSA. The kit came with no instructions, and the muffler had no make or model info on it to be able to tell if it was the proper model. I did some research in the threads here and found at least one other person that had the same issue with fitting the muffler, and couldn't find anything in dynomax's website. Honestly, we just ran out of time and energy to devote to sorting it out. Put it on as best we could. It does sound good, even if it looks like monkey s**t.... Once the son gets out of college it will be his time and money to fix it. He's already eyeballing the SS coffee-can muffler that's currently fitted to my 260, which I don't really care for. Whatever I end up doing, it won't be what he's got on his now.

I bought a new dipstick tube a year or two ago, think it was one of the suppliers like MSA or Z Car Source of AZ. I was able to extract the breather tube by tapping back and forth with a rubber mallet and gradually pulling it out.

My son's 78. Holes were welded and indentations fiberglassed. Vintage Camaro-looking spoiler was his find... My 260 will not have a rear bumper either, however I have a less bodacious BRE spoiler for it. I haven't seen any manufactured roll pans, tho I did talk to a guy who had a sheet-metal shop fabricate one. According to him it was quite a process to get it made.

Lephosto, There are circuits that are fed from the fusible links under the hood that don't go thru the fuseblock. These are circuits for the fuel pump, fuel injection, alternator, etc. The relays for the fuel pump and fuel injection are located inside the bracket/box that the fusible links are mounted on. Check these devices for bad connections and/or current leakage. If the relay that supplies the fuel injection system is bad or has a welded contact then that could be a source of current leakage. Could also explain why the engine died suddenly.

Mike, I think your original assessment is the likely answer as it looks to be a current transformer. It's hard to tell, but there appears to be a connection to the small winding wire, which would generate a proportional current to the primary current flowing thru the heavier wire in the center. Probably used to detect current flow in the dome light circuit for an alarm system, etc. If it were a choke coil used to attenuate alternator noise for an audio device then it would be in series only without the seconday connection.

You're welcome. I replaced all the engine bay fusible links and relays in my son's 78 with modern fuse boxes and relay boxes that I gleaned from various Maximas at the junk yards, so I got to be quite intimate with all that circuitry. Check the mechanical side as well. I believe there is a filter screen between the gas tank and fuel pump or in the pump inlet. You said you had the car on jackstands; might have dislodged and sucked some trash into the pump suction which is causing it to starve.

The 78 has two relays in the fuel pump circuit; one is the smaller "fuel pump relay" and switches the 12V to the pump, and the other is the larger "fuel pump control relay". The fuel pump control relay is a unique device that has two coils with an interlock contact along with a form C contact (common/NC/NO). The relay from the parts house could be the fuel pump relay, which is a standard single pole normally-open relay. The fuel pump circuit has interlocks in the alternator (L terminal), oil pressure sending unit, and ignition relay. The alternator L terminal is basically an oil pressure buildup timer; once the engine is running and oil pressure is satisfied then the alternator is also operating so the L terminal is disconnected and the oil pressure switch along with ignition keeps the fuel pump running. If the alternator fails (ie: belt slips or breaks) the fuel pump will keep running as long as there is oil pressure. Lose oil pressure or ignition and the fuel pump stops. As you can see there are lots of places where a flaky connection can cause intermittant fuel pump operation. Here is something to try: Disconnect the small wire from the starter solenoid so that the starter will not operate. Have someone hold the ignition switch in the start position. The fuel pump will run. Try tapping on the relays and wiggling the connectors at the relays and the fuel pump to see if the pump will drop out. Then once the engine is running check the connection at the oil pressure sending unit. There are two wires there: One is for the oil pressure gauge (yellow/blk stripe) and the other is the oil pressure switch for the fuel pump (don't know the color). The oil pressure switch is common to ground at 0 psi and opens on increasing pressure, so if this circuit gets grounded then the fuel pump will drop out. So that could be a flaky oil pressure switch, an abraded wire, etc. There are also connections at the ignition relay that could be flaky as well. You really need the factory service manual to trace all this out. I would attach it but I bought it on cd and it's a protected file. I think you can download it tho from some other websites. Good luck.

