We will try to keep this page updated on a regular basis. Articles represent solely the opinions of author and are intended for use by and enjoyment of the members of the Arizona Z Club. Although much of the information is intended as factual, its use is at the discretion of the reader who has the sole responsibility for any and all damage or resulting injury. Before beginning any project it is always important for anyone to seek the advise of professionals. The Arizona Z Club, its officers or members do not assume any responsiblity or liability for the use of the information contained in these articles. With that said enjoy yourself and enjoy the ride.
E-mail any comments or suggestions to Preston or Rosie at
prentpr@uswest.net
It is hot. It is summer. It is Arizona. They are hard on Z-Cars. So a number of us had a discussion about some of the best ways to keep our Z’s cool, thus keeping us cool and not stuck by the side of the road somewhere getting hot, both in temperament and physical discomfort. So how do you keep your Z-Car from suffering heat stroke? One of easiest ways is to keep your cooling system well maintained. What is well maintained you might ask? It is draining and refreshing your radiator once a year with a 50/50 mix of antifreeze and distilled water which removes the impurities. You should check or better yet replace your thermostat once a year. Some use a higher thermostat in winter and a cooler one in summer. Upper and lower radiator hoses and clamps should be inspected regularly. The fan clutch and water pump should also be inspected for abnormal wear.
So you know your car well and you have recently discussed the benefits of the above in several situations, including Memorial Day and Fourth of July picnics and parties. What you want to know is how you can make it run cooler. It is Arizona after all, one of the hottest places in America. Maybe you could use a radiator shroud or a four row high efficiency or aluminum radiator or add products like Red Line’s Water Wetter? These certainly work to help cool things down. Sometimes it is a simple adjustment of timing as a slightly advanced setting in the winter will not work well in the summer and cause overheating problems.
Everyone has their particular favorite cure, but one thing we found in racing is that if everything else is well maintained and working well that the simple inclusion of a restrictor plate in place of a thermostat and 3 ounces of Water Wetter with distilled water works wonders for keeping things cool. Restrictor plates are available at speed and performance shops. The best advise is too keep your cooling system well maintained. It is cheap insurance because heat can destroy an engine very quickly. Good luck and "keep cool".
This month I want to talk about Z steering. Does your Z feel kind of vague? Does it wander you as you drive down the road? Are you frequently startled when looking up from your map or Big Mac, to find yourself headed for the ditch, or worse, into oncoming traffic? You may have a steering problem!
Steering problems in the Z can be originate in many places. The first and most obvious, yet most often overlooked, is tire inflation. If you missed that tech article, go back and re-read it.
Alignment is another place that can cause steering problems. Simply aligning the car may not cure the problem, particularly if you have driven it that way for some time. If the tires have "worn funny'" they may cause a pull to one side that can only be overcome by replacing them. If they are that bad, you should be able to see the uneven tread wear with your naked eye.
A professional alignment will cost $40-50, and the mechanic will hopefully check for worn parts that may be contributing to the problem. Some of the parts that can cause problems include suspension pivot bushings, ball joints, and struts. Most of these are somewhat involved, but fortunately not common.
Additionally, there are several rubber bushings throughout the steering system that can wear to the point as to allow some 'slop' in the steering. This can lead to vagueness and wandering.
The most notorious of these are the steering rack bushings. The steering rack is the device that translates the rotary motion of the steering wheel shaft into linear 'left-right' motion of the tie rods that move the wheels. The rack is anchored to the frame of the car in front of, and toward the bottom of the engine. It is held to the frame by a couple of clamps and within these clamps you will find the rack bushings.
Why is this connection not metal-to-metal, you may ask? Quite simply, the bumps in the road are picked up by the steering and would be transmitted directly back to your mitts if you didn't have something to damp them out. Thus the bushings.
Usually made of rubber, these bushings will deteriorate from engine fluids, age, wear from vibration. As they get progressively worse, the rack is allowed to move left and right, sometimes as much as a half-inch. This translates into about twenty or thirty degrees of steering wheel rotation before anything happens at the front wheels.
As your car moves to one side, you turn the steering wheel the other way, but the car keeps going until the rack nuts the end of the play in the bushing. Then it steers in the direction you desire, and keeps going that way until your steering wheel input bottoms the rack in the other direction. Very unnerving!
