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Thread: Engine differences about Series 1 S30 Zs?

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    Default Engine differences about Series 1 S30 Zs?

    I apologize if I have asked this question here before (so I won't get fried again by certain "contributors" to the forum).

    Could someone describe the physical differences between the L20 engine and the L20A engines from 1960-1972?

    Apparently the S30 Z with the L20 was only available in the Japanese Home Market cars?

    I do know both are 6-cylinder engines and that the L20 is a 2.0 liter engine and that's about it as far as what I have learned thus far.

    What I did find in Wikipedia is:

    "L20/L20A
    Nissan L20 engine

    The L20 is a SOHC 12-valve engine produced from 1966. A 78.0 mm bore and 69.7 mm stroke meant a displacement of 1,998 cc. Later, this engine became the L20A to avoid confusion with the four-cylinder L20B introduced in 1975. The L20 was used in the Nissan Skyline 2000 GT and Nissan Cedric 130, producing 109 hp (81 kW) for the 2000 GT and 123 hp (92 kW) for the Cedric."

    This does not indicate the L20 was used in the FairladyZ, so is this just another example of Wikipedia information being incomplete?

    If someone has replied to this query before with the information could you please paste the link? I've not found it in my internet searches thus far.

    Thank you.
    Last edited by Kerrigan; 06-21-2014 at 11:28 AM. Reason: added information

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    I think I saw some of the responses on your other thread. Some of the irritation might come from the fact that you're not including any of the helpful information from the other replies. You're ignoring what's been said and quoting Wikipedia. Maybe you could put some time in to compiling what you've learned so that people see their help being acknowledged. It seems like you'll keep asking the same question until you get an answer that you're looking for. "Describing differences" is very vague. What is the purpose of your question? Maybe someone can help you get their instead of citing differences.

    Tom Monroe's How To Rebuild Your Datsun Engine book says that the the L20A is a six cylinder engine that was not sold in the USA. There's a difference. The L20B is a 4 cylinder engine. The 1972 FSM shows an L20A as an option for the 240Z though, which seems odd if it wasn't sold in the USA. Maybe Canada got it. I included a picture of the L20A specs.

    I collected all of this in 5 minutes with my paper book and the internet. If you could do the same, people could fill in the gaps instead of starting from scratch every time you ask. What do you know and what are your sources.

    Just trying to help you out. Compile what you know and show it.
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    1976 280Z, with some minor modifications

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    @ Kerrigan, don't feel bad by forums contributors, forums are composed by all kinds of personalities , some are good nature and others are radicals in their interactions . Been fried by the in clan of a forum is the norm , so take it for what its worth . Good luck with your Z adventure.
    Last edited by Z fan; 06-21-2014 at 12:04 PM.

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    Here's another good source - http://www.nicoclub.com/FSM/Engine-S...gines%20EG.PDF

    I haven't seen any reference to an L20 engine anywhere yet. Only L20A and L20B. Your Wikipedia reference indicates that L20 and L20A are the same engine. So why would there be a difference?

    Seems like your real question is "where was the L20A engine used?"

    Again, just trying to help out. The answer to your question seems to be that there are no differences. They are the same engine. The A was added to show that it's the 6 cylinder 2 liter engine versus the 4 cylinder 2 liter enigne.
    1976 280Z, with some minor modifications

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    Thank you for the information.
    And I appreciate you reply; very civil and helpful.
    I have posted the information on our FairladyZ-L and it seems to incite so many different options about the car (and me) which has been good as it's caused me to keep looking for all the data I can find.
    And the confusion about these cars is rampant.
    It can't have the engine it has, it's number is "wrong for the car" and so on.
    It's fun, but confusing.
    I've had local Z "experts" look at the car when shown and tell me it's not original, that it's been "tampered with", has a engine that was not original, and so on.
    Had the car for over 35 years and know IT'S history being the 2nd owner since 1971, and always want to learn more about it.
    I'd be happy to learn it's a "factory fluke" or the ilk.
    Then, as the ONLY example left, it would be priceless :-)
    All in all, it continues to be a wonderful learning process and a barrel full of laughs over some of the "information" shared by others.
    Hell, even the books are wrong according to some folks, and the pictures of the car new must have been "faked" when published ... what a hoot.
    I just love the guys who say "the books are bull****, don't believe your eyes."

