Rose's Ride

[Oddjob]

Rose’s Ride is a description of the project car which I am building for my wife. The car has previously been introduced in the New Members’ Forum, under the title New Z in Town. If you would like more detailed historical information, please refer to the earlier thread, which does include some pictures and a parts list.

Summary: The 1971 240Z was found on E-Bay in August '07. It was someone’s daily driver-type project car. The car was purchased and moved to the shop for the first phase of the work, which involved most of the chassis, suspension, drive train, brakes, and electrical. Some interior work was also done. It has just now come out of the shop after a year and a half, and is being driven on short shakedown trips.

There are still a few modifications left to be made in this phase of the work, and of course there are the inevitable bugs to be found and fixed. Once these remaining items are complete, the car will go in for bodywork and paint (phase 2).

Over the next few weeks, I will post some pictures, drawings, documentation and descriptions of the project so far.

[Oddjob]

Pictured is the Autometer gauge cluster which replaced the stock units. The gasoline gauge and a voltmeter have moved over to the A-pillar. Note the mileage on the new speedometer: 115. The half dash cap came with the car, one of only a handful of items which were kept.

[Oddjob]

The first shot is between the seats, looking rearward. The tail light panel has been replaced with a speaker baffle. The speakers are JBL GTO-937. The second shot is looking through the hatch at the cover over the spare tire well. The next shot shows the inside of the left side of the well. The right side will contain tools. The next shot is a detail showing the spreader bar, the harness attachment and the roll bar. The seats are another holdover from the previous owner. The tuner harness is new.

 

In several of the shots you can see parts of the floorpan finish. It has been stripped, coated with POR-15, covered with Boom Mat (a DynaMat clone), and then DynaPad. It will get carpet in Phase 3.

[Oddjob]

The basic engine was a stock L24, non-numbers matching, in the car when purchased. The engine tested too good to justify replacing it at this time. Eventually the car will get a warmed-up L28, when the present one dies a natural death. In the meantime, I concentrated on things which could be moved over to the eventual L28.

 

The carbs are early model SUs, polished, completely rebuilt and upgraded with MSA's improvements. The detail shows the velocity stack inside the K&N filters. The fuel rail consists of a Holley fuel pressure regulator, 40 micron filter assembly, Earl's distribution log and a Summit fuel pressure gauge. The manifold has been powder coated grey, and the heat shield chromed.

 

The battery is an Optima red-top. The grounding system can be seen to the left. I will give more details on this in a future post.

[Oddjob]

The engine was pulled during the phase 1 rebuild. It was stripped, and received a coat of blue POR15 engine paint. The aluminum oil pan from Arizona Z was added, along with a new high-output oil pump. All of the externally accessible seals and gaskets were replaced. All of the externally accessible bolts (rods, main caps) were checked for torque.

The water pump is new, along with the fan conversion kit to the newer plastic fan, and a set of aluminum pulleys. The harmonic balancer was replaced with a lightweight version. The alternator is the 105A internally regulated unit from Z Specialties.

The engine compartment itself was stripped and refinished with POR15 and a UV-proof gloss topcoat. The spreader bar had to be bent slightly in a hydraulic bender to clear the Nissan valve cover.

[Oddjob]

The early Zs had a reputation for overheating. Since this car is to be a daily driver in Florida, steps were taken to resolve this. In addition to the new water pump and fan conversion shown above, the radiator was replaced with the Arizona Z cross-flow aluminum unit. It should be noted that this unit is sized for the larger 280Z, but will bolt into the 240. However, it was found that mounting a fan shroud was not possible, at least not possible without far too much work.

The expansion tank mounts to the right shock tower.

The MSA oil cooler is also a key part of the cooling plan. It has been mounted on custom brackets.

The water tube at the rear of the engine was rusted out, and was replaced with a custom aluminum fabrication. It is powder coated grey. The stock part is no longer available.

The car has a 160° thermostat. It has been in the high 80s and low 90s since testing started here in Florida. The water temperature has not moved above 170°.

[Oddjob]

The ignition is an E12-80 “matchbox†distributor with a Flamethrower coil. The plug wires are NGK. The distributor was rebuilt as part of the engine refurbishment. Note the 10AWG (black) wire attached to the vacuum advance. This wire home runs to the ground buss.

The headers are MSA’s 6 into 1 with a ceramic coat.

[Oddjob]

The front brakes were already on the car, and are the usual Toyota S-12 four piston conversion with a slotted rotor. The paint and the braded steel lines were the only change as this appeared to be a recent addition.

 

However, the rear drum brakes were removed, and replaced by MSA’s complete disc brake conversion kit. They are expensive, maybe, but very convenient and relatively foolproof.

