LeonV

"Maximum Brake Torque" It is a term for the highest torque value seen while varying spark timing, holding load and rpm steady.

Change that to .080" shave and .080" longer stems and that would be correct. Speaking of combustion chambers, a more efficient one will require less MBT timing so if you plan to go that route don't just advance as much as possible as you may pass MBT. Just FYI.

You can try a manual, a Haynes or the FSM perhaps. How did you tighten the critical fasteners without a torque wrench? I guess some people set everything to German torque spec and hope nothing comes loose.

Did you torque the suspension fasteners to spec with the car on the ground? Did you drive the car around afterward? It can take some time for the suspension to settle.

Precisely! Keeping the air out of your braking system is very important. This is a good lesson in keeping the brakes bled and when acquiring a used car, especially one that's approaching 40 years old, make sure to bleed the system. Previous owners tend to be terrible at basic maintenance, especially when you're like me and like to buy cheap Zs!

All the proportioning valve does is limit pressure to the rear brakes under high demand. At a certain brake pressure, the valve restricts pressure as shown in the FSM. That prevents the rears from locking up before the fronts which would cause an unstable condition (ever pulled the e-brake when driving on snow?). With that said, the proportioning valve is connected to the rear brake line, which is in no way connected to the fronts. In a nutshell, the circuits are isolated in the MC since the primary and secondary pistons operate their own circuits. The primary piston is the one which is actuated by the brake pedal. The secondary piston is actuated by the primary piston as it builds pressure between the two. You press the pedal, the primary piston traps fluid and pressurizes it's circuit while simultaneously moving the secondary piston and pressurizing its own circuit. If the primary circuit leaks, then the primary piston moves until it pushes against the secondary piston (no pressure builds between primary and secondary pistons), therefore actuating the front brakes in the Z. If the secondary circuit leaks then the primary piston pushes the secondary piston to its stop by hydraulic pressure (no pressure between the piston and end of master cylinder) and then pressurizes the primary circuit, the rear brakes in the Z. This book is very good if you're interested in studying the inner workings and all other aspects of brake systems. Bingo!

That is typical tandem master cylinder operation. Thus, you will have a dead spot in the pedal for a set amount of movement before the primary piston actuates its circuit. However, there should be ample stopping force with only half the circuit working especially if it's the front half. It doesn't have anything to do with the proportioning valve, which varies braking pressure to the rear cylinders in order to keep them from locking the rears first. In the bleeding example, the pedal will go to the floor if the fronts are not properly bled. If you have some time on your hands, re-bleed the rears with the fronts properly bled and you should have some pedal resistance. 5thhorsemann, when was the last time you bled your brakes?

Sure, that is a valid point. Some people's distributor vacuum advance curve doesn't match their engine. Three options here: switch the module for one with less advance, modify the current one for less advance, or go to a programmable advance which of course requires further modifications. It affects everything, although it does affect the mixture less as the butterfly goes wide-open. However you want to say it, the mixture nut does more than change the mixture at idle as the round-top carb only has that one circuit. You can't change the idle mixture without changing everything else. Try it out and get measurements of fuel economy before and after. Driveability in transitions and light throttle should also improve. I'm not trying to chastise anyone here, my L24 with triples has its vac advance currently disconnected as well. However, I don't plan to keep it that way. What's stopping me is getting the correct fitting that matches my vac advance hose and a broken advance module. I'm still rebuilding the suspension so it's not quite at the top of the list right now!

Strange. A rear wheel cylinder blew out and you lost all braking power? This is the reason for separate front and rear circuits so a failure in one does not cause a complete loss of stopping ability. Front brakes do most of the work so you should be able to stop just fine without any rear brakes. My old Z managed to stop without worry even with a complete loss of the rear brakes. I didn't even realize at the time that I had no rear brakes until I popped the hood and noticed no fluid in the rear brake reservoir! Methinks you have another problem besides the wheel cylinder.

Many people with triples don't use the vacuum advance for mainly two reasons. One reason is that individual runner manifolds will provide a noisier signal to the diaphragm especially with a high rpm cam. This can be somewhat alleviated with a balance tube or vacuum canister/damper. The other reason is that some manifolds don't provide a port for the vacuum advance thus the diaphragm has nowhere to get its signal from. Both reasons are not good enough to justify eliminating it. It has more to do with laziness and broken vac advance diaphragms. Vacuum advance is a good thing, though many don't take advantage of it.

