240ZMan

The alt I used was from a 90 Maxima (Autolite #14661). The pulley did have to be swapped and since the connector is different, I had to create some short jumper wires with the appropriate spade connector crimped on each end. The main reason I chose the Maxima alt was that there was no grinding or cutting of brackets etc and the old alt could always be reinstalled later. Note: I'm assuming you have already made the wiring change required for an internally regulated alt. If you do go that route, here's how to connect the 2 jumpers: - The Field wire (green) is connected to the upper/outer connector when the alternator is viewed from the front looking up at it (from below the car). - The N (sense) wire (yellow) is connected to the lower/inner connector. I'm sorry I don't have any pictures as my camera was away being repaired while I did this project.

Actually, I have to disagree with that. On my 73 the ammeter measures current flow into or out of the battery. Under normal operations (engine running long enough to have replaced whatever current was used to start the car), the ammeter stays in the center (zero) position reflecting that there is no current flow to the battery. The alternator is supply everything required by the car. If you add an additional load to the battery, such as an e-fan, the current pulled by the fan will shown on the ammeter as "charging". The electrical system will think that the battery (actually the e-fan) is requiring the current to be recharged. Technically, as long as the total current doesn't exceed the max of the ammeter, you won't hurt anything, but under normal conditions your ammeter won't read zero either. Perhaps what you meant to say was to connect the high load items (using a relay of course) directly to the output of the alternator? That way you don't overload the stock wiring (easy to do) and yet the ammeter will still function properly.

Do you see the ammeter pulse with the changing load at idle, or when cruising (such as above 2k rpm)? If it's only at idle, upgrading to the ZX alt will help a little, but not a lot. At idle the alternator just isn't able to put out as much current as it can at higher rpms. You might want to make a list of all your planned electrical upgrades and how much current they draw. The total will give you a good idea if the ZX alt will meet your needs. Of course, keep in mind that electric windows aren't used continuously, but if you want to be safe, factor in your headlights on highbearm, the cabin fan on high, etc. In other words, use the worst case scenario. If you decide the ZX won't be adequate, there are several options, including a few discussed on this site. FWIW, when I converted to megasquirt I found that the ZX alt was at its limit when driving on a warm night with the cabin fan on, the e-fans running for the AC, high beams on, and all the load the FI system added, including the second fuel pump. I noticed that the alt was beginning to give off a slight smell - I think it was running at its limit. Swapping to a maxima 90 amp solved it. I didn't see any point in trying to fit a new alt into an old case - too much work and chance for error. An unexpected benefit was that at idle the new alt can put out more current. If I keep the idle at 800 rpm the lights just barely dim at stoplights. And my low beams are 80w

Ok, thanks for clearing that up. The only other thing I can imagine is that you have motor mounts that are too thick and have raised the front of the engine too much. But I've never heard of that, and given how far back the collector is, I'd guess the mounts would have to be at least an inch or two too thick - which doesn't seem very likely. I think you're back to needing a replacement header from MSA.

So are you saying that now that you have replaced the motor mounts, the old suspension that used to fit now hits the transmission support as well? If that's the case, then maybe it's not the MSA header that's at fault here. In my case, I didn't change the motor mounts and suspect they were (are) the originals. FWIW, I dealt with Sal, but I believe he left MSA a long time ago.

Wow, these pictures show the same issue I had 4 years ago when I started this thread! At the time MSA told me that the problem was with the jig used to align the header parts before welding and that it was later fixed. The second header they sent me did indeed solve the problem. But these pictures suggest they are having the exact same problems again. FYI, the pipe that connects to the header flange has a minor bend at about 18" to level it off. I can't remember if that's how it came, or if my muffler guy added it. But that won't solve the main issue that the collector is exiting at the wrong angle. Sorry to say this bajcsi, but I think you have to go back to MSA and have them send you a new header.