Fortunately, this is a very easy fix. You can get the replacement bushings from the dealer or an import shop at a reasonable price. You can also get urethane bushings that are a little more stiff from many of the mail order Z places. The advantage of urethane is a bit more positive and precise steering, and supposedly a bit more life, though I can't personally attest to that.
Replacement of these bushings can be done with simple hand tools (preferably a socket wrench) in no more than a couple of hours.
Another, less commonly worn, but easily replaceable bushing is in the 'tension-compression' rods. It is difficult to describe where these are without photos, so get out your service manual (you do have one, don't you?), and look for them.
When getting the maximum performance from the Datsun Z car platform, no one pushed the limits further than Scarab Automobiles of San Jose, California. Using a trick learned from Carroll Shelby, Scarab slipped an American small-block V-8 engine into a light, foreign platform and created more than the sum of the two parts. Now something very different was under the hood of a Z car. It almost slipped right in, as if someone might have been thinking ahead.
The first Scarabs were used 240Z's. The cars had good, solid bodies but maybe tired engines. It is hard to believe a Z engine could ever get tired and die, but some did. The first mating of Z car and American small blocks used Chevy 327 cid V-8!s that were balanced and blueprinted. The result was a power plant rated at appropriately 260 horsepower and capable of 360 to 380 ft-lbs. of torque at around 35W to 3700 RPM.
Scarab did more than just install a small block, it highly modified the suspension and brakes to provide safety and good handling. Modifications included Koni adjustable strut shocks, heavier anti roll bars, Teflon bushings for the front struts and stiffer steering rack bushings. The optional, four-piston FIA front calipers were strongly recommended. Given the extra weight of the V-8, stiffer front springs were also necessary. The car rode on 205/70 tires in front and 195/70 in the rear. Larger front tires were used, again to compensate for some of the additional weight. How much more weight? Usually between 50 and 150 pounds depending on engine accessories, especially air conditioning. Power transfer to the rear wheels was handled by a Borg T-10 four speed with a Hurst shifter, although some Scarabs were fitted with automatics. Pirelli CN36s and P7s were usually the tire of choice.
When all this is combined the combination was almost as lethal as what Shelby produced. In fact, the Scarab was often referred to as the "Cobra of the Seventies". The car was capable of 0 to 60 m.p.h. in under six seconds and turning just shy of 13 seconds in the quarter mile.
Later Scarabs were fitted with engines which produced from 300 to 425 horsepower. Some had turbochargers. There was even a model that had over 600 horsepower, but this car had problems getting all of its power to the ground!
Despite the "negative press of rumors" and opinionated folklore, my research shows that the Scarabs were very well done and competent cars. At $30,000 a copy they had better have been! Installing the V8 did not require any cutting or bending, although some reinforcement was performed to the frame to handle the extra stress from the V-8. Cars were ordered with stock exteriors as "sleepers" or with cosmetic changes such as a front air dam, rear wing, louvered hood, flared wheel openings, all of the way up to the full blown Scarab body kit. Wheel upgrades were available, as were interior components like Recaro seats and leather trim. Factory Scarabs had special Scarab valve covers and Scarab "beetle" emblems in place of the Z emblems. While the "real", or factory, conversions were done by Scarab, do-it-yourself kits were also available.
If Carroll Shelby provided a do-it-yourself kit with all the relevant components would it have been any less a Cobra? This was definitely a super-car that missed its racing potential, born during an era of gasoline shortage scares and the lack of enthusiasm for super-cars, especially a Japanese-American hybrid.
It has been estimated that Scarab built about 250 cars, and supplied several thousand more conversion Kits. This hybrid provided its owner with reliability and neck-snapping V-8 performance born itself out of years of proven racing experience and passenger car use. Therefore, I consider myself lucky to have owned a Scarab along the way.
Editor's Note: The typical Scarab conversion placed the engine fairly far forward in the engine bay, primarily for clearance between the rear-located Chevy distributor and the Datsun hood latch receiver. Later conversions, like that described in the Jags That Run "Z V-8 Conversion Manual' placed the engine further back for a much better weight distribution. There was also a gain in oil pan/cross member clearance that allowed the engine to drop down a couple of inches in the engine bay. Done in this manner, your Datsun can have the punch of the V-8 without sacrificing its crisp handling.
