The Engine

It's a 2.4 liter straight-6 with an overhead cam and two valves per cylinder, fed with a pair of side draft carbs and a header exhaust. Nissan claimed 161 horsepower at 5600 rpm and 144 foot pounds of torque but it was probably less. Denver's mile-high thin air will reduce it further. I'll get it dyno'd to know for certain.

240z Engine Inside The previous owner said the engine had been rebuilt "fairly recently." A friend has a borescope camera so we poked it down thru the sparkplug holes to take a look.

The top photo shows two valves that appear clean without any carbon buildup. The crosshatched hone patterns on the cylinder walls were still visible. The bottom photo is a piston with the manufacturer's part number clearly showing.

The guy didn't lie.

These engines are pretty robust if rebuilt correctly and good for well over 100k miles, so it'll probably outlast me.

I bought a 2.8 turbo engine complete with everything except the turbo and the fuel injection's ECU. Eventually it'll get stripped down, then bored & stroked to 3.1 liters. I could rejuvinate the fuel injection, or use a modern aftermarket system, but at the moment the plan is normally aspirated carbs. It won't have as much horsepower as with a turbo, and it won't worked as efficiently as the fuel injection, but carbs are easier to install and the price is a lot lower.

Right now the focus is getting the car back on the road, so I'm keeping the stock 2.4 engine.

240z Engine My friends Mac and Adolpho volunteered to clean and paint the engine. Naturally I said yes. The block was soaked with a degreaser, then attacked with steel brushes, then soaked again and the scrubbing repeated. It worked pretty well.

Online I had found the "correct" factory shade of blue priced at $65 per can. I opted for a similar blue at just $8. With can in hand, Adolpho demonstrated the painting skills he learned while tagging in his youth. Mac stood back and drank beer and offered advice. We gave the valve cover a nice polish, then called it a day.

The final product is all bright and fresh and ready to go.

240z 5-Speed I did some searching and found a 5-speed transmission. It turned out to be an FS5C71B which is a "competition" gearbox with tighter gear ratios, a Porsche-type synchromesh, and rated for 250 ft/lb of torque. I replaced the front and rear seals, filled it with fluid, and I'm keeping my fingers crossed that it doesn't need to be rebuilt.

Just in case, I kept the orginal 4-speed.

240z Clutch While the engine was out, I replaced the clutch, which means the flywheel needs to be removed and resurfaced.

The 5-speed transmission came with the release bearing and the collar that attaches to the throw-out arm. My original transmission also came with a collar but it turns out the collars come in several different heights. Even though I used a stock replacement clutch I needed to measure how far it sticks into the bell housing in order to know which collar to use. The wrong collar means the clutch won't work. Click here to determine which one you need.

A lighter flywheel allows the engine to rev more quickly. Like with the collars, flywheels come in different weights, the heaviest of which is 23 pounds. Some people use flywheels as light as 10-11 pounds, which is great for racing can be difficult for street use. 16-17 is supposed to be a good compromise. If you want a lighter flywheel you have the option of letting a machine shop shave some of the metal off your existing flywheel, or you can buy an aluminum flywheel, but they're not cheap. I snuck mine into my local grocery store and used one of their produce scales to weigh it. Turns out it's 19.5 pounds, which is fine for me.

A final note: the genuine Nissan clutch is pretty robust. I know that because the clutch in my previous Z never failed despite a lot of abuse.

240z Header Heat Wrap The header got wrapped with heat tape. It's not difficult - it just requires some time and patience.

If you look online you can find a bit of disagreement on how it should be done. Some say you need to paint the header first, while others say never paint it. Some say you need to soak the tape in water before wrapping it. A few people claim heat tape is a waste of time and money.

Whether or not it increases performance, or keeps the engine bay cooler isn't really an issue because I like the way it looks. Unfortunately, once the intake manifold and carbs and air filter are installed, most of it won't be seen.

I also rebuilt the carbs (sorry, no photo) which is easy enough but afterward they need to be adjusted and synchronized. You can find synchronizers online and they're relatively inexpensive. It takes a little fiddling but essential for a good-running engine. As I mentioned at that top, I'm going to have the engine dyno'd and I'll let a professional do the synchonizing.

Back to the Build Details page