Since you are checking voltage all this will tell you is that there is a load connected, ie: dome light. Reading 12VDC means there is a load; reading mV means no load or switched off. If there is load on a circuit that should be off then this could be a culprit. This was originally about checking leakage current (amps), but that requires you to be a little more familiar with your multimeter. You can check DC current with most multimeters, however they are limited to the amount of current they can read and will typically have a rating by the A or mA jacks (10A, 400mA, etc). There is an internal fuse that protects the meter (and your circuit being tested) from overcurrent. Checking current with your meter basically makes it a fused piece of wire, so if there's a direct short then something will blow, hopefully the fuse in the meter and not the meter itself. Be careful on the circuits where you read 12VDC across the fuse as there is a load there. Or get a DC clamp-on type as they are not connected to the circuit. Here's a link to a site that has some Factory Service Manuals: http://www.xenons30.com/reference.html See if you can get the Body Electrical section for your year (or close). This section will have the fuse box layout, fuse sizes, and circuit schematics/wiring diagrams.

If you have power at the fusible link but not at the fuses then the headlight switch is bad as it is located between the fusible link and fuses in the circuit. Bad design; all the headlight current is routed thru the switch. There are quite a few threads related to installing relays for the headlight, and I did so on the 78 280 that we restored (actually installed a relay box from a maxima to add relays for a/c, headlights, cooling fans, foglights, fuel pump, etc). My 74 260 project has the same burnt out headlight switch. Similar issue on the parking lights, however the parking light current tends to burn the molex connecter for the headlight switch as well.

Checking voltage across the fuse to check the fuse condition only works if there is a load on the fuse, ie: if the fuse feeds a switch that is open or off then there is no potential to create a voltage reading. The way to check a fuse without taking it out is to connect the negative or black lead to a chassis connection (preferable unpainted metal) and then use the positive lead to check both sides of the fuse. If the circuit is active then there will be voltage (12VDC) on at least one side of the fuse, and if the fuse is good then 12VDC on both sides. Also, the z cars have some circuits that are switched upstream of the fuses, ie: headlights. So the headlights have to be on to test the circuit. You can also remove the fuse and use the ohm scale on the meter (horseshoe or omega symbol). 0-1 ohms indicates a good fuse; open or > 100 ohms would be blown.

It may not matter with a stock cam, however we had a Schneider aftermarket cam and if we didn't get the cam lobe 180 deg from the rocker wipe pad then we would induce random small errors (+/- ~.002) in the lash setting. Just rotating the cam until the rockers had slack would not result in an accurate setup, and a noisy(er) valve train was the result. Also got best results doing the hot setup. I used a socket on the crank pulley with the plugs out (as Walter described) to get the cam in position. Yes, it beats your hands up, but ya gotta luv it . . .

Scott, Congrats and good luck on the restoration. My son and I recently did the same on a 78. Both he and the Z are away at college now. Took us around 18 months from the time it was parked till he drove it back. However I was working out of town for a good bit of that. Here's what we did: N47 block, bored .040 over, flattop pistons P79 head, shaved ~.030, cam towers shimmed and thicker lash pads Estimated CR is 9.5:1; shop CC'd the head but lost results :stupid: MSA Stage 2 cam, stock EFI/ECU, manifold, injectors, throttle, fuel system Removed EGR and disabled BCDD (check state laws) MSA 6 into 1 coated headers, MSA 2-1/2" exhaust/dynomax muffler Car has a nice idle rumble, slightly lopey, starts howling/pulling around 3k rpm. Spits and snarls when you let off the gas. Haven't dyno'd the car, so can't really even guess what the rear wheel HP is. My son told me he hit 90 in 3rd gear, then had up to 136 and got scared. The car prefers 93 octane, but doesn't ping on 91 oct. He can only get 91 oct where he is. Stock EFI works good; you can flog the car and then pull up to a light and it just idles perfectly. Starts right up, even in subfreezing weather. He wanted carbs but I wouldn't go there as long as the car is his daily driver while at school. Good luck on reigning in the boy as far as HP goes; seems that is what really matters to them, especially when GT-Rs are 400+ from the factory. You just can't get there w/ a mostly stock L28.

I had the same problem on our 78. Started rounding the square-head plug, so I went to Sears and bought an 8-point socket, 5/8" I think (mm not available). Used breaker bar and 6' cheater pipe, still could not get it loose due to limited movement space (pipe would hit firewall and bend). Since car was on jackstands I ended up positioning the breaker bar and shorter cheater pipe against the floor and let the car down, using car weight as force on breaker. Scary, but worked.