FWIW, it seems that some early Zs have the issues Arne mentions with rubbing in front. In my case (73 with stock valence) I have no issues. But I've seen enough who do with the same size wheels and tires to know that it's not an isolated issue. On the rears, after installing tokico springs and struts (illuminas) I eventually did cut the rear fenders. I had a very occasional rub in the rear with the 215/60-14 tires, and the 225/50-16 rubbed often enough after lowering that I had to do something. But like the front, it seems that others have run the same size and suspension without rubbing, so you probably won't know for sure until you try it on your car. Good luck! Edit: FYI, I'm now running Kumho MX tires which are a little wider than the ES100s were.

The zero offset street Panasports will clear either of the toyota 4x4 caliper upgrades (vented and unvented). You don't need the additional +6 offset if you're using one of those brake packages.

Myself and a few others have gone the reground cam route with good results. I used Delta Cams in the NW. The grind I chose was close to what Scheider calls their stage III. I was able to keep my stock springs and just change the lash pads. Total cost to regrind the cam, resurface the rockers, and shipping was about $125 IIRC. They even threw in a T-shirt. Idle is still reasonable, and it makes good power from 3k - 6500, pulls to 7k if you want. I've had mine in for 2 years now and once I had the proper lash pads and clearances, I was amazed at how quiet the valve train became. Even with the hood up it's barely audible. To Jon's point, I'm running an N42 head on an L28 with flat top pistons. I had to back the total advance off by about a few degrees to solve a detonation issue in the 4500-5000 rpm range. I'm at altitude FWIW (~6k feet) and run pump premium (91 octane). If I tracked the car more often, I'd go with new valve springs and more lift. But for a mostly street driven car, this combination has been excellent. BTW, I'm running with an 81-83 5 speed and 4.11. That combination fits the cam's power curve very well. As long as I'm willing to downshift, there's always a gear where the engine will be in its powerband. It's really a lot of fun to drive on the track or street.

I quickly glanced at it before I posted it and didn't see it either (figured I was just missing it), but I've used it quite a few times and it was accurate on my 73 so posted it anyway. The 72 had a rear defroster, didn't it? I can check my FSM later tonight.

Here's a pretty good copy of a 72. Hopefully the colors didn't change in 73. 72_240z_wiring.pdf

Something else to keep in mind with regard to CR, as you go to bigger cams with more overlap, the effect CR drops. All else being equal, which it never is , you could run with a slightly higher CR with a larger aftermarket cam vs. the stock cam.

I agree with Stephen that the N42 will be an excellent choice with webers. I ran that way for a while and was quite happy. BUT ... if you were to plan on doing some machine work ANYWAY, then I'd choose the P90 due to its better quench characteristics. I'm running an N42 on a L28 with flat top pistons and cannot run a full 35 degrees of advance without detonation. (I originally thought I was, but it turned out my damper shifted shortly after I reassembled the engine and I wasn't getting as much advance as I thought). From what I've read on hybridz, if you have to choose between CR and advance, you're better off reducing your CR to allow full advance than the reverse. If you are going to do work on the head anyway, then a P90 could allow you to have both a high CR and full advance. One last thought/question: has anyone done any dyno testing to determine how much extra HP is lost on an N42 with 10:1 CR when the timing is backed off due to detonation? I wonder if it's significant, or more just a bench racing issue.

Ozconnection, thanks for sharing the dyno sheet. From you description above, I'm guessing that the bottom curve was taken with the 2 barrel carb (not sure what that is - we didn't get any 2 barrel carbs here in the US) and stock exhaust, and the top is with the holley 4 barrel and upgraded exhaust. I see you gained about 35%, but when I convert to HP I see that you had ~ 80 whp before, and ~105 whp after. Many others have posted that a stock L28 (with twin SUs or FI) will put down ~120 whp. I'm not trying to "rain on your parade", but unless I've missed something, your original configuration had some serious issues and was not representative of a properly tuned stock engine.