    One more time around the block:

    Manufactured as the Japanese Domestic Model (JDM) for the home market in Japan.

    Build window is May-July 1971 based on coded dates on wiring, fuel pump, etc. Total number of S30 models built in 1971 is 3,346 based on Nissan production records I've seen here and other sites.

    Luxury Model (suffix "L"), sub-model D.

    Equipped with original unmodified L20 2.0 liter engine coupled to original 5-speed manual transmission, ending with the original R180 3.9 ratio differential.

    L20 engine is 1998cc with 130bhp @6000 rpm, producing 128 ft lbs torque @ 4400 rpm.

    Listed top speed is 195kph with a dry curb weight of 995 kg.

    Full exterior restoration in 2007-2008 repainted in match to factory original paint Nissan 901 Grand Prix Metallic Silver, using original Nissan parts. Disassembled for painting except for engine unit.

    Interior remains original with original seat upholstery, has original factory option Hatichi AM/8-track tape player radio which still works and plays Steppenwolf just grandly.
    Last edited by Kerrigan; 06-21-2014 at 12:30 PM.

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    Nice manual ... note the cover does not list an L20 engine ... just an L20A ... with the single down-draft carburetor.

    I've never seen a manual specifically for L20 engine with the dual Hitachi carbs ... never.

    Do you know of one? I'd LOVE to see it!

    Like to find the right specs for internal parts .. like bearings, rings, pistons, and the like.

    Quote Originally Posted by Zed Head View Post
    Here's another good source - http://www.nicoclub.com/FSM/Engine-S...gines%20EG.PDF

    I haven't seen any reference to an L20 engine anywhere yet. Only L20A and L20B. Your Wikipedia reference indicates that L20 and L20A are the same engine. So why would there be a difference?

    Seems like your real question is "where was the L20A engine used?"

    Again, just trying to help out. The answer to your question seems to be that there are no differences. They are the same engine. The A was added to show that it's the 6 cylinder 2 liter engine versus the 4 cylinder 2 liter enigne.
    Last edited by Kerrigan; 06-21-2014 at 12:33 PM.

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    It's funny actually that Wikipedia has it wrong as well ... so much for those "experts" ... ;-)

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    Wait .. hold the phone ...

    How can the 6-cylinder be designated L20 if the "A" was added to denote the 6-cylinder from the 4-cylinder L20?

    Man, I'm confused! Geeze, what am I not catching on to here??

    Here is a for-real L20 6-cylinder dual Hitachi carburetored engine in the 1971 FairladyZ-L.

    Here's the stamp on the block. There isn't an "A" anywhere.

    Don't know what else to say, except "weird".

    Quote Originally Posted by Zed Head View Post
    Here's another good source - http://www.nicoclub.com/FSM/Engine-S...gines%20EG.PDF

    I haven't seen any reference to an L20 engine anywhere yet. Only L20A and L20B. Your Wikipedia reference indicates that L20 and L20A are the same engine. So why would there be a difference?

    Seems like your real question is "where was the L20A engine used?"

    Again, just trying to help out. The answer to your question seems to be that there are no differences. They are the same engine. The A was added to show that it's the 6 cylinder 2 liter engine versus the 4 cylinder 2 liter enigne.
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    Not to offend , Nippon send this car to this shore as an economical GT, there for all initial data is not that well documented as these tin cans are not an EXOTIC automobile .
    Last edited by Z fan; 06-21-2014 at 12:44 PM.

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    Quote Originally Posted by Kerrigan View Post
    Wait .. hold the phone ...

    How can the 6-cylinder be designated L20 if the "A" was added to denote the 6-cylinder from the 4-cylinder L20?

    Man, I'm confused! Geeze, what am I not catching on to here??