Are you speaking of the big nut on the bottom? The big nut on the bottom affects the mixture across the entire band since you're changing the position of the jet with respect to the needle. It is not just an idle mixture adjustment even though the FSM does call it the "idle adjusting nut." You will see definite changes across the spectrum as you vary the mixture nut position. Testing shows this, using Steve's data:

Not quite. The round-top SUs have one circuit for all fuel delivery needs, the needle and jet. The needle and jet control everything; idle, transition, midrange, top end included. If you enrich the idle mixture, you then enrich all other modes. That is the inherent flaw in round-top SUs. These issues are what the flat-tops sought to eliminate, hence the flat-tops have a dedicated idle circuit and a power valve. Download the 73/74 FSM and check it out. OZ, I hope you understand what I'm getting at now.

I have extra round-tops that I can get rid of. I'm close to SF as well. Send me a PM if you're interested.

Bingo! You have just witnessed the inherent flaw in round top SUs.

Right. As I said, it'll work, but a return line is better.

I'm not sure what size hose I'm running, but it is slightly wider than the stock feeds to the SUs. As for the lines, I don't see why a return line would be bad and the Z is already set up for it anyway, and why remove the rail for that matter. I kept the fuel rail (and the mechanical pump as well) and am using the return on my triples. My suggestion: Tank > Filter > Mechanical pump > Rail > Hose into front carb > Connect carbs > Last carb feeds back into the rail > Return If you want to run a fuel pressure regulator, then place it after the carbs with a return line present and you now have better regulation and fuel flow since you are regulating the back-pressure and have a bypass for excess fuel. Only excess fuel goes past the regulator instead of the method you mention, which would put a restriction without a bypass and effectively heat the fuel before it even gets to the engine bay. Plus, with a dead-headed setup the fuel then has nowhere to go and further heat up compared to a return line and a back-pressure regulated system. Of course, I am not saying that your setup won't work and I'm sure many have used it and were okay with doing so. However I prefer the better option especially since the car already has the required provisions. If your Z is just a street cruiser then you probably won't have a problem with the way you were originally told.

Correct. I had a set of those in 15X7 that I sold last year. On the back it should say "OZ" and "Made in Italy."

You set the exhaust valve all the way open at TDC and your engine ran? That's the obvious reason behind the valve-to-piston contact. TDC is the overlap period of the intake opening and exhaust closing, and neither should be completely open at that point. Your cam timing is way off and you need to set it according to the cam card provided.

MSA twice pipes are 1.75" per pipe, and I think the old Clifford system is 2" pipes. BTW, can everyone lose the "back-pressure" idea already, it has nothing to do with improving pumping efficiency. You want your exhaust pipe big enough in order to not incur losses in the system. That's it. Before trying to justify the myth, please at least read this thread explaining exhaust dynamics. As for the OP's second question, a single 2.5" to 3" pipe is better than duals because of weight concerns, price and possibly loss of secondary scavenging effects if you plan on true dual pipes. I have a Clifford header and plan to use it to replicate the old dual system because I like the look and sound not because it is the best performer.

Or you can just tow with the front wheels on the ground. I'm not seeing what is wrong with that option. Why put in extra work when you can just lift up the rear instead of the front?

Same thing happened with my 240Z, still waiting for bodywork and paint. I ended up getting a 260Z to quell the pain, and I'm really trying to force myself to not go too deep! It feels good to refresh a car that's been neglected, a full resto is a bit more of putting long term gratification over the short term. Gotta stay committed!

"Never tow with the drive wheels on the ground." Just passing on advice from a tow truck driver that picked up my first Z.

I guess I'm just used to going all out! When I do something like brakes it usually ends up being a much bigger job... "say those bearings are pretty old", "should probably replace these nasty bushings too", "might as well paint the suspension while it's apart"...

Incorrect, the plates bolt to the strut.

An ARB does not nor should not affect ride height, unless it is binding somewhere which would not be good. The only time the ARB comes into play is when the ends are deflected, meaning it only applies a force when one wheel moves with respect to the other wheel. It should not be weight bearing.