70 to 73 was 240zs with 2.4 liter carbureted sohc 12v L24, only 2 seater available.

74 to 75 was 260z with 2.6 liter carbureted sohc 12v L26,and a 2+2 became available.

76 to 78 was 280z with 2.8 liter fuel injected sohc 12v L28e,2+2 available.

right?

when did a/c become available? power steering? I hear the 280s are more rigid because the frame rails go all the way to the back strut towers but added weight. what year did this start and how much weight did it add? How much does each year weigh? were there any other changes year to year that affect performance?

thank you for your help.

The info is close with some modifications.

"70 to 73 was 240zs with 2.4 liter carbureted sohc 12v L24, only 2 seater available."

This is true. 70 through 72 used SU carbs with only minor differences during the tree year run. This is the pure Zcar engine. Not as tourquey as some of the later ones, but it revs like crazy. It desperately needs a 5-speed tranny which was only available in Europe. 73 went to Hitachi carbs, very unsatisfactory, swap them out.

"74 to 75 was 260z with 2.6 liter carbureted sohc 12v L26,and a 2+2 became available."

The 260Z was a 74 only in the US. Same bore with more stroke. Same bad carbs. The engine didn't rev as easily as the earlier engine but there is nothing wrong with it.

The 74 260Z came in two body types. I'm not talking 2 seat and 4 seaters, I'm talking the early 240Z and the later 280Z body structures. The first half of 74 used the 73 240Z body and the last half of 74 used the 75 and later 280Z body. They look very similar except for the bumpers, but internally the later cars had more stiffeners and thicker metal. Much heavier. It is kind of like the difference between a 93 and a 94 Q. They look the same, sort of, but are very different on the inside.

"76 to 78 was 280z with 2.8 liter fuel injected sohc 12v L28e,2+2 available."

Make that 75 to 78.

"when did a/c become available?"

All years. Dealer added option from 70 to 74. The compressor was a York reciprocating unit and vibrated allot. Refit one of the later rotary types.

"Power steering?"

Not until the 79 or 80 280ZX. And it will NOT backfit. The only time you need it is with very wide tires.

"I hear the 280s are more rigid because the frame rails go all the way to the back strut towers but added weight. what year did this start and how much weight did it add?"

Alot more to it than that. No, the frame rails didn't go to the rear strut towers. Figure an early 240 will weigh 2250 and a late 280 will weigh 2800.

"Were there any other changes year to year that affect performance? "

Almost every part is interchangeable between 240s and 280s. Some body parts are different. Drive train parts from the 79 through 83 280ZX can be used to. My favorite drive train is the 83 NA engine, tranny, and a Subaru R160 limited slip rear in a 73 240Z or an early 74 260Z body. Still light weight, small bumpers still fit, and solid reliable 200hp with fuel injection.

Strangely enough, that is exactly the setup I have now.

Ive heard that the 280zx turbo block is sturdier and the bottom end is stouter. Ive also heard that the L series engine and the KA series engine are related in some ways. How do you tell between the early 260 and later 260? how hard to repair is rust on the floor panels?"No, the frame rails didn't go to the rear strut towers. Figure an early 240 will weigh 2250 and a late 280 will weigh 2800."so you're trying to say that whatever stiffness it added isn't worth the weight? what about non-colapsable steering colums? I hear these'll kill ya in a head-on. is the 70-73 L24 crank forged or cast?

No early Zcar is stiff by todays standards. Front and rear strut bars as well as a WELDED IN 4 point roll bar is required if you go much over 200hp in any 240 - 280Z.

Rust repair on any Zcar, even the simpler stuff like replacing floors, is generally more than the car is worth. Always go for the most rust free car you can find / afford. I buy parts cars all the time with hot engines, stiff suspensions, and expensive wheels and tires because the rusted out bodies broke.

The bottom end of any L series Z motor is unbreakable. You can't over-rev a stock motor because the valves float about 7300 rpm and the engine just won't go any higher. I ran 12 laps at Lime Rock with a busted oil pan, meaning NO OIL, and when the engine was taken down there was no wear on any bearings or the cylinder walls.

Don't worry about 240, 260, or 280 unless there is a specific look you want. All of the internals mix and match. For every day driving, I like the 77 - 78 280Z due to its bumpers. They are not pretty but they will take a hit. I had a MR2 slide into the back of my wife's 77 and the bumper took the hit with NO DAMAGE. The MR2 left on a hook with over $5200 in damage. That hit would have chewed the back of my 73 up.

In general, Zs are safe in most hits. The only bad ones I've seen have been driver door hits or roll overs where the roof came down.

Worry only about rust. Everything else is cheap.