    Here is a for-real L20 6-cylinder dual Hitachi carburetored engine in the 1971 FairladyZ-L.

    Here's the stamp on the block. There isn't an "A" anywhere.

    Don't know what else to say, except "weird".
    I didn't read through all of your other posts but I do see that you might having some "cognitive bias" going on. You're interpreting things to fit what you "know" instead of changing what you know to fit the reality. There's nothing written anywhere that I see about an "A" stamp. Why would you need an A or a B stamped on the engine, all you have to do is count cylinders. So looking for an A stamp seems pointless. The A and B seem to be for documentation and manual purposes.

    The number on the engine would match the number on the body plate, in the USA market. I don't know if they did that in Japan. Is that where the "mis-matched number" thing comes from? It could just be a replacement motor.

    From your post farther above it seems like you just have a plain old JDM Fairlady Z with an L20 six cylinder. What's the big deal? The FSM shows it as a stock engine for the car. What are you really looking for?


    Edit - seriously, I'm just wondering what the fuss is about.
    Last edited by Zed Head; 06-21-2014 at 01:16 PM.
    1976 280Z, with some minor modifications

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    Yes. That's it. A plain 1971 FairladyZ-L with the stock L20 engine.

    You're correct ZH.

    I'm happy with that because, as you said, it fits my cognitive bias, which comes from looking at mine in the metal flesh.

    I believe it's the original engine to the car; the mounting fixtures and bolts and transmission bolts have not been removed. At least it wasn't swapped by the original owner nor me as the second owner.

    I have seen, in a posting, a picture of an 6-cylinder engine block stamped L20 followed by a number with an A prefix on the second number pad. I don't remember the serial number but it looked like

    L20 A12345

    So I guess that's what has caused the confusion, as I understood it to be an L20A engine.

    Can't believe pictures in books. The photo of the cockpit of a early FairladyZ-L (in Brian's Z book) shows a horn button without an image of a horn at the bottom. Mine doesn't have one either, but people insist it isn't correct. I'll go with the Nissan photograph. The one without the horn image is correct, but perhaps only in this year? Who knows. Not I for sure.

    One never learns anything unless one asks a question of more than one source (or Forum). I've changed my bias on a lot of things on this car that I though I had right, but others showed me where the information was incorrect.

    No fuss. Just Yankee curiosity.

    And again, thank you for being "nice".

    Quote Originally Posted by Zed Head View Post
    I didn't read through all of your other posts but I do see that you might having some "cognitive bias" going on. You're interpreting things to fit what you "know" instead of changing what you know to fit the reality. There's nothing written anywhere that I see about an "A" stamp. Why would you need an A or a B stamped on the engine, all you have to do is count cylinders. So looking for an A stamp seems pointless. The A and B seem to be for documentation and manual purposes.

    The number on the engine would match the number on the body plate, in the USA market. I don't know if they did that in Japan. Is that where the "mis-matched number" thing comes from? It could just be a replacement motor.

    From your post farther above it seems like you just have a plain old JDM Fairlady Z with an L20 six cylinder. What's the big deal? The FSM shows it as a stock engine for the car. What are you really looking for?


    Edit - seriously, I'm just wondering what the fuss is about.

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    You're good at writing on the margins. I can't tell if you're serious or not.

    Anyway, an interesting thread for you might be titled "Who has an L20 engine and what is the serial number, and year of car?" You might get a sampling of information that tells something. The picture from the past that you remember would be a start.

    I take it this is an argument about originality, and maybe value, of your 1971 car? Those arguments are served well by comparison with like articles. There must be others out there.