 

The master cylinder is a 79-81 ZX dual cylinder, mounted on a rebuilt master vacuum. You can just see the adjustable proportioning valve on the firewall below the throttle linkage.

[Oddjob]

Here are a couple of more views of the six-into-one header. It is ceramic coated, not chromed. The stainless flex coupling is a Vibrant 4556. Note that the collector, coupling, head pipe, muffler core and tailpipe are all 2.5" The muffler is a turbo muffler.

 

The car sounds very much like a small V-8 at idle and low speeds. It sounds more like what it is as the engine revs past 3500, but it still sounds good to my ears. It does not have any of that BLAATT!! quality you hear on the streets these days.

[Oddjob]

The car already had a later-years five-speed transmission conversion, which saved me the trouble. This is a must as far as I'm concerned. The transmission did get new seals and bearings, as well as a tight-pattern shift kit.

 

The stock flywheel was replaced with a 14 pound aluminum flywheel. The clutch is a Centerforce II. Both clutch cylinders were replaced, a stainless line added, and naturally, the throw-out and pilot bearings were replaced.

 

The driveshaft was replaced with an MSA aluminum shaft. Note that they only sell the longer shaft (later years, starting 1972), but since I was moving the rear end back 35mm anyway, I would have had to replace the driveshaft regardless.

 

The driveshaft loop is a Summit G-7900, which is a universal-fit piece, but it turned out to fit particularly well. Note the exhaust pipe is routed through as well.

[Oddjob]

The first thumbnail below is a reverse angle shot of the aluminum driveshaft, and shows the driveshaft loop in the distance. In this shot you can see the upper part of the loop.

 

The next shot was taken in the shop during the rebuild. Note the later years moustache bar.

 

The rear end is an R-180 which I chose to retain. Since the car will ultimately have a warmed-up L-28, and won't be raced, the R-180 is more than enough. The rear end got a complete rebuild, with 4.11 gears and a four-clutch limited slip unit. The LSD took 6 months to find (new). These are apparently becoming rare. Ultimately, Courtesy Nissan http://www.courtesyparts.com/ found me one, which shipped in from Japan.

 

The last shot shows the CV joint conversion which replaced the stock half-shafts and u-joints. If you are unfamiliar with this unit, I have attached a one-page PDF showing the details. The kit fit beautifully.

wcrcvhalfshaftaxlekit.pdf

[Oddjob]

The thumbnails below show various details of the suspension. The springs are Eibach, the struts/shocks are Tokico, the front sway bar is a 1" MSA, the rear a 7/8". All of the bushings have been replaced with urethane, and all of the usual suspects which are prone to wear have been replaced. Any component which appears grey in the photos has been powder coated. Anything black is POR-15 with the POR gloss topcoat.

 

The front and rear strut bars can be seen in photos above, as well as the roll bar. These components contribute to chassis stiffness.

[Oddjob]

Here are some odds and ends worth note...

 

The third brake light is an LED unit, a Hella 9071. If it saves a rearender on Rose's Z, it was worth the trouble.

 

The horns are also Hella. Loud, very loud.

 

The headlights are Hella 7" Euros, with 55/65 xenon bulbs.

 

This pretty much finishes a quick overview of Rose's Ride so far. I have not provided great detail on most of this, because it is all very well detailed in the Hybrid Z archives. Indeed, this is where I did most of the research for this build.

 

In my next series of posts, I will detail some areas which either aren't covered thoroughly in the archives, or for which I have gone a slightly different direction. I will also detail some of the inevitable problems we ran into, and their solutions. Some of this may be useful to others.

[Oddjob]

Rationale: When a motor vehicle is designed, a team of engineers is given two lists: one of features and another of constraints. These lists are themselves the product of various committees: marketing, finance, management, R&D, design. It is small wonder that the eventual vehicle is full of compromises, and sometimes downright mistakes. This process is probably necessary when you are planning to sell hundreds of thousands of cars and to try to make a profit in the bargain.

Unless you, the buyer, can afford one of those ultra-expensive, production-run-of-100 supercars, your starting place is going to be a mass market vehicle full of compromises. Fortunately, the design-by-committee process produces a real gem every so often, like the early Z cars. This is your starting place.

You are only building one car: yours. So you are not required to make any compromises at all, excepting those dictated by your own time, budget, and creativity.

The electrical system in the Z cars is a known weakness, and badly in need of upgrading. The electrical may have worked well enough in the cars when they were new, but it did not age well.

