I know this is kind of a silly question but just out of curiousity...

What kind of fuel mileage should a '77 (still L28/N42) be getting, just any ballpark figures?

Figure about 20 for an average. Depending on how and where you drive you could get as low as 18 to a high of 25 or more.

Also depends on the condition of the mechanicals.

Thanks for your reply again 2many.

While on the subject of gas mileage i have never really gotten good miles per gallon in my 72. Probably about 18-20, is this just a fact of life with SU carbs or could there be a problem. If this is just the way it is i'm not worried about it i'd rather have performance. BTW i have ZTherepy carbs and an electronic ignition and new HGK plugs, power is good and the car seems to be fine. I just wondered if i were alone with this or is it just a 240 thing.

Depending on how you drive and if you spend a lot of time in stop and go traffic, 18-20 is probably pretty good. Do you spend a lot of time on the freeways at higher speeds? If you do look at the tach, it's probably on the high side of 2000rpm right? If you had an overdrive it would probably help a little.

It has been so long since I had a street car on the road and drove it regularly I was just guessing at the mileage. I'm not even sure I ever checked it when I did drive a Z on the road a lot. I just had too much fun driving it, and probably with the way I drove it, my gas mileage would have been a lot lower than yours.

Right it is on the high side of 2000 rpms gues that's got alot to do with it. O well guess it's time to get serious with a new trans.

You might want to look at the thread I put in the Tech articles on transmission and rear end gearing. You won't like your car in 5th gear if you don't swap to a lower ring and pinion. It will end up being too high and you'll be lugging the engine, same result, lousy gas mileage.

Thanks 2Many i did flip through your post, also i sought info on the big Z site about trans and rear ends. I like the 280z 5 speed with 3.90 rear end. Hey if i convert from the automatic to a manual do i have to change out the mustache bar with a later one. I talked to guy here in San Diego who ownes all Z Wrecking about how much it would run me for all the parts i needed to convert to a 5 speed. He thought about it and said 600. Good price for the parts i need?.

Well, if you are changing from an automatic to a manual you are going to need trans, clutch pedal assembly, and a few other little bits and pieces. $600 might be a little on the high side unless he's throwing in a 3.90 rear too. You only have to change the mustache bar and rear diff mount if you are going to use an R-200. You should be able to find a 3.90 R-180 out of a 200sx and use that, save changing parts, and save a little weight too.

I didn't realize you had an automatic. You already should have a 3.54 rear so to save a little money for the trans swap you might want to leave the 3.54 in until you get everything else done. Then you can search for the 3.90 rear.

BTW, if you can get your hands on the tranny, let me know, I am going to be stripping a 72 sometime this summer and can let you have the clutch pedal and all that for a lot less.

Thanks again 2Many the guy did qoute me a price for every part i would need, from pedals to rear end. I may take you up on your offer when you strip your car.

I have a 73 240 with the L 24 motor z therapy carbs, 1983 electronic ignition and a close ratio 5 speed and im getting 26 miles to the gallon, Im tickled pink !!!!