    There would be no good reason to mark your engine before the L20B 4 cylinder was planned for production. And, logically, you know it's not an L20B, and it is an L20, therefore it can only be an L20"A". Unless you're trying to find out when Nissan started marking A's and B' on their L20's, if they did. That would be a question that could be answered. Maybe go could out and find out what the 4 cylinder L20B's have stamped on the block.
    1976 280Z, with some minor modifications

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    Post #4 - Orange, and only a little rust: `76 710 - Project Datto - Ratsun Forums

    Implies that the format is L20X XXXXXXXXX, not L20 X XXXXXX

    I would assume that the format would be the same and would only be used when the potential for confusion was realized.
    1976 280Z, with some minor modifications

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    Here's one from this site that would be good to compare to (maybe you've already referenced it). With an A on the body tag. And some comments from your friend Alan T. Post #20 has the picture of the body tag. None of the engine though. Note that the OP does not say it's an L20A engine, he says it's an L20. Implying (to me) that there was no A stamped on the engine.

    http://www.classiczcars.com/forums/m...-rare-s30.html
    1976 280Z, with some minor modifications

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    Another - Post #6 (looonnggg thread). Again, no engine picture, just the body tag. By the way, could you link to your pictures for comparison? Might as well tie all of the Fairlady's together in one thread. Build your own case.

    http://www.classiczcars.com/forums/m...-fairlady.html
    1976 280Z, with some minor modifications

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    1976 280Z, with some minor modifications

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    Here's another Fairlady topic. More stuff.

    Fairlady Z ID help - S30 Series - 240z, 260z, 280z - HybridZ
    1976 280Z, with some minor modifications

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    Found this really interesting interview write up, The following is a professional translation of the article that reports an interview with Mr. Iida, the man that designed Nissan's first OHC, 6cylinder engine, the L20.

    Nissan L20 Engine Design

    And this one; interesting if you have not seen it already.

    Nissan/Datsun L Series Engines

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    That's a great idea, Zed. Thanks. No, I'm serious. Just an Irish/Scot and you know how we are ... at least the English do ... we never give up.

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    Since no one else has mentioned it, you might want to check out Carl Beck's website: the Z Car Home Page

    In particular, he has a history on the L series engine that makes for good reading.
    1971 240Z HLS30A 17574 L24-021025

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    Thank you. The cooling setup illustration on his site shows it's an L20A, stamped or not.
    That settles that question.
    Last edited by Kerrigan; 06-21-2014 at 08:31 PM.

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    Blue sent a link to the FSM for these engines which shows an illustration for the L20A engine as having a single down-draft carburetor; did it come in both this configuration and the dual Hitachi side-draft carbs?

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    Quote Originally Posted by Kerrigan View Post

    And this one; interesting if you have not seen it already.

    Nissan/Datsun L Series Engines
    By "cooling setup illustration", do you mean the water jacket outlet on the side of the head? You don't have that?
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    The L20A was also used on the JDM Gloria and 2000 models. These units were offered with the single downdraft carb.
    1971 240Z HLS30A 17574 L24-021025

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    I think that Kerrigan's quest may be to find out what's true and not true. How do you know?

    Lots of conjecture out on the internet. For example, all of my comments in this thread about no need for L20A until there was L20B are wrong, if the information in the links in Post #21 are right. Apparently there was an L20, then an L20A, then an L20B. Apparently, according to the internet.
    Last edited by Zed Head; 06-22-2014 at 07:05 AM.
    1976 280Z, with some minor modifications

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    Yes, the water outlet to the radiator is on the carb side, above the distributor.

    Quote Originally Posted by Zed Head View Post
    By "cooling setup illustration", do you mean the water jacket outlet on the side of the head? You don't have that?

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    That has been the frustration. The people whose opinions are respected and admired have offered up different answers, in good faith, which has made this been probably one of the most interesting quests for information I've ever embarked upon.

    It's been highly informative and interesting!

    "Enjoy The Ride"!

    Quote Originally Posted by Zed Head View Post
    I think that Kerrigan's quest may be to find out what's true and not true. How do you know?

    Lots of conjecture out on the internet. For example, all of my comments in this thread about no need for L20A until there was L20B are wrong, if the information in the links in Post #21 are right. Apparently there was an L20, then an L20A, then an L20B. Apparently, according to the internet.
    Last edited by Kerrigan; 06-22-2014 at 10:50 AM.

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