Gary in NJ

I'm sure he can overpay you too, for your troubles. Yeah, some people just suck.

When I use my leak-down tester I first set a reference pressure, i.e 80 psi. My tester holds this pressure within the gauge itself while I fill the cylinder. A very good cylinder will hold about 78 psi, about 98%. An acceptable cylinder will hold between 72 to 77 psi or 90% to 97%. So my leak-down tester has two gauges, a reference gauge and a cylinder gauge. When I'm done testing all of my cylinders I have a record for each cylinder that looks like this: #1 78/80 #2 76/80 #3 78/80 #4 77/80 #5 78/80 #6 72/80 The next time I run the test I can compare these figures with the current reading. The longer the history, the more validity to the test. This is the common practice in the aircraft industry which is where I have my mechanical training.

If a cylinder goes instantly to 0, then that cylinder can not support combustion. If the engine really has three dead cylinders, you'd know it. The engine would be rough running and more then likely smoking from the exhaust. Re-run the differential pressure test, but this time do it with the valve cover off the engine. This will allow you to confirm that both valves are closed; and if air is getting by the guide you can feel it at the source. I'm not sure what tool you are using for the leak-down test. I use an aviation style differential pressure tester. I believe the inexpensive lead-down testers accomplish the same thing. I usually use 80 psi for a leak-down test. Any cylinder that can hold 72 psi is a-ok. Below that I start to look for a source of the leak.

Hold on there, not so fast. I believe the bolts are stretch fit bolts and are intended to be (final) tightened once. The tightening sequence is to tighten all bolts to 32.5 ft-lbs and set final torque to 47 ft-lbs. The bolts are tightened from the center (cylinder 3) to the outer (1 & 6). If you have a loose bolt or bolts, then you may also be in need of a head gasket. Is your head gasket leaking?

Score!

Never happened....until we have photographic evidence.

I am not using "R" plugs on my 240Z, but I am using the NGK wires. I get ZERO noise in my Alpine AM/FM/CD/MP3 head unit.

It's either missing or has morphed into a fine-wire plug.

To do a proper reading, we would need to see into the plugs to see the insulator. With that said, if these were "high-mileage" plugs (5,000 or more miles) they look good from the outside. It's hard to determine mixture from high mileage plugs because is not unusual for them to be coated with carbon. They appear to be dry with no unusual wear patterns. Numbers 5 & 6 look a little better then the others. WHen you say the engine was hard to start after the replacement, could you describe what you mean and what other work was done along with the plug swap.

Why did you change your post? Got called out on your "Marketing" position with ZCCA? Yes, you fit the classic profile of a forum troll.

I'm with you Mitch. I'm not opposed to driving in the cold, but NJ coats the roads with so much salt and sand it takes a good month of rain to wash it all away. If it doesn't snow again this year (I haven't seen grass since Christmas), my car wont see public roads until March.

I digging your choke grommet avatar.

That 8C is just awesomeness.

1986 BMW 635CSi; one of the sexiest cars BMW ever produced. Post a photo of that too!

Welcome. Post some photos, past and present.

Opinions will vary on this subject. In my opinion, the SU carbs are far more reliable and easier to maintain then the primitive and somewhat finicky Bosch L-Jetronic fuel injection found on the 280Z. I've been on the hunt for a 280Z. When I find the right car, one of my first modifications will be to replace the FI with SU's. I can probably sell the FI system for the cost of freshly rebuilt SU's. Others will think I'm crazy, but I just ENJOY working on SU carbs. Sorting out FI problems is a PIA.

Yes, seal up that firewall. If you can't find the proper grommets, you can simply use RTV Black to create your own seal(s) for the electrical wires. You can't "roll your own" for things like the throttle linkage boot. Also, headers don't really add performance to a stock L24, but they do rust fast and they are louder. The OEM manifold is a good design and scavenges well. If you can find a good deal on an OEM manifold don't hesitate to pick it up.

That's gonna sound awesome. Post a sound clip when it's installed.

Depends whose doing the humming. Can I choose anyone from the boobs thread?

I did, in post #13. I don't see where I was bashing ANYONE. Up to this point all of the posts have been light and cordial; the only way to participate in this type of topic. In fact, I'd have to say that you are the first to bash anyone in this thread. Nice way to say hello noob.

Can I get an Amen?

If you do decide to replace the tach, keep in mind that Datsun used several different wiring schemes over the life of the S30. Know what you need before you buy.

You TYPED Hammer...I READ Hummer. A slightly different vehicle.

LMAO. The Speedo must read in kph. And you had to be going down hill, with a tailwind, on a Tuesday. But I do get your point that the thread is pointless.

Consider converting it to twin SU carbs. Easier to maintain and tune.