I am about to pick up a 71 240Z, and was wondering how everybody with origina engines in their Z's handle the lack of leaded gasoline? Do you add it to the mixture? Or just drive it regularly?

Do you use regular gas or super unleaded?

That thought just occurred to me as I was reading the 'how to build your L series engine" book.

I run 91 octane unleaded in my original 73 L24 with no problems.

Ditto, I run Super Unleaded...91 to 92 with no problems in my 1971 Z.

I use regular - 87-88 octane, no problems. Don't know if that will cause any issues, but it's been running fine.

These cars will burn the 87 - 92 octane unleaded with no problems, however if you want more performance, you can run AV-GAS that has the higher octane levels. Just do a search for AV-GAS or unleaded gas, and it will answer most to all of your questions.

Justin

I run 92 in my '71. Later cars have lower compression ratios and might be able to use less octane, but the '70-71s typically will ping on lesser grades (in my experience).

The original intake valve seats in a 240Z were bronze, so if the head has not been re-done with steel intake seats, there is the possibility of valve seat recession. I'd be concerned if you were going to drive it really hard, or a lot. But for a typical stock weekend driver, I wouldn't be too worried about it. Some day (if you keep it long enough and drive it enough miles) when it needs a valve job, have the seats replaced. Until then, just drive it.

These cars will burn the 87 - 92 octane unleaded with no problems, however if you want more performance, you can run AV-GAS that has the higher octane levels. Just do a search for AV-GAS or unleaded gas, and it will answer most to all of your questions.

Justin

Without going into a bunch of scientific mumbo jumbo, I'll just say that there are many reasons why avgas is not a good idea for a street engine. Especially one who's basic design is more than 40 years old.

sblake I agree with you. Av-gas. Its typically made to run in a much leaner environment, and while it works, its not ideal for your engine. Race gas with higher octane made for automotive use is the ticket for hot street setups.

While lead effectively raised the octane of gas, I think regular is fine. I run regular gas on my DD '70 and I've had no problems with it.

Hmm. My '71 pings noticeably on 89, even with the timing set to 5° BTDC. Might have to look into it a bit.

My '71 had a pretty good ping until I moved up to the high grade stuff. Test it out and you'll find the right level. Too much octane is not productive unless it is truly necessary.

I always run 87 in mine. Shell gas I've found makes it ping, so I've stayed away from it.