LeonV

No problem, glad I could help. Good luck with the resto!

You are correct about combustion temperatures being decreased but notice that I said nothing at all about thermodynamic efficiency. Instead, I mention fuel consumption/economy. This is essentially a reflection of overall engine efficiency, thus thermal efficiency is already factored in along with fuel conversion, mechanical efficiencies, etcetera. EGR reduces engine pumping work holding throttle and engine speed constant. Take the same engine, one with EGR and one without. The increase in intake pressure by the EGR charge reduces pumping losses and raises volumetric efficiency thus improving fuel economy and effectively total engine efficiency. There are other reasons that I can't recall right now, don't have my reference materials on hand.

Take a look at Sunrise Z in Glendale. I haven't been there but I've heard nothing but great things.

EGR is a win-win. For some reason people enjoy demonizing any device seen as "smog control." EGR decreases emissions and improves fuel consumption while decreasing NOx without detriment to performance. It is not a "desperate attempt by engineers" but rather an elegant and effective solution to a problem. Unlike a smog pump, EGR costs you nothing while improving fuel economy.

I put the 280Z tach in the other day and I finally have a properly functioning tach for the cost of $25.

Gotcha. I would use the stock manifold but the flange on my collector pipe is warped and finding a new/good one is pretty tough, thus the consideration for the header. Again, thanks for all the info!

Good to hear! I like the way your exhaust tucks into the valence, looks like a clean job. Are you using the stock manifold, and if so did you get a new collector pipe to hook up to the manifold or did you reuse the old one? I'm thinking of going with a system similar to ChrisZ's, with twin pipes hooked up to my Clifford header (or maybe stock manifold) utilizing 2 glasspacks per pipe. You only have 1 pack per pipe, so I may go with that if there isn't much highway drone and it's not too loud, except of course at higher throttle openings/engine speeds. Thanks for the feedback!

Cool, it's across the water from me, but I'll make sure to check them out when the time comes. I really appreciate the info!

I'm in the same boat, not wanting to take my 240Z to Maaco or do the 7-8k paint job since at that point I'd be afraid of chipping the paint. I'd love to hear a recommendation for a good SF Bay Area paint shop. Your Z looks great!

Nice! I'm planning to do the same, any driving videos? I keep thinking that the system will be too loud for me.

Search hybridz.org for step-by-step instructions on flare installation.

The ARB inherently has no effect in this situation, unless it is binding. The ARB contributes to a vehicle's roll stiffness. When one wheel moves relative to the other, then the ARB has an effect.

"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.