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"New" 73 240Z question...and Hello

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New to the site and amazed actually because I never would have guessed that such a large community of Z lovers would exist on the internet.

Back in 1987 (I was 17 years old) I bought a '73 240Z for $1,000 from a guy in St. Louis. I had the Z for a couple of years and absolutely fell in love with that car. Unfortunately I made a mistake and got rid of the car.

Joined the military, got married, had kids....always miss that car.

I have told my wife a million times that I WILL own one again before I die.

Two days ago my wife told me that she found my birthday present (I told her I wanted a light bar for the front of my motorcycle because I am getting old and night driving gets worse every year) but didn't know if she was making a mistake so she wanted to show me the "present" on the internet.



'73 240Z

90% restored

103,000 miles



My son went and picked it up today.

I can't because I am stationed in Germany for the next 18 months.

So, I have 18 months to day dream, plan, shop....that woman cursed me I think.

So, the thread header said "question" didn't it?

My son told me the car requires "LEADED" gasoline.

I do not remember using "LEADED" gasoline in my previous 240Z.

I am confused.

So I guess the question is "Can unleaded be used in this engine for any length of time, and what modifications should I be planning and saving for?"

Any help will be much appreciated and again...HELLO!


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Welcome. I've always burned unleaded because that's all that's available. My understanding has always been that softer valve seats can be affected but this explanation from the EPA makes even that seem like it's not a problem. They even claim that 1971 was the last year that softer valve seats were used but I'm not sure if that applied to Nissan.


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I should be coming to the States in June for a week and will be able to drive her for the first time...gotta get all my registration stuff done NOW. I am in Germany, car is in Colorado, registering in Alaska...aaahhhh the military life.


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No, I have no idea what the 10% would be...I actually haven't seen the car in person yet.

I do know that the PO replaced the carbs with Webers and that the radio antenna isn't original. The stereo has been stolen and one of the air bezels on the dash is broken.

The interior pics I got don't look bad at all.

From what I remember with my last 240 the floor pans and rocker panels were an issue for rusting. I have no idea really with this car. I plan on owning it forever and restoring what needs to be restored so it really doesn't matter I guess...it needs what it needs and will get what it needs...I am just thrilled to actually have one again and one that is in pretty darned fine shape for what I know!!!

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Feel free to post the other pictures if you're not too concerned about the white glove treatment we tend apply around here. It's actually a good thing to have experienced eyes nit picking little details and will hopefully give you some ideas of where to start once you are able to start working on it.

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Long term, 100K+ miles - and the difference between running Leaded and Unleaded fuel may start to show up. When it does, it still won't be a significant difference in a normal street engine.

The lead additives in gasoline, in addition to being a cheap way to increase octane ratings, also had the side benefit of supplying additional lubricating to the valve stem/seal interface and the valve/valve seat interface. As lead was removed from the gasoline, the material composition of the valve stem seals, the valves and valve seats was also changed.. So the net effect in that area was minimal.

I think the article you referenced - intentionally used "relative" terms like "soft" and "hard" because in order to be specific - they would have to have used a very large matrix. A matrix outlining make/model/year produced as well as each model using different engines - then showing all manor of copper alloys and steel...

In general categories valve seats moved from copper alloy{other than tin}, to brass, to bronze, to steel, to hardened steel - as well as all of them with special alloy formulas between. The Bronze valve seats in the 71 were quite a bit harder than the ones used for years before that.. Ultimately of course the L28's started coming with steel.

Bottom line - you may want to use a higher octane rated unleaded fuel, as they contain additives to replace the lubricating functions that lead used to add.


Carl B.

Edited by Carl Beck
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Your car looks great, I also got my 260Z as a b-day present a couple of years ago and although is not restored the cas was purchased from the original owner! I am a new member here and I agree that this is a great community of Z owners, I've also read some great advice and tech tips as well. Z-ya

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