Most of the compromises you will want to address originally related to money. The copper in wire is expensive, so manufacturers use the fewest wires possible, and in the smallest possible gauges. Upgrading your wiring is relatively inexpensive when you are only building one car; it contributes substantially to the reliability and performance of the vehicle, and does not increase weight enough to make any real difference.

[Oddjob]

Theory: The Z as it comes from the factory uses a ground plane to supply the negative side of all its electrical circuits. This scheme is cheap to manufacture, both in time and materials, but does not perform particularly well, and really does not age well. The chassis is grounded to the negative side of the battery and alternator, and negative for all electrical devices is picked off of any convenient nearby metal. The trouble is, the ground plane is not a single massive piece of metal. It is composed of hundreds of welds, bolts and rivets holding various pieces of sheet metal together. To begin with, steel is not a great conductor as metals go. Add to this the necessity for undercoating, vibration deadening, adhesives, gaskets, caulk and other non-conductors, and things get complicated. Then add age: iron oxide (rust) is a semi-conductor under the best circumstances, and a non-conductor under the worst. With corrosion, road grime, paint, salt and oil working into once tight connections, and the ravages of 35+ years of vibration loosening everything up, you can see why your grounds might be less than perfect. I think I can state without fear of contradiction that the number one source of electrical problems in the Z is from bad grounds.

 

There are two general ways of improving your grounds. Both involve running a dedicated copper ground wire to each load device. Before you panic, no, you don’t really have to run two wires to everything on the car. You certainly could, but that would be more trouble than it was worth. The two grounding schemes are referred to as loop and star.

 

In looped grounding, you take a ground wire from your reference source, which will be either end of the negative battery cable. You run it from there to your first device, say the alternator case. You then extend from that point around to your next device, say the distributor. You keep going like that until you have connected every target device. Notice that I say “target” device as opposed to “every” device. You will certainly want to do this with mission-critical devices (the distributor), and possibly devices which are performing badly (that annoying tail light), but you need not do everything on the car.

 

In star grounding, you build a central grounding point (a ground buss) and homerun each ground from the load device directly to the buss. Again, you need not do everything on the car, just the important stuff. Of these two schemes, star grounding is preferred for technical reasons. There is a subcategory of star ground, usually called a technical ground, which is even a bit better. For those of you who are running ECUs, sensors and any other complex electronics, this is the way to go. A good technical ground scheme will usually clean up all sorts of electrical performance problems which don’t seem to make sense.

 

For my project, I chose a star grounding scheme. Since I deliberately selected a pre-smog, normally-aspirated engine without the need of an ECU, I did not need to go with a technical ground. The first thumbnail shows the ground buss mounted below the battery. This is a drilled solid copper bar purchased from Storm Copper over the internet: http://store.electrical-insulators-and-copper-ground-bars.com/index.html Click on “ground bars”. Note that it comes with stand-off insulators. I mounted mine on metal sleeves bolted directly through the sheet metal, without using the stand-off insulators. If you are going to do a technical ground because you have an ECU you must use the insulators to isolate your ground buss from the chassis.

 

The negative terminal of the battery is connected directly to the buss bar via a black 1/0 cable. The ground buss is then connected to the starter case using another black 1/0 cable with ring terminals on each end. Be sure to burnish (sand) the copper right under the terminals, and use lock washers (star washers are best). The remaining larger cables on the buss are all #4 AWG, purchased as part of a kit. You can see it here: http://www.sportcompactonly.com/Grounding-Wire-Kits/Ignition-Electronics/Performance/part_c-78_p-66401.htm This kit is pretty typical, and is actually intended for looped grounding installation, as the kit does not contain a ground buss device.

 

The #4 cables on the buss run to the alternator case, and the cylinder head near the spark plugs (2 places). The smaller cables, which vary in size from #8 to #12, run to the matchbox distributor, stereo power amplifier, horns, a distribution point for the headlights, electric fuel pump and a distribution point for the gauges and other under-dash loads. The third brake light is also grounded directly to the buss. When I get around to putting in LED tail lights, I will run a distribution point for that to the rear.

 

A word about wire size: bigger is better, within reason. I used a #4 to ground the alternator, but remember, it’s a 105A alternator. If you have a stock 40A alternator, a #8 would be plenty. A good guide is to look at what was there originally, if anything. If the design engineers used, say, a #14 to supply B+ to a light 12’ from the battery, you can bet they allowed the maximum voltage drop for that run. If you install a #12 (2 sizes bigger) for the B+ and a #12 ground for that same light, you should now get something very close to full voltage at that load. Just remember that Ohm’s Law applies; the resistance of the conductor material along with its length and cross-sectional size (gauge) will determine voltage drop to the load device. Well, that and contact resistance.

