Gary in NJ

That's not how an engine is properly timed. You really need to get a timing light and set it correctly. The good news is that you discovered the root of the problem, now you need to resolve the problem.

The reason I asked the questions about loaded/unloaded conditions is that carburetors will behave differently under load then when lightly loaded. The fact that this doesn't effect the 5,000 rpm ceiling leads me to think that this is an ignition or engine timing issue. Do you own a timing light? It's time to take some measurements.

I have a couple questions on the 5,000rpm ceiling: 1) Is this ceiling in neutral and all gears? 2) Does it only happen under heavy load (acceleration or climbing a hill)? 3) What happens if you slowly apply throttle to WOT while in neutral? 4) What is the condition of the fuel filter? 5) What is the condition of the ignition system (points, condenser, cap, rotor, wires & plugs)?

LMAO. That's the quote of the day right there.

Good call Chris. By the time I started typing I forgot where the poster was from.

I don't think Casey is trying to be funny. The 240Z requires a deft touch on the throttle. It is unique and has been a source of complaints from many an owner. Back to the problem...These are 40 year old cars and it is entirely possible that a prior owner screwed something up. Give something a try... Disconnect the return spring on the the throttle lever and see if that has a significant effect on the break-out force. It's possible that you have an incorrect return spring. If that doesn't help, it would be worth the effort to disassemble the ENTIRE throttle linkage & interlock link on the carbs to determine if something is corroded or otherwise binding. Check the spring first 'cause its easy.

From the description it sounds like your car car has a vapor lock problem, i.e. the fuel in the fuel lines boils off from excessive heat and air gets trapped in the fuel line. This vapor lock is self clearing when the fuel line temperature returns to the normal range. The fuel return rail is supposed to keep this from happening, but in some cars it does happen. As a "quick fix" you can try insulating your fuel rail and return lines. If I were you I would also check that the return line isn't clogged or disconnected/modified. While this seems like the most likely resolution, don't rule-out a problem with the ignition system.

I don't know Mark, everything seems to be working real well. Are you new to 240Z's? I've never owned or have driven a 240Z that didn't have a high break-out force on the throttle. When they get gummed-up out or of tolerance the car is almost undrivable. When they are sorted out they are stiff but you can develop a feel for the correct touch in a day or two of driving. From what I see in your videos, your carbs are functioning well.

Didn't I just read a few days ago that there is a profile that is better suited for E10 fuel? Worth asking Bruce about.

Wow, the oil filter debate is only second to the oil debate. Every automotive/motorcycle/airplane/tractor forum I've ever belonged to in the past 20 years gets dragged through this one. When do we start discussing politics and religion

Back in my younger days I had louvers on my '71 240Z. But then again, back then I thought Walmart was a good place to buy auto accessories. If you car lives outside, louvers will: - keep the carpets from fading - make it harder for people to peek in - keep the interior cooler

You did well with the car. The rims alone are worth $800. How long has the car been inactive? You might want to read the many threads on how to start an engine and service a car that has been sitting. The limp clutch is from air in the hydraulic clutch system or a worn master or slave cylinder. Bleeding the system will go a long way in diagnosing this problem. Congratulations on a good find and welcome to Z club.

Mark, I had the same problem you describe in post 17. I cleaned (removed and polished the inside of the plastic and the ball with a Scotchbrite pad), lubed (white lithium grease) & adjusted the throttle rods. The rod from the bell-crank to torsion rod was on spec (7-3/16") but the rod from the pedal to the bell-crank was long. It was readjusted to spec at 4-1/4". This mostly cured the problem. Believe it or not, the final thing that made the on-throttle transition much smoother was a clutch adjustment. My clutch was engaging too high and when I lowered the engagement point the high break-out force of the throttle wasn't as noticeable.

Any good oil filter (Filter Fram PH8A, Purolator L30001, NAPA 1521) will work fine. For viscosity check the FSM (I'm not sure how cold it gets in TX). I drive my car 9-months and use 10W-40. I tend to use the "high mileage" formulas. FYI, Walmart will take back used oil.

No, but you will get a better view of the linkage. If the carbs were "messy", there is a good chance that the carb throat has a coating of carbon. Raise the suction piston so you can look inside (through) the venturi to the butterfly (it's really called a throttle valve). You might see a black coating in that area. A good cleaning with carb cleaner and a rag will get you moving smooth again. If the area in the throttle valve is coated, chances are the piston and chamber cover are coated too.

There is no direct link between the throttle linkage and the needle or the bell housing. These are Constant Velocity carbs. Changing the oil will have no effect on the break-out force of the throttle. Something is binding. Work the problem.

Every junction of that linkage should be sprayed with white lithium grease annually; starting at the pivot point on the accelerator right on down (up?) the line. Also, the FSM provides the proper length for each section of the linkage. If its never been checked it's worth measuring and adjusting. One wrong section can make for sticky/abrupt throttle operation. I also agree with Mr. Horsemann that a good cleaning will go a long way to reduce the high break-out force required to get your butterfly valves open.

It could be: 1) A poor or corroded connection at the battery, or 2) A bad cell in the battery Number 1 requires a little maintenance. Number 2 requires a new battery.

Happy Thanksgiving to all of those that enjoy their S30 cars. I will be further thankful if the snow that is falling stops before the road department starts spreading salt; because that will end my driving of my 240Z until the spring.

I have to admit Sarah, that was new to me as well. To my ear, the sound is the uncontained exhaust partially bypassing the manifold. If you ever heard even a small engine like a 125cc dirtbike without a pipe you could understand how painfully loud the exhaust can be.

Doesn't sound logical to me The bad gasket doesn't get drawn into the combustion chamber. A bad exhaust gasket "sounds" like tapping. The backfiring is caused by air being drawn into the exhaust. To confirm a bad gasket look for "splooge" (dark oil) around the exhaust manifold. You can also see the effects of a bad gasket by putting the car in a dark garage; if it's real bad you'll actually see flames (very slight) coming from the head. While an exhaust gasket is a simple repair, the age of the car almost guarantees a frozen nut or stud.

It's hard to diagnose a noise from typed words, but that wont stop us from trying First off, I doubt the valves are hitting the piston. That usually only happens once, and then the engine stops working. An exhaust gasket would be my first guess, followed by a head gasket. It could be a bad/worn main bearing. That noise usually presents itself under light load at mid-rpms. If you have access to a stethoscope you can listen to the engine in various places through the valve cover and the head itself.

Sarah, I know exactly where you are going here. Without talking to the design team first hand we can never know the true influence(s) on the S30 design. However, with that said the S30 stands proud when compared to cars like the Ferrari 250GTO, Jaguar E-Type, Maserati Mistral, Lotus Elan, Lamborghini Islero, Chevy Corvette and yes - even the Toyota 2000GT. All of the aforementioned cars share a similar design style - even if not one of these cars influenced any other car on the planet. Cars of that era share the same design language, i.e. a proper (for a sports GT) "long snout" look. That in and of itself should not kick-up a hornets nest. I hope we could all agree on that.

Got in my 240 and drove 25 miles to the nearest Ethanol-Free gas station (they even had a big sign out front proclaiming the fact), rolled up to the pump, only to find that the station is closed on Sunday. Damnit!

Is that the Red Bank area? If so that's a good 70 miles from me so I can't commit. But I'll be driving my 240 at some point tomorrow, so you never know.