Racer X

Interesting. How long do we have to wait for part 2?

It seems you are having two separate, although somewhat related troubles. The vapor lock, which you say has been resolved. The cooling system isn’t performing well. So I have to ask, what is the age and condition of the cooling system? How long has it been since it was serviced? I don’t mean how many miles, but how many years? What do you have for a radiator, OEM style brass, or aftermarket aluminum? When was the system fully flushed and the coolant replaced? Is the thermostat performing as it should, and have you tested it to see if it is?

I believe the later 280Z door window frames had a channel that those fit into. It was supposed to address wind noise, and better seal the cabin from water intrusion.

A 72 up in Canuckistan. https://bringatrailer.com/listing/1972-datsun-240z-279/ Anyone we know?

On the early Z cars, the rods are compression rods, as they are behind the lower control arms, and the forces that act on them are compression forces. On the ‘79 and up Z cars, the rods are in front of the lower control arms, and are tension rods, because the forces acting on them are tension forces. Looks like the clutch hose needs replaced. Also note the twist on it. It has been installed poorly. When you replace it, be sure to not let it get twisted like that.

Welcome to the club, nice looking Z.

I was out in the shop today and remembered to have a look. The master cylinder sizes are 3/4” on the front circuit and 7/8” on the rear.

There are a number of engine remanufacturers. Jasper is one that comes to mind. I believe someof the Z specialists also offer remanufactured engines. This is sounding more and more like a very high mile engine that has not been properly maintained. I would bet that you will find excessive wear indicated by careful measurements. If it were mine, I would either go for a full rebuild, or an exchange reman. Also, the cylinder block deck looks to be in poor shape, and will require a cleanup pass at the machine shop to ensure the head gasket won't leak. Have you checked it for flatness? As I mentioned, machining stock pistons is not a good idea.

The method of getting the fuel/air mixture into the combustion chamber isn't relevant. What is important is that the quality, and the octane of the fuel/air mixture is correct for the application. If normally aspirated, a dished piston will only lower the compression ratio, and therefore the power output. If turbocharged, a dished piston would be more appropriate, as higher compression ratios don't work as well with forced induction. Milling the tops of pistons that aren't designed and manufactured to be machined isn't a good idea. Custom made forged pistons are available with the potential for machining valve reliefs included in the design. The dished pistons in this engine were used originally to lower compression and improve emissions at a time when manufacturers were under pressure to comply with the ever tightening emissions standards. Dished pistons were also used in the turbocharged L series engines used in the early 1980s Z cars.

Hot tanks don’t exist anymore, the solutions were hazardous waste. These days shops have a machine much like a dishwasher. Does the same thing, and is configured to filter the sludge and heavy metals to be removed for proper disposal. Even if Rebello or the race engine shop that refuses to entertain doing work for you don’t do what you are looking for, they should be able to recommend a shop that will. Also, you might consider a remanufactured exchange engine. Button your YouTube special back up, and order up a reman.

There is more to this than just compression. Bore, stroke, cylinder head prep, camshaft lobe profile . . . . You can't go wrong by sticking with the same setup the engine had to begin with. You're in California. There are a couple of knowledgeable and competent engine machine shops that are experienced with Datsun engines there. Rebello is the first that comes to mind. Also, the guys at Z Car Garage should be able to point you in the right direction.

How can any competent machinist say the crank needs ground, or the cylinders need bored, if he hasn’t actually inspected and measured them? A domed piston will net a higher compression ratio, not lower, requiring even higher octane fuel. Why not use pistons with the same top configuration as the original? Also, using EFI or carburetors won’t make any difference regarding compression ratio and fuel requirements. It will still be a fuel/air mixture entering the combustion chamber.

As mentioned, accurate measurement is paramount to deciding what needs to be done when reconditioning an engine. Disassembly, cleaning, and then measuring the cylinders, rods, pistons, crank, deck, bearing journals, cylinder head surface, valve guides, etc. I see some scoring in at least one cylinder, can you catch a fingernail in it? Also, the engine has a lot of carbon buildup on the pistons, and in other pictures there is evidence that this is a high mileage engine, and that it didn't see regular oil changes. Without actually doing the above, I cannot say what needs to be done, but it does look like the engine will require more than a ball hone on the cylinders and slap it back together. Find a good machinist who is familiar with the L series engine, and have a discussion about your expectations and budget, and what needs to be done.

For sure. The lines on a 240Z are tucked up inside the transmission tunnel, the lines on a 280Z are alongside the inside of the right frame rail. So changing to a 240Z floor and tunnel would require reconfiguration of the plumbing too. Again, unless the structures require replacement for corrosion, changing simply to use different floor covering seems pointless, as the covering materials could likely be done without changing the structures.

If I read this right, you aren’t replacing the floor pans because they are rusted away, but because you want 240Z floors in a 280Z? Replacing something that isn’t bad makes no sense. The only big difference between the 240Z and 280Z floors (and tunnel) is the bump out along the left side for the catalytic converter on the 280Z. So using 240Z carpet shouldn’t be an issue. You would also need to replace the carpet the 280Z has on the tunnel with the vinyl covering the 240Z uses.

Covid eh? That sucks. I thought we were pretty much past that unpleasantry. Get well soon.

Wilwood 2 piston calipers and 280ZX solid rotors in the rear (no parking brake), and a Tilton dual master cylinder pedal assembly with adjustable balance bar, and asymmetrical master cylinder sizes (sorry, I don’t recall the diameters, I’ll check when I get a chance).

Looks nice, you are doing some great work on this Z. I did this mod back before anyone made a “kit” for it. Sourced the Toyota 4x4 calipers and 300ZX rotors from the local parts supplier, made a drawing in CAD for the spacers and had a local machine shop cut a pair from 7075 T1 aluminum, picked the longer bolts at the local specialty bolt supplier. It was on my race Z, so I didn’t use the backing plates, instead custom building aluminum cooling ducts to direct air to the center of the rotors and also to the calipers. I made up my own stainless braided Teflon hoses with 37 degree JIC fittings and all the hard lines from stainless steel tubing. Works awesome, brakes that last all weekend at a race meet and don’t require bleeding after every track session.

To echo other commenters, grounds are often overlooked in cases like this, and also, the round slip on connectors at the sending units do get loose over time. Seeing as the gauges share a common ground, it would be the first place to look. Clean to bare shiny metal, and use dielectric grease when reinstalling to prevent further degradation over time.

A favorite of Golden Earring.

And now, car music.

I've seen Golden Earring 3 times , all great shows. I have every album they ever produced. Awesome band.

You might look at the rear brakes, the diff, and the half shaft u-joints.

Wish I lived closer, I’d take them. I forget how many sets I have. When I first got my race Z I picked up several sets, both 6”, and 7”. The class I ran in required 14” wheels. Hoosier still makes tires, the Street TD, a DOT legal bias ply with tread that works very well in 225/50-14. They fit well on a Z. And look just as good on the pavement as they do ten to twelve inches in the air.

Thanks for the props. I have a length of 3/4” heater hose I use, not only for carb setting, but to listen for exhaust leaks and other noises. Oh, and when tuning the carbs, I use a finger to lift the pistons.