 

In simplest terms, the more connections you have in a wire run, the higher the resistance. This is one reason why star wiring is superior to loop wiring*. There are fewer connections. In a typical star-ground circuit, you will only have two contacts from the buss to the load. The number of connections and their quality will determine your contact resistance. These contacts should always be terminated: use the proper terminal, swage (mechanically compress) it, solder it, and heat shrink it. The heat shrink is not just an insulator. It keeps moisture and oxygen out of your connection, which are both sources of corrosion.

 

*For you ECU guys, the other reason is ground contamination, which is mostly electronic noise and ground loops, both of which upset electronics and can cause all sorts of undesired performance.

 

Another note: if you still have an external voltage regulator (I don’t), be sure to run a #10 wire to the ground point on the regulator.

 

Thumbnails 2-4 show the far end of various grounds.

[Oddjob]

As I noted above, one of the additions to Rose’s Ride was a Z Specialties 105 ampere alternator (thumbnail 1).

http://www.datsunstore.com/product_info.php/products_id/1?osCsid=3748af39a3ff513aec6edd48bedbde3f

Aside from the sheer additional capacity, it is a modern one-connection design, which is internally regulated. It bolts right in, and potentially cleans up some archaic technology and several potential failure points. As advertised, it was an easy installation, but it came with one very big gotcha.

After running the car about 100 miles after its rebuild, the indicated voltage on the car’s voltmeter dropped from 14.5 to 12.0. Some troubleshooting revealed that there was no output at the alternator terminal. Bad alternator, right? Nope.

From observation, I would have sworn, truly taken an oath that the alternator pulley was turning at the exact same speed as the engine pulley. It was not. The belt was slipping on the alternator pulley to such an extent that there was no output from the alternator.

The car has a lightweight single-groove harmonic balancer and MSA’s billet aluminum water pump pulley. These are both grooved for the stock belt (thumbnail 2). It turns out the stock belt slips badly through the alternator pulley, which comes grooved for a larger belt, which Z Specialties recommends (thumbnail 3).

By replacing the stock belt with a heavier-duty one of similar size to stock, but internally toothed, the slipping pulley was cured. However, turning on the lights produced the results in thumbnail 4. The new belt shredded in less than 30 seconds. I will explain why this occurred in the next post.

The balancer and water pump pulley were sent to the machine shop to be re-grooved for the bigger belt Z Specialties recommends (thumbnail 5). The long-term results are pending, but I think this will solve it.

The next post will go into some theory regarding why this condition occurred, and I will also discuss some design considerations which are not immediately obvious.

[Oddjob]

At some point, you have probably held an alternator in your hands. You probably will remember spinning the pulley by hand, which turned easily. It should, as its shaft is suspended on two good ball bearing assemblies. After you overcome the inertia of the heavy rotor, the shaft spins freely. This applies equally to a small 40A alternator or a big 105A one. If you mount the alternator and put the belt on it, but don’t connect any wires to it, your engine will turn it every bit as easily, albeit faster. At this point, the fan on the alternator pulley is the only significant mechanical resistance, and that is not very much.

Once you connect the wires and put a load (an electrical device which uses electricity) onto the alternator, it will begin to produce both voltage and current, which are collectively called electromotive force or EMF. The key thing you should understand here is that the alternator does not produce much of anything unless there is a connected load demanding it.

Now here is where it gets counter-intuitive. When a load causes the alternator to produce an EMF, that entire working circuit generates a reverse EMF in the alternator. In practical terms, what that means is that the alternator shaft gets harder to turn. This relationship is directly proportional. The more current you demand from the alternator, the more horsepower the alternator will demand from your engine to turn its shaft.

In my Rose’s Ride example above, the stock belt slipped because the big alternator became too hard to turn as the load on it increased. When the smooth stock belt was replaced with a toothed one, which wouldn’t slip, it worked fine until a bigger load came along (the headlights), then it broke.

But, you may say, why does the stock 40A alternator not cause the belt to fail? First, the small alternator is self-limiting. It can’t produce much more than 45A (surge), and therefore can’t demand much mechanical force from the engine. Secondly, when you load the small alternator at or above its capacity, you will get a voltage drop. You will have exceeded its ability to regulate its output to its preset maximum value. This is much like a brownout you may have experienced in a city during the summer. When the load on the city electrical grid exceeds its capacity, the voltage drops off. This voltage drop in your car will go from 14.5V to 12.0V, at which point your battery begins to discharge to support the alternator. The trouble is 12.0V is only 82% of your peak voltage and your performance suffers accordingly.* When you use a big alternator, it does not self-limit until 125A (surge). Nor does it go into voltage drop until over 100A. What that means is that the electrical system is performing at peak voltage pretty much all the time. The trade-off is that it takes more engine power to maintain this higher voltage.

