bunkhouse

Are you sure it's getting fuel? Running for a few minutes and then losing power or dying could be fuel starvation.

Any possibility of oil getting oil on the new clutch disc or pressure plate? I've seen old clutches shudder when they had oil on them.

If the noise goes away when the clutch pedal is pushed down, the noise is coming from the transmission. The disengaged clutch stops the transmission from spinning.

It looks like a CenterForce clutch.

When a stock oil bar is clean. solid and working correctly, the oil coming from the oiler holes lands on the cam lobes at idle.

Interesting. I hadn't heard of a V-12 Z at SEMA. Last year I sold a left door skin to a fellow who was using it on a V-10 Z for the SEMA show.

Prime it with zinc-rich primer.

I'd pull the valve cover and take a good look to see if there's any loose parts.

Is there any oil forward under the pinion seal?

Try asking over at classiczcars.com.

The folks over at Classic Z Car Club (czcc.com) are very knowledgeable on this subject.

I'd look into fuel starvation.

I'd start by checking ground connections.

What is the battery voltage when it's time to add the jump pack? I'd also check everything from the battery to the starter for heat (either a fingertip or infrared sensor) after trying to start it.

I've never seen a release bearing that wasn't smooth, not that it has to be if it fits properly into the diaphragm tangs. Seems like one might hear an occasional click when pressing on the clutch pedal as the bearing meshes with the diaphragm. I'd love to hear the theory behind this supposed improvement. Just had another thought. Is it possible it's supposed to stay meshed with the diaphragm and spin all the time? Which would mean reversing your adjustment.

There's a flat stop screw on the bottom that can be removed. It prevents the mixture screws (jets) from being removed.

Here's the simplest method for checking float levels I've found. The fuel level should be 3/8" below the carb bridge. Remove the carb domes and pistons. Turn the mixture screws and raise the jets to their top position. Now turn the mixture screws 9 1/2 - 10 turns down. (9 5/8 turns is 3/8") The fuel level should be close to the top of the jet. It doesn't have to be exact, close is good enough. Re-adjust the mixture screws to app. 2 1/2 - 3 turns down from their uppermost position.

I can confirm they're not US Indy wheels. Mine have the brand name on the inside. They could possibly be Anson Sprints.

I've used a smashed piece of copper pipe to back up small holes. I like the idea of a magnet to hold it in place.

I'd do a compression test to on all cylinders first. There shouldn't be water in any of the cylinders.

The noise sounds like a bad bearing to me.

The drop tests don't show any serious anomalies, IMO. A few more questions. Did it run well prior to the carb rebuild? Have you balanced the carbs? A better method for reading the plugs is to drive it until it starts to cut out, kick in the clutch, shut it off and then pull a couple of plugs before it idles. My gut feeling is the poor performance under load is caused by lack of fuel but judging by the air filter info it would seem to be the opposite, lack of air or too much fuel. You may want to run this problem by the folks at classiczcars.com. I'm Mark Maras over there.

It would seem that the air filters are at fault. If that's true they have to be affecting the carbs in some way. Engine off, lift both carb pistons to the top. There should be considerable resistance but it should feel even. No lumps or bumps. Now let them drop at the same time. They should both hit the bottom with an audible clunk at close to the same time. If the drop rate is substantially different, swap the pistons and test again. The other drop test, tests the rising rate. Remove the domes and pistons. Tape (masking) all the holes in the bottom of the pistons. Place the domes upside down resting in the tops of something like coffee cups. Place both pistons in the domes at the top (equal heights) and drop them at the same time. If the drop rates are substantially different, swap the pistons and test them again.

Pull a spark plug or two and report back about the color. Pics are better.

I believe is was called a differential counterweight. It's purpose was to lessen or eliminate the clunk when the front of the differential raises during acceleration.