A common problem with the SUs is that the throttle shafts wear out, begin to leak, and make tuning difficult if not impossible. Since new SUs aren't readily available, some have switched to 4 barrels (others to weber DGVs, etc). I've read of people who have properly set up small 4 barrels on Zs with good results. But they didn't achieve MORE power than with properly set up SUs.If your setup is working well, then go drive it and have fun! BTW, ZTherapy is a good source of rebuilt SUs that solve the leaking shaft problem.

I agree with Weasel73240Z. A larger carb will only increase power if the original was too small to provide enough air and/or fuel to the engine. In the case of our Zs, the stock SUs can provide more than enough air/fuel for a stock L6, and even for most modifications.

Disclaimer: I am oversimplifying the details of how the various components of an ignition system operate. To those who already are familiar with this, please "cut me some slack" - I don't want to write a term paper The job of the ignition system is to generate a spark at each plug at the correct time. To accomplish this, two things have to happen: #1) The distributor has to determine when to fire the coil that generates the spark #2) Energy must be applied to the coil at that moment. In the early Zs, mechanical points were installed in the distributor and they opened/closed every time another spark plug needed to receive a spark. The points were moved by 6 eccentric lobes on the distributor shaft. This both controlled the timing as well as applied the energy (voltage from the electrical system) to the coil. It was simple and reasonably reliable, but it was difficult to adjust and since the points were handling a large amount of current across an inductive load (the coil), the points would wear out. This resulted in cold start difficulties as well as poor spark at high revs. Electronic ignition systems still have to perform the 2 functions above. In the case of later 280Zs, the points were replaced with a sensor and magnets. The magnets are on the distributor shaft inside the distributor and rotate in front of the sensor. As they pass by it, the sensor generates a very small voltage. This accomplishes #1 above. The voltage is then sent to the ignition module which can be thought of as a simple amplifier or switch: it takes the small voltage from the sensor and then switches a larger voltage across the coil to make the spark. This accomplishes #2 above. The advantage is that there are no contacts (points) to wear out and the system is more stable at high revs. Note: the voltage generated by the magnets/sensor is far too weak to directly drive the coil. That's why a separate ignition module is required. For a mostly stock Z, the stock 280Z/ZX ignition system is quite adequate assuming it is in good condition. For those with an early points Z, there are various approaches to replacing the points: a) retrofit the later Z/ZX system (distributor and ignition module). This works well and can be done economically. use a self-contained after-market system. Pertronix is the best known example. It is a small module that is installed in place of the points. It performs both #1 and #2 above. Because of its small size it is limited in how much current it can safely handle, so it should only be used with the stock coil, or one that is just slightly more powerful (as measured by its resistance - with coils, "lower resistance" means "more powerful"). c) use a modular after-market system such as MSD or Crane. These devices only address #2 above (applying energy to the coil) and rely on something else to provide them the signal for #1 above. The advantage of the MSD and Crane is that they are physically larger so can handle greater loads and hence more powerful coils. They also have a temporary energy storage circuit so they provide additional energy to the coil beyond what the car's electrical system can provide on its own. MSD goes further and provides several sparks in a row to each plug for each signal from #1 above. The idea is to help with combustion at low revs. By about 3k rpm there is no longer enough time to generate multiple sparks and the system reverts to a single spark per trigger from #1. In practice, I found some small benefit with triple webers (always rich), but none when I switched to fuel injection. Keep in mind that the MSD/Crane box can be triggered by the stock points, a Pertonix device, the stock electronic distributor, or after-market distributors. A note on coils: a coil takes a low voltage (14V) source at several amps and converts it to a high voltage (10k+ volts) at several milliamps. More aggressive/powerful coils have a lower resistance on the low voltage side meaning they pull even more current than a stock coil, and are thus able to generate a more powerful spark. In practical terms, the stock points as well as Pertronix units cannot handle these low resistance coils. The main benefit of a more powerful coil is that you can run with a larger spark plug gap and still maintain a strong spark. For a non-racing engine this is of theoretical benefit, and my own informal testing did not show any observable benefits when I increased the gap. I'm not saying that some people won't find benefits on the street, but if you're looking for areas to improve the performance of your Z, this is one with very limited return. Having said all that, today I'm running with a stock 280ZX distributor with an MSD 6AL (the L means it has a rev limiter that kills spark above a preset rpm). If I were to build another car, I wouldn't bother with the MSD and instead would use the stock electronic ignition module, or the GM HEI modification (others have done excellent write ups on that so I won't cover it here.) I'd take the money saved and use it to buy better tires or brake pads

Hmmm, I haven't seen the 3% warning before. I can imagine a few reasons to be concerned, but none seem likely enough to put a big warning up.