For me, the trade-off is worth it. The matchbox distributor uses full supply voltage (there is no dropping resistor), so it will perform at its peak all the time. The lights will be fully as bright as they ought to be, the horn will be as loud is it should be. It is my belief that this trade-off literally makes as much horsepower as it costs, and is therefore worth it.

Since we are on the general subject, I am going to digress a bit, and tell you about some choices I did not make for Rose’s Ride, and why. In this case, I chose not to install an electric fan and an electric water pump. Before I go further, I will admit I think both are very cool, and both have their proper applications. But I think their application is not on an S30 with a NA L-series engine. Here’s why:

The usual reason given for this conversion is to “save horsepower†for the rear wheels. OK, good idea. The water pump and fan use a certain amount of mechanical energy to accomplish some work. That is, they circulate water and air, respectively, both of which are needed, and they are driven by your engine. If we assume that the amount of water and air circulated are the same for both the mechanical and the electric versions of each, then it follows that the amount of energy each uses must be the same, or very nearly so.

If you drive the pump/fan mechanically, it will take a certain amount of engine horsepower to do it. But if you drive them electrically, you will still use the same amount of horsepower or more to do the work. Why? Remember reverse EMF from the discussion above? The same amount of horsepower will be sucked up by your alternator to drive your electrical pump and fan. In fact, it will actually be more, because of conversion efficiency. Your mechanical water pump more-or-less directly converts rotational mechanical energy to moving water. But your electrical pump must get its energy from the alternator, which is converting the engine’s mechanical energy to electrical energy. The trouble is, it isn’t very good at it. The alternator is only about 40% efficient in making this conversion. So you really end up using more horsepower, not less, to drive these accessories.

Yes, you can adapt. You can use a smaller pump or fan. You can use a thermostat to turn the accessories off when they are not needed. You could even design a control circuit to use when you are racing. All of this is possible, but not, I think, practical for a daily driver.

* Note: The voltage drop condition described above is not the same thing as a low voltage condition when the car is idling. Low idle voltage is a problem with the design of the voltage regulator or the alternator itself. My 105A alternator produces a solid 14.5V at idle.

[Oddjob]

The big belt on the alternator works wonderfully. The car is actually running perceptably stronger.

 

I am going to leave the "Electrical" topic for a while, and come back to it. I am currently building the B+ (positive power supply) buss, and revising the associated wiring. When I have enough pictures, I will post.

 

The next topic will be fuel supply, which has some interesting problems, problems I notice others have experienced.

[Oddjob]

During the rebuild, the gas tank was removed, cleaned and remounted with new straps and a new sender. The vapor recovery was dismounted and cleaned and all of the hoses associated with it were replaced with new. The gas filler was repaired and chromed (it had some rust damage). The gas cap is new. The fuel lines were blown out with compressed air. The fuel pump is new, as are all the rubber hoses associated with the fuel lines. All clamps are new. The carburetors were rebuilt and the fuel rail was customized, including a new fuel filter.

When the car is under acceleration, it seems to “run out of gasâ€. It doesn’t do it in first, and sometimes not in second, but always does it in third and fourth. It does it sooner under hard acceleration, and later under moderate acceleration. At highway speeds, it will eventually do it in fifth while simply cruising fast. The fuel pressure gauge sometimes reads 0, sometimes 2.5 PSI (at idle). The gauge has been replaced once, as the first was thought to be defective.

Relief holes were drilled in the gas cap to eliminate any possibility of vacuum in the tank. This helped, but did not solve the problem fully. The ignition has been thoroughly checked, and is not at fault. The only real deviation from stock trim is that the fuel bypass line is currently capped off, as there is a pressure regulator on the fuel rail.

This problem has been described by others in the Hybrid Z archives, so it seems to be somewhat common. Since Datsun added an electric pump at the tank with the beginning of the 260Z model (retaining the mechanical pump), they were apparently also aware of this as a problem.

The existence of this problem stands to reason, as the inlet of the mechanical pump is 18†higher in the chassis than the opening of the siphon tube in the gas tank. It is well known that most fluid pumps do not “suck†well, although they will “push†fluid quite well. Most pumps prefer their inlets be gravity fed, so that they are flooded continuously. This is obviously impossible as the car was originally made.

From all of this I have concluded that installing an electric pump at the gas tank should solve the problem.

[Oddjob]

This is in response to an inquiry from PanzerAce:

 

The part is from MSA, and is listed as a "radiator overflow kit" on page 80 of their CD-ROM catalog, part #16-7000.