Mark Maras

I'm probably over simplifying (or complicating) this but unless the physical distance between the cam gear and the crank gear changes, the slack in the chain remains the same. The slack will change temporarily while adjusting the cam timing unless the cam is rotated a bit.

I'd test the fuel pump for proper pressure and volume first.

When did the problem start? Before or after you worked on the pump and carbs?

You'll save time and end up with a better looking valve cover if you remove it first. If you leave it on you'll end up cleaning whatever polishing compound you use from adjacent parts. Besides, it's probably time to check your valve adjustments.

True. Back in the day we used offset keys to retard the cam timing and improve top end performance in drag racing engines. Years ago when replacing a timing belt on a Camry, I was sure I installed it correctly until I fired it up and drove it. Rushed job due to miserable weather and working outside. The cam timing ended up retarded by one tooth. The poor little 4 cylinder would struggle with low end performance BUT when it reached 4000 RPMs the power came on like gangbusters. It acted like the 12A in our RX7. It just wanted and loved more revs. I drove it for a few days until the weather improved and I could redo it. I was a bit disappointed after the repair. It was a lot of fun driving it with the cam retarded.

The jets should be 2 1/2 turns down, or so, at rest. I'd adjust the one that is all the way up down 2 1/2 turns and adjust the other one to the same depth which will probably be less than 2 1/2 turns down. They should run like that if the float levels are correct.

I've had better luck using good (not HF) channel lock pliers than vise grips to grip stubborn bolts, nuts, and studs.

Has the Z been sitting for a while? I'd start by pulling the caliper with the stuck piston and refresh (new o-ring) it first. Chances are the other caliper needs it too. Any possibility the calipers are on the wrong sides? The bleeder screws should be up not down.

@Robert9790 Portland, Or. Craig's List "1976 Datsun 280z - $7500". Post id 6973601510. Interesting Z. It's an injected automatic but if the body is good it's reasonably priced. I hope the sidewall ventiports (Buick's name for them as I recall) and other decorations on the fenders are just glued on. The wheels are A.R. Vectors.

Super glue on the hand grips?

My experience with a clogged filter was on I-5 doing 70 + mph when the car slowed to 45 mph. It would still rev normally with the clutch in but wouldn't go over 45 mph no matter what gear I was in. Thru the entire experience the engine sounded normal, no cotton ball sound.

When it lost power while driving would the engine still rev briskly with the clutch in?

What is insanity to some is job security for others.

Yeah, that could complicate things.

If you're talking about just the frame rails under the floor pans and not the ones in the engine bay it would be relatively easy to fab. your own. I bought my floor pan rails from ZedFindings and would do it again. Reasonably priced and excellent quality.

Don't disregard automatic Zs. Looking at Zs over the years I've found the automatic Zs are usually still in better shape, a better chance that they were garaged sometime in their life, usually were driven less spiritedly and don't cost quite as much. It's really easy to convert an automatic to a manual in Zs and the used parts aren't very expensive yet, especially if you go with a four speed. Carbed Zs ended with the 1974 260Z. Anything after that was injected.

Cliff beat me to it. What's missing in the description of the car is the most important item. Body condition, specifically RUST. Any visible rust is only 10% of what you'll find when it's opened up. The hood on this one appears to have rust bubbles on the nose of the hood. That's a particularly difficult spot to repair.

That's right. Out is down and rich, In is up and lean. We'll avoid the terms clockwise and anti-clockwise. Nice that you were able to clear it up with a 1/4 turn. In post #2 I wasn't sure if it was too rich or lean. I thought it was probably too rich (I assumed the plugs were a tan color) so my suggestion at that time was to lean it "Up a half turn".The choke test confirmed it wanted to run a bit richer. Congrats on getting it idling properly.

Thanks. If you notice a slight lag at the onset of acceleration (possible because you leaned it out a bit) you may want to try using 20 wt. oil. It will richen the mixture when you first hit the gas.

I'd try gently massaging? it back into shape. Thinking about it a bit more I'd probably try something similar to pulling a bow string. The hood being the bow. Perhaps clamps on the two corners with lines anchored below. Then a jack in the center to gently push up. The worst that can happen is finding out what doesn't work (failure is the road to success) and have to source another hood.

If the mixture screws are within 2 1/4 - 2 3/4 turns down it indicates the float levels are close if not spot on. Great news. Random question. What weight oil are you using in the carbs?

Plugs are looking good. I actually thought it might be running a bit rich. The SU chokes are a great way to check for a lean mixture. How many turns down are the mixture screws now?

The line is continuous but is much less defined where it passes over the rear wheel arch. Both sides were the same.

More info please. Stock cam? How well does it idle when the engine is cold with the choke on? Describe "perfect color" plugs or better yet, pics. Are the metering needles stock? My first guess is it's running rich at idle. That's assuming that as the humidity is rising, so is the temperature. If the plugs are a nice tan color like we used to try to attain in the good old days the mixture is likely rich. Plugs run nearly white with today's fuel. Assuming it's had a recent tune-up, including a valve adjustment, I'd put in a new set of BP6ES plugs, and lean the mixture adjustment nuts a half turn up and see if it improves.

I'm going to guess it's the brake master cylinder. Pull the rubber boot off the end of the master cylinder to see if there's brake fluid in the boot.