I have worked on a couple of non-Z cars recently that had the same weird problem: semi-bad spark plug wires. Both were relatively new cars, and since a lot of us have older Zs, this might be the source of some hard-to diagnose engine problems for us.
First, a little Auto Mechanics 101. Spark plug wires are the little pieces of copper wire (or other conductive material) that transmit the 'juice' from the coil, where the juice is generated, to the spark plug, where the juice is used to ignite the charge (fuel-air mixture) inside the cylinder. At the plug, the juice is forced to jump a small gap from the center electrode, to the ground electrode. The electrons of which the juice is made, flow from the coil to the plug, across the gap and back to the coil. Therefore, they must have a return path to the coil in order for the whole scheme to work.
The conductive 'core' of the plug wire is surrounded by an insulating material (usually rubber, plastic, or something in between). The reason the core must be insulated is that the entire engine is a possible ground, or return path, for the juice. Without the insulation the juice would find it easier to jump to some other metal part from the core, than to go all the way across the plug gap and back.
On both of the cars I serviced, the engines had developed a bit of a rough idle and a 'stumble' when accelerating from a dead stop, or when shifting gears. A steady, rough idle is almost always due to one or more cylinders not firing properly intermittent 'missing' can be caused by other things).
One of the easiest ways to check this problem is to drive out away from the city lights at night, turn your car's lights off, and open your hood. You will be able to clearly see any serious 'grounding' as blue arcs from the plug wires to metal parts of the engine. If you see this, it is past time to replace your plug wires.
It is also possible to check the wires during the daytime, but it is a little more hazardous. To check the cylinders one at a time, pull each plug wire in succession while the engine is running. If the idle doesn't change, it is possible that cylinder is not putting out as much as the others, though problems other than plug wires can be at fault.
It is relatively safe to do this if you observe a few precautions. Use plug wire pliers which are insulated. Before you start the engine pull the wires one at a time-remember to grasp the boot at the end and not the wire itself lest you pull it out of the boot-and lube them with silicone spray, then reinstall lightly.
Replacing plug wires is easy if you get a set that is made for your car. In my experience the parts stores' generic wire sets don't work very well. A Z @s specialist or the dealer is about the best place to get a good wire set: Be prepared to pay $50 to $75 dollars. It is money well spent. Don't forget to put them on in the right order!
You can patch plug wires with electrical tape at the source of the grounding, as a temporary solution. It will take many wraps of the tape, however, because of the high voltages involved.
Tim Allen of the televsion program "Tool Time" , more often than not, can be heard saying that the solution to your tool problems is MORE POWERI!!! For a first, a second or even a third generation Z-Car that could translate into a radically built Z-engine, turbo, or supercharging. These solutions can end up costing as much or more than the car is worth and in Arizona could lead to chasing down costly overheating problems.
So what is a low cost solution or at least one within a reasonable budget. Why not consider a Chevy small block V-8?
To V-8 or not to V-8, that is the question... First it is important to consider your horsepower goals.
A stock-level Chevy small block puts out a range of 180 to 220 horsepower depending on the year and size of the motor. Others can easily put out 300 to 330 horsepower with little modifications to the cam, intake manifold, heads and headers. Still other modified small blocks can obtain 400, 500, 600 and beyond. Under 400, or between 300 and 375 is still easily within the 'OLE" pocketbook.
Typically Chevy displacements have been 262, 265, 283, 302, 305, 307, 327, and 350. The 400 is a different block with the same outside dimensions as the C.I.D. 350.
The stock 24OZ L24 engine is reported at 150 horsepower, so if you have a modest goal of 200 horsepower, then you can probably easily obtain it by a change of head and/or camshaft, adding headers, a exhaust system and modifying the carburetors. If you simply want to accelerate faster you could add a 390 or 411 gear ratio rear end gear, although your freeway driving will suffer since you will be revving your engine at a level well above normal when driving 55 m.p.h.
