Mark Maras

@SoCalJim I'm sure Jai would appreciate the spring. I'll PM her address to you. Thanks.

@SoCalJim Thanks @Redwing

Datsun did add an elec. fuel pump to the 73 and 74 Zs to try and alleviate fuel percolation and vapor lock problems with limited success. Regardless of the number or type of pumps the fuel pressure at the carbs needs to be somewhere in the 3.5 - 4 p.s.i. range. More pressure than that will force fuel past the float valves (needle and seat) and over fill the float chamber.

@Patcon Are those the specs for the clutch or brake spring?

@Patcon Thanks for the info. I'm thinking the easiest way to replace the clutch spring is to source one from a good hardware store.

Jai (Redwing) found a spring in the drivers side foot well. Looking at the pic she sent it appears to be either the clutch or brake pedal return spring. My guess is clutch spring. A couple of questions. Are the clutch and brake springs interchangeable? I have a good brake spring and the nylon? spring perch from a late 71. Will the late 71 spring work on an early 76 280? Thanks.

How far down does the pedal go down on the first push? How far down on the second push?

@gnosez @Will S

Likewise. I've learned a great deal about Weber's from this thread. Thanks and keep up the good work.

The original problem may have been caused by an elec. pump "putting out a boat load of pressure" that was forcing fuel past the float valves. At this point in time I'd do a fuel pressure and fuel volume test as well as checking the float valves and the float height.

I seem to remember a part like that near the elec. fuel pump in the rear. I assumed back when I saw one it was a rock deflector of some sort.

An assumptions here. The engine doesn't cut out, it just runs out of power under load. I had a similar thing happen years ago. While driving my 240 down the freeway my speed dropped to 45 mph. Kicked in the clutch and revved it to 6 grand. Put it back into third accelerated at full throttle. It wouldn't go past 45 mph. Second gear, same thing. 45 mph was the limit. My Dad knew immediately what it was. Lack of fuel. Mine was corrected (temporarily) by blowing thru the firewall filter in reverse direction. Then a new fuel filter. Hope yours is that easy.

The fact that #1 looks good and others are carboned up makes me think the problem is electrical. Probably somewhere in the cap, rotor, plug wires, plug wire connections. New plugs, resistance check on the plug wires, double check the plug wire connections and a good quality cap and rotor should clear it up. Jalex in Panama had a problem similar to this. #4 plug was always a little darker than the rest. He had good NGK plug wires, at the time. He replaced the plugs, and bought a Bosch cap and rotor. His #4 gremlin disappeared with those changes.

IMO, the first thing to check is the accelerator pump in the Holley. With the engine off and the air filter removed look down into the carb. and operate the throttle linkage. There should be a visible squirt of fuel. I'd also verify the float level is correct.

The only info I had at the time (1973) was from the parts guy. I did a quick search and there are bakelite VW wire boots still available but I failed to find one with a resistor. I'd go with either of the ones from Summit. They both have resistors in them. You will have to unscrew the caps from the plugs to use these connectors. Hopefully your plugs have removable caps.

When I got my first Z, I swapped the plug wires to copper core wires. AM (71 Z) radio static was unbearable. My local parts supplier suggested using VW (I think) connectors that had a resister in them. They were a Bakelite (?) piece that replaced the rubber boot and connector that slips onto the plug. I cut the plug connection off the new plug wires, screwed the new connector on and voila no more static. I ran them for years with no noticeable change in performance.

@Ryans280z, @DamonR

As I recall, you're starting it on half choke now. You only need enough choke to keep it idling smooth. When it's idling you can blip the throttle to check the engine response. If the mixture is too lean (cold engine, not enough choke) the engine will stumble a bit before picking up revs.

Wow, Those are great numbers. Thanks for sharing.

I've used a lot of Permatex products over the years and had no problems. Either one will do the job but I'd use the 3M adhesive.

You'll be pleased to know that the slow wiper speed isn't an issue at higher mph. The wipers will lift off the windshield.

I've experienced a transmission whine and a prop shaft vibration. Fortunately at different times. The trans. whine was audible and sounded like a bearing going bad but didn't transmit any vibration to the shifter or the chassis. It was a bearing as suspected. The prop. shaft vibration in mine occurred above 80 mph and was horrendous. Sounded and felt like there was a 600 lb. bumble bee in the back. I replaced the u-joints but there was no change. Took the prop shaft to our local drive line shop to check the balance. They discovered a tiny dent in one side that screwed up the balance. They re-tubed and balanced it. No more problems. I'm not suggesting your tube is bent but it is possible to bend them. Check the u-joints first. Especially the front one.

Thanks Cap'n. I was hoping you'd respond. I had that nagging thought that it sounded too darned easy and logical. Anyone else want to chime in? @jalexquijano Ignore my last post to you. Leave the floats alone. (Everyone can breathe a sigh of relief) If you want to lean it out a bit (1/4 -1/2 turn) to see how it runs, try it. Most of learned by trial and error. Remember, your plugs looked nice and clean at the current settings and it runs good.

@jalexquijano A few more thoughts about adjusting your SUs. Make one adjustment at a time. It's fine to adjust both carbs at the same time but don't do anything else until you've driven it for a few days. If you really want to try adjusting the nozzles to 2 1/2 turns, consider this. One turn of the nozzle adjustment screw is 1 mm. Theoretically. if your nozzles are at 3 1/2 turns down you could raise them to 2 1/2 turns down and raise your floats 1 mm to compensate. Anyone out there have any thoughts on my theory? I'm still curious about that last compression test.

@jalexquijano If you're curious, go ahead and turn the nozzles up about a quarter turn. easy enough to do and undo. However, the previous compression test is still troubling. If the valves are too tight there could be an expensive repair bill in the near future. I would find the reason for the low compression first. Personally I think it was a botched test but maybe that's just wishful thinking on my part.