Here's a spread sheet I built that lets you compare diameter and speedo error for a variety of tire sizes. The error is referenced to the early Z original tire at the top. If your model had a different size, just enter it there. When I had 14 x 7 rims I ran with that size (215/60-14). They fit without any rubbing and filled out the wheel wells nicely. But it's hard to find performance tires in that size now. Edit: the 195/60-14 size you are considering is 1.8" smaller than stock in diameter which equates to your speedo reading 7% high or roughly 5 mph too high at 70 mph. Tire sizes - 240z.zip

Do you really think your chances of surviving a wreck in a 30+ year old Z at 190 are better than at 200? You have no idea how naive you are. I'm going to make a suggestion that both of us may regret: spend some time on ogrish.com. I've only been there once and found it revolting. You'll see pictures of accidents that happened with safer cars at much slower speeds. They are horrific. But it is reality and I think you could use a dose right now. I really hope you can scale your expectations back to something safer and more achievable. /rant PS. Sorry for the lecture - I'm sure it's not what you want to hear - but I have a daughter close to your age and can't stop the "dad in me" from coming out.

If it is as described, it probably is worth it to someone who prefers 2+2s. But rust free on an early Z is unlikely.

I hope you didn't literally mean "street legal 200 MPH". The aerodynamics of the early Z is really poor, so the HP to get to 200 mph will result in an engine that is not streetable, and even if you do have that much power, the car won't be stable without a lot of aero mods. I'd suggest you shoot for a car that can hit 120+ at the end of the straight on a road course and you'll find you have a VERY ENTERTAINING car for the street. You can do that with the NA L6 without breaking the bank. But as others said, make sure you start with the suspension and brakes. With the stock 30 year old suspension, even 120 mph is going to be scary fast.

A word of caution: there's very little performance rubber available in 15" sizes for our Zs. A quick check at Tirerack for 215/60-15 summer tires shows only 3 choices: Pirelli P6000, Sumitomo HTR 200, and Yokohama ES100. That list is likely to get shorter, not longer, as each year there are less cars on the road using 15" performance tires. http://www.tirerack.com/tires/Compare1.jsp?width=215%2F&ratio=60&diameter=15&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&x=90&y=6&performance=EP&performance=MP&performance=UHP&performance=HP&performance=GT&RunFlat=All The cost of new wheels isn't that much greater for 16" rims, and there are a lot more performance choices in 225/50-16 sizes (4 pages worth at tirerack). If you go with 15" rims, I think it's likely that soon your only choices will be all-season tires.

FWIW, there's a person on ebay who regularly sells new vinyl seats (the entire cover) for Zs for a starting price of $140 for the set. I know that's not the same thing as buying a complete seat, but if my seats were in good condition except for the vinyl, I'd think that $250 was a bit high.

Going back to the original question about which carbs to choose for his L24, I'd suggest that the degree of modification to his engine will help make that decision for him. If the key engine breathing components (head, cam, exhaust) are stock, then it's likely that his max HP will be the same (or pretty darn close) with all 3 if they are properly tuned. If he has modified those components, then the problem with the SUs is that the only way to adjust the mixture at different RPM/Flows is to grind the needles. This is not a very easy process to master, and is clearly not reversable if you go to far (throw those needles out and start with the next pair). That is a significant benefit in my mind for the triple webers/mikunis on a modified L series engine - you can tune separately for idle, part throttle, and WOT. Of course, the jets are NOT cheap. I've not worked on 4 barrels on a Z so don't know how much/little tuning flexibility there is.