So there are easier ways to get 200 horsepower out of your Z engine without installing a V-8. However, Chevy small blocks do have more torque and you can certainly feel the difference between a 200 horsepower Z-motor and a 200 horsepower Chevy small block. A V-8 sounds "throaty' and pulls harder. With 300 to 330 horsepower on tap you have enough resident power to get yourself in trouble twice over what you have available in a stock L24 Z-engine.
So do you want to do it, huh, do you? Well, how do you get started. Fortunately, you have some people in the Z Club that have done it once or twice. You can draw on the experience of others. You can talk to others and get some very good tips, but be careful as some people are trying it for the first time and are making some very bad typical mistakes and are not even aware of it. The most typical is thinking that you don't need professional advice or parts; that it is simply a matter of jerking out the Z-engine and slapping in the "OLE" V-8 using the stock Z-mounting area. Unfortunately this puts too much weight on the front end and makes the steering heavy,, the car handles badly and brakes with a "lick and a promise."
The traditional Scarab V-8 mounting system mounted the engine too far forward and high, when it actually needs to be lower and back as close to the firewall as possible. Mounting it low and back helps maintain the original weight distribution of the car, or balance, so that the handling is crisp and the braking is adequate.
The next typical mistake is cooling. The answer is radiator, radiator and more radiator, as large capacity as possible to keep that "puppy" cool. The more horsepower, the greater the need for more cooling.
For professional V-8 @, I recommend Jim Cook Racing (714/8289122) and Motorsport Auto (714/639-2620) for their parts and their knowledgeable people. The V-8 conversion kits are available or you can buy individual pieces. Don't even attempt a conversion or even a conversation about a conversion without the manual from "Jaguars That Run" which specifically covers step by step their 24OZ conversion and parts. It will prevent you from making a lot of mistakes. This manual is available from John Washington at (602) 903-3625. John may also be able to help with your order as he sometimes orders from Jim Cook and Motorsport. Also, remember we can probably swing a Z Club discount if we coordinate on this activity.
For those of you that want to mount the engine too far forward, the old style Scarab mounting system is still available from Hooker Headers as well as headers for the Z car/ V-8 conversion. Some people are just traditionalists and want to do it the old way. These parts are OK for modest horsepower engines but tend to be too light for mega-horsepower applications.
Of course locally, you can contact me , Preston Pratt at (602) 9331652 as I have had or done about 10 conversions and that have had some or all of the mistakes, that had t be corrected. Maybe we could hold a tech session or a V-8 Conversion Clinic on this during a meeting or just "round table' and compare notes.
At the last meeting, I was asked to give a tech tip and sort of 'tipped my hand' by discussing one of my pet peeves that I intended to publish this month. The meeting turnout was land of light, so I will go ahead and print it here for the benefit of all of our members (and because Rick Hammond’s brother Steve said he would like to see the information in published form in order to settle a bet).
This month’s tip is about octane. A lot of people buy premium gasoline because it is 'better, when they have no idea how it is better or whether they really need it.
For retail purposes, gasoline is graded primarily based upon octane. The higher a fuel's resistance to 'detonation', or knocking, the higher the octane rating. The higher the octane, the higher the price.
Detonation is the explosive burning of the fuel/air mixture, or charge, in the cylinder. Many people think that is the way it is supposed to burn-not so. The charge should burn smoothly and evenly. If it does not, the result is detonation. You will know if your car is detonating because the engine will make a rattling sound under heavy load, like going up a hill at high throttle in the summer time. This is the result of all of the cylinders knocking in rapid succession, many times per second.
The piston and other parts of the engine exposed to the detonation can fail or have their life span @significantly reduced if it is allowed to continue. Under severe detonation, the engine can fail catastrophically in a matter of seconds.
Turbocharged engines and those that have been modified to increase the compression ratio (the degree to which the charge is squeezed by the piston), are particularly susceptible to detonation. High air temperatures can make it worse.
Let me digress a moment to discuss exactly what octane is. I am not a chemical engineer, so forgive minor technical errors, but here goes: gasoline is a product of the refinement of crude oil. Crude is 'cracked' in a distillation column. It is heated and portions of it boil off a@ different temperatures. These portions are captured, condensed (if they are to be sold as liquids), and stored separately.
