I converted to electric fuel pump in my '71 Z and left the return fuel line in place. I figure this helps keep the fuel cooler because the heated fuel that doesn't get used in the carbs is returned to the tank which is cooler than the engine bay. I figure this allows more cool fuel from the tank to flow to the carbs. Also if it's available in Panama you should run ethanol free gas. The ethanol free I use is 88 octane and the car runs just fine. If you don't have ethanol free you should probably run premium. I do have ceramic coated headers and the heat shield under the carbs and I've seen my temp gauge get up to close to half way between the middle of the gauge and the hot side and didn't vapor lock. The weather here runs in the 90's (Fahrenheit) to 100 in the summer. As you've experienced, heavy traffic with lots of idling will heat these cars up!

6 hours ago, w3wilkes said:

I converted to electric fuel pump in my '71 Z and left the return fuel line in place. I figure this helps keep the fuel cooler because the heated fuel that doesn't get used in the carbs is returned to the tank which is cooler than the engine bay. I figure this allows more cool fuel from the tank to flow to the carbs. Also if it's available in Panama you should run ethanol free gas. The ethanol free I use is 88 octane and the car runs just fine. If you don't have ethanol free you should probably run premium. I do have ceramic coated headers and the heat shield under the carbs and I've seen my temp gauge get up to close to half way between the middle of the gauge and the hot side and didn't vapor lock. The weather here runs in the 90's (Fahrenheit) to 100 in the summer. As you've experienced, heavy traffic with lots of idling will heat these cars up!

Well in Panama we have 91 and 95 octane ethanol free gasoline. My car has the original manifold. I only have heatshield installed under the carbs. Maybe its time to consider ceramic coated headers. Thanks for your advice.

Faulty PCV valve? Not surprised. The quality control for these 'consumable' automotive parts is atrocious (spark plugs may be the only exception). They can cripple a car's performance, but spotting a defective item is difficult. You really need to install your 'tune-up' parts one at a time. If the car's performance collapses, you know you've just installed a new-but-defective part. Moral: Buy only the best -- even though they're just 'routine maintenance' parts. Even then, be alert and be suspicious. The auto business is a low-margin enterprise. Even name-brand 'replacement parts' manufacturers have to skate close to the edge in order to keep their shareholders happy. p.s. They do a much better job when it comes to supplying parts for new cars b/c now there are new-vehicle warranty costs involved and their customers (the auto manufacturer) will pay more to keep those costs under control. In the auto biz, it's all about $$$.

I will defer to others when it comes to your fuel pump circuitry. My thesis is all about making the system (your engine, along with its fuel and electrical systems) as simple as can be, so that problems much easier to diagnose. Once that's done, you can add back the complexity (emissions control equipment) as you see fit. If it were me, living in Panama and driving a carbureted 50-year-old classic, I'd limit that to the PCV system. All the rest of the 240Z's emissions control gear, viewed from a 2025 perspective, is -- not to put too fine point on it -- finicky crap.

Panama regulations does not require such emission stock gear. Its been removed. Still concerned i cannot make my engine rpm go over 6000 rpm at idle when fully warmed up and parked.

If the mechanical timing sprocket is on hole #3 it won't rev up very good at the top. I set mine on #3 after I rebuilt the motor with new parts. That advances the the explosion somewhat. I run full advance with the ZX distributor on my '72 240. I think it's 17 at idle and 34 degrees at 3,000 rpms.

But it won't go much over 6,200 rpms on the street.

Why are you reving it to max sitting still? That's completely nuts. No wonder you are constantly complaining.

NO OFFENSE INTENDED

It's your car, do what you want.

I told my #1 helper and the look on his face was pure disbelief. "WHAT?"

6 hours ago, siteunseen said:

If the mechanical timing sprocket is on hole #3 it won't rev up very good at the top. I set mine on #3 after I rebuilt the motor with new parts. That advances the the explosion somewhat. I run full advance with the ZX distributor on my '72 240. I think it's 17 at idle and 34 degrees at 3,000 rpms.

But it won't go much over 6,200 rpms on the street.

Why are you reving it to max sitting still? That's completely nuts. No wonder you are constantly complaining.

NO OFFENSE INTENDED

It's your car, do what you want.

I only rev it up after driving for 30 mins once parked.

20 hours ago, 72 Datsun 240z said:

I only rev it up after driving for 30 mins once parked.

You'd better correct or explain this. Otherwise, the CZCC members will write you off for good.

Specifically: No one (in their right mind) tries to rev their engine up to 6000 rpm at rest. Hot or cold.

What i meant is that i used to rev the car from 800 rpm to 8000 when i finished driving and parking the car back. I usually dont do it that often. Anyways i found a spare used pcv valve to replace the old one which according to mechanic was making plugs 4 and 3 foul due to oil. He capped this one and tuned the carbs so i could drive the car this way. I was wondering if i should keep testing the car this way? Or should i wait untila new pcv valve arrives.

Let's see, redline is 7,000 with the yellow zone starting at 6,500 RPM. Keep revving it to 8,000 RPM like you describe and your problem will eventually be solved when you have to replace the engine after it blows up! Oh, when that happens, you might want to select a different engine builder than whoever built this one. There is NO REASON for revving it like you describe, unless you have a death wish for the engine.