First I’ll deal with the 240 because that has the most problems. The first shortfall is a minor design flaw in the fuse block. This causes the 3rd fuse down on the right hand side to melt down. We can cure that problem and fix the fuse block as well, but it’s a two fold fix. We can do a minor modification to the fuse block itself, but if you install a plug ’n’ play relay kit to the dash and tail light circuit then you don’t need to modify the fuse block, only repair it as needed. This not only relieves all the pressure from the fuse block but it also saves wear and tear on the headlight switch because it no longer runs all the current through the switch.
The second electrical deficiency is the headlight system. There is approximately a 3 volt drop from the battery to the headlights, and all the power is run through the headlight and high beam switches. This shortens their life expectancy considerably. We now sell a headlight relay kit for the 240’s that is also a plug ’n’ play kit. This kit allows the switches to only be used for the triggering side of the system which is light duty and it no longer runs all the heavy draw current through them. This takes all the strain off of those switches as well as the fuse block. We also sell LED headlights.
Behind the fuse block and just to the right there are 2 inline fuse holders. They are accessed from the passenger side (for LH drive cars) right by the passengers left knee. They are used for the rear defroster and the heater fan. The holders are on a very short pigtail and it’s almost impossible to change the fuse in them. The fuse holders are also under rated for the 20 amp circuits that they are on. It’s only a 10 amp fuse holder and we’ve seen plenty of them melt down through the years. We sell a 35 amp rated fuse holder with a longer pigtail that needs to be spliced in to both of these circuits, thereby replacing both original fuse holders. With the longer pigtail they will be much easier to change fuses if needed. Of course you need to install the 20 amp fuses into the 35 amp rated holders.
Next is the alternator output, especially at idle. On the 70-74 cars the alternator output at idle is only 15 amps. On the 75-83 cars it’s only 20-25 amps. The stock alternators don’t start producing electricity until about 700-750 rpm. That’s fine if you never use any accessories, but turn on those accessories and it’s very common to have a discharge at idle. The common scenarios when you come to a stop are: Wipers slow down a lot, turn signal speed slows down, heater fan slows down, and your headlights dim. This is called a brown out effect and it’s bad for the car. Rev the engine up a little and these problems diminish. These problems are more noticeable on the 70-74 cars but brownout shows up on all of them. All of the 4 cylinder vehicles through the 60’s, 70’s, and early 80’s have the same exact problem.
Maximum output on all the z’s from 70-83 is either 50 or 60 amps, except some of the turbos were supposedly 70 amps. Most of the 4 cylinder vehicles up to 77 only used a 35 amp max output alternator which just isn’t enough power. Peak output on most factory alternators on these older cars is usually at 3500 rpm. The original alt for the 70-71 Z’s was also only 35 amps at peak.
This is exactly why we helped develop our high output alternators. We make one model for the roadsters, and another model for all of the 70-83 Z’s, one for the L20B, and Naps/z engine vehicles. These units are a direct bolt onto any of the aforementioned vehicles and don’t require any wiring modifications. If you have an externally regulated vehicle (used up thru 1977) all you have to do is unplug the regulator and remove it from the vehicle. No wiring mods to do there either.
Our HO alternators can produce 50 to 60 amps at idle, they kick in about 550 rpm, and reach peak output at about 2300 rpm which is over 1000 rpm sooner than the original alts. Peak output for our HO alts is 125 amps or 140 amps for our extra high output unit. These alternators cannot damage your existing stock wiring in any vehicle. They will only produce what is asked of them. If you add electrical devices to your car that it was not designed for they should ALWAYS have their own wiring and NEVER should the main circuitry of them be hooked up directly to your cars wiring system for power robbing devices. Only the triggering side should be connected to the stock wiring.
FYI, besides being hard on ECUs, switches, relays, power window motors, etc., the brown out effect that I mentioned before is extremely hard on fan motors and especially wiper motors. We can rebuild most wiper motors and bring them back up to full speed. The 74-78 Z’s need a headlight relay system installed as well but we haven’t developed a good quality kit yet. We’ve seen a couple of partial kits available on the market, but the quality control is way too low and we won’t put our name on it. We will be developing one of those kits, but we’re not sure when quite yet. The 79-83 ZX’s also need this same system upgrade. The 74-83 cars run all the current through the headlight and dimmer switch just like the 240 and besides having a 3 volt drop from battery to headlights, it shortens the switch’s life span drastically.
Last we recommend a backup ground system for the engine, also known as a redundant ground system. We will be adding that to our store in the near future.