LeonV

Probably running hot, lots of carbon deposits in cylinder or your plugs are too hot. Couple of questions; what is the part number/heat range of your plugs, what temp thermostat are you running and has the cooling system been maintained and the coolant flushed recently?

Of course you should start a build thread, what are you waiting for!

Honda S600/S800, if you can find an example. I'd absolutely love to own one, although I'm not sure if I'd fit. Take a look at C10 Skylines, although that may be too close to the Z-car. They can be imported for less than you may think. How about a Soviet-era Trabant? They were small...

Regarding ignition advance, have you taken a timing light and checked at different rpm to make sure your advance is working? Otherwise, tape the fuel pressure gauge to the windshield and take it out for a drive. This is how I diagnosed my fuel delivery problem. At idle, I'd get 3-3.5psi but under load pressure dropped to zero or near zero. Before that, I was not sure if it was a fuel or spark problem either, but that sure helped pinpoint it. If fuel pressure checks out, I would hook up a timing light and put that inside the car while you drive so you can visually check if you lose spark.

Have you tried this yet?

If you floor it, will it hesitate then go, or will it completely bog and not pick back up? Did you check the float level? Drive around with a fuel pressure gauge taped to the windshield. Pressure can be okay at idle, but not with load.

As I said, the technique must be correct. Lots of penetrating oil, LOTS of heat and turning the nut a bit at a time. Some tapping from the other end and around the casting may help as well. I'm sure there will be some pins that still won't come out, but with patience most pins can be taken out in one piece. I'm not against the acme thread, it's just not going to be a magic solution. It'll probably just shift the failure mode from the threaded rod to the threads on the spindle pin. Patience, technique, and more patience will still very much be required.

The term "dieseling" means that the car continues to run, after the ignition has been shut off. I don't think that's what you're describing. If the engine is "lugging" then downshift, you're in the wrong gear for the given load. We need a better description of what is happening when you drive the car. What does it do at steady-state cruise (surging, bucking, etc.)? What does it do when you stomp on the pedal (buck, stall, etc.)? Also, do you have a heat shield installed between the exhaust and carbs?

The all-thread I snapped was hardened steel. No matter what kind of all-thread is used, the technique must be correct otherwise you'll be cursing another broken tool.

Something like that, I'll measure when I'm home. You are correct, the wall is thin where the M12 hole is tapped and that is exactly where failure occurred.

It may improve the tool, but that is a qualitative statement. I'm not sure how much of an improvement it will be, and if it's worth the costs. The failure mode of my all-thread was actually at the nut end, the all-thread simply snapped off! The bar itself failed, the threads were just fine. I was actually able to reuse that one after cleaning up the threads a bit. I applied a healthy amount of grease to the tool as well, before use. So, judging by my experience, the only way the acme thread would improve the design is if the threaded rod itself is inherently stronger than the standard all-thread. I don't think I noticed any twisting, that is what the grease is for.

I got a tool which utilizes the standard all-thread. I can say that it works well if you take it slow and add LOTS of heat to the strut casting. I broke my first all-thread from a combination of being too ambitious and slightly vague instructions. Turn the nut a little bit at a time and make sure the pin moves. Again, heat the strut casting like you're trying to melt the thing, I used MAPP gas. Of course, penetrating oil is a prerequisit for this job, but you already know that part!

I use a plain, inductive timing light, probably from Kragen or something. Some people prefer dial-back timing lights, but it doesn't make much of a difference. Use the plain-old NGK plugs, BP6ES.

If it's a plug meant for the L (e.g. NGK projected-tip plug), you'll be fine. With a compression ratio close to or at 10:1, you better be running pump gas, and even then there is a chance of detonation depending on timing. We can't tell you whether or not you'll get detonation without being there, nor can we tell you where to set initial timing without knowing what distributor you're using. A stock-headed L28 tends to make most use of the mixture with around 34-36 degrees of total timing, as demonstrated in dyno testing. The total timing depends on your initial timing plus the maximum centrifugal advance of your distributor. At your compression ratio, you may or may not need to back off on timing. There have been people that needed to go to 28BTDC to ward off knock, and there have been others that had no problems at 34BTDC, all with flat-tops and N42 head. FWIW, upping the compression ratio alone doesn't produce much of a change in torque, maybe a 1-2% gain, which likely won't be noticeable. Compression ratio is usually increased in order to keep cylinder pressures up when using a more aggressive cam. Without swapping cams (and matching intake/exhaust manifolds), the gain from a bump in compression is minimal.

If you look under the hood when it's dark, do you see arcing between plug wires that are close together? Some ignition system checking and maintenance will be necessary to determine the cause, not guessing.

It is straightforward: 1-2-3-4-5-6 from front of the engine, 1-5-3-6-2-4 counter-clockwise on distributor. I had a similar issue after adjusting my valves. Check your plug wires at the plugs (and distributor), they may be loose. I had to slightly crimp one of my plug wire ends so that it would "click" into the plug again. Also, be sure to check the coil-distributor wire. Also make sure that your distributor cap is seated correctly.

Great write-up! I plan to do this as funds allow on my early 260Z with triple Webers, and this should save me some time. Thanks!

If you want quiet and low drone, I would put a resonator in the transmission tunnel and something other than a straight-through muffler in the back. A chambered muffler would probably be your quietest choice, depending on construction of the chambers of course. Take a look on youtube for clips, many of them have a description of muffler used.

Excellent data, Phred! Philip, are you keeping in mind the differences between brake and wheel horsepower? Stupid question, just making sure.

Julio, This definitely sounds like something that can be repaired with paintless techniques. Vote #2 for paintless dent removal. I know I'd be very upset, especially with a Z as nice as yours, but luckily you should be able to get it removed without much fuss and financial outlay. Leon

BSFC would be at its minimum at max torque, not maximum. For those unfamiliar, think of it as the inverse of engine efficiency (proportional to torque), which is maximum at peak torque. As far as a good number, let me get back to you tomorrow, Blue, and I'll try to come up with something.

Wink-wink, nudge-nudge...

What??? I'm guessing you didn't search... It's not the seatbelt interlock. Seriously, all this takes is some research. I highly recommend following-up on my first post in this thread. Get the FSM from xenons30.com, it has a very good wiring diagram which I have used to solve many problems in my 260Z.

Welcome, Bob! Unfortunately I missed the Historics this year but I hope to see your Z in action sometime!

The alternator/VR are okay if you measure about 14.5V at 2500rpm or so. Sounds like a bad connection(s) somewhere. Check continuity at the fuses (not just visual inspection!) in the fuse box first to rule that out. Otherwise, trace wires and clean up connections. I always like to study the wiring diagram before getting to work and reference it while dealing with electrical issues. While slightly more complicated than the 240Z, the 260Z's electrical system is still relatively simple once you've studied it.