The lighter, smaller molecules within the oil mixture come off first. Among these is a chemical called octane. These burn very smoothly, but because they are small, there is not much inherent chemical energy in them (because there aren’t as many chemical bonds, which are broken by burning, thus yielding heat energy). There is @ not a great quantity of them relative to the rest of the stuff in the crude mixture, so they are more expensive.
One of the last useable fractions of gasoline to come off the column is octane, which, if used alone knocks terribly. The octane number on the gas pump represents the knocking tendency of that particular batch of gasoline, compared to a mixture of octane and heptane. The ratio of the two components is the 'octane number'. For example, a '92' means the equivalent knock resistance of a mixture consisting of 92% @e and 8% heptane.
Forgive the digression, but the point of the discussion is that premium gasoline is expensive, and the reason for using it is to avert detonation and corresponding engine damage. If your engine is not knocking, i.e. non-turbocharged, and stock, you are probably wasting your money. In fact, since the higher octane fuels have shorter molecules, and therefore less energy content, you may actually decrease your fuel mileage by a small amount.
Yes, gasolines have all kinds of additives, many of them beneficial, but these additive packages usually vary by brand rather than by grade within a brand.
Should you find your car knocking on hot days, you can switch to a higher grade, but you might also want to consider retarding the timing on the ignition. I will save that topic for later!
This edition of Tech Tips is devoted to one of my Pet Peeves. This month it is tire pressure. I can't tell you how many times I have seen people over-inflate their tires. Usually this is because they don't know what the correct pressure is or how they can find it.
Interestingly enough, those same people sometimes let their car go for months at a time without checking the pressure. It is not uncommon to find tires on the same vehicle varying from 10 to 40 psi.
Part of the reason that people don't check their pressure is that today's tires seldom leak air. In addition, most drivers are not 'in tune' with their cars enough to notice a low tire, either by sight or driving feel.
The pressure that is listed on the sidewall is a If You read the fine print beside that number, that fact will be perfectly obvious. Correct pressure is a function of vehicle weight, and since all cars are different, there is no way for the tire manufacturer to print the correct number on the tire. The best they can do is tell you the most pressure that the tire can withstand.
The place to look for recommended tire pressure is either in the owner's manual or on a placard in the glove box or in the door jamb. Most Zs need about 28 psi. When you adjust to this correct pressure, you should have a quality (i.e. accurate) tire gauge. You can get a good one for $5 to $10. This is a very small price to pay for the potential savings you might realize. Today's radial tires are supposed to 'bulge' a little at the ground contact point, and it is difficult to tell how much. bulge is right (though a lot is definitely too much). Thus the gauge.
Tire pressure is one of the easiest parameters to adjust on the car, and it can have a dramatic influence on fuel economy, emissions, tire life, and handling.
I read a statistic once that said that for every pound of pressure that a tire is underinflated, the fuel economy declines by 2%! Emissions suffers too, since you have to burn more fuel to cover a given amount of ground.
In fact, if you are going in for an emissions test and think your car may be close, you can over-inflate your driving tires-the rears on a Z-to improve your results. Don't forget to adjust back to normal afterwards. Of course, if you car has any emissions problems, it is an indication that something is wrong and you should have it repaired.
If your tires are not properly inflated (either over or under) the car will handle poorly and the tires will protest under load (in turns). Over-inflated tires will tend to wear the tread out in the middle too soon, while under-inflated tires will wear out the sides.
Also, under-inflated tires experience excess hysteresis. This is flexing of the rubber in the sidewalls. Excess flexing builds up heat and too much will destroy a tire. Most 'sudden' blowouts
experienced while driving are due to long-under-inflated tires that have simply given up.
As a pilot, I have been trained to thoroughly inspect my aircraft before every flight. While I don't do this every time before I hop in my car for a short trip (neither do I floss every day), that training has taught me to pay attention to things that can be clearly seen or detected by driving feel.
Look at your tires to see what a properly inflated one looks like and glance at them occasionally as a check. Certainly, if your cars feels "funny" when driving, you should be paying enough attention to notice, and then find out why. And by all means, buy a good tire gauge and use it!
