'73 Z with a L 20 block & Y 70 head help

[beandip]

does any one have knowledge of these two items . A member just bought a 240 with this combination and it is a strong runner . So far no one knows any thing of the head at all and that the L 20 might have come from a Fairlady . Vary uncommon here in Portland !!!! No it is not a 4 banger. if any one knows anything of either the head or block please post , thanks beandip

[beandip]

It seams that the L 20 is a late model engine that uses the Y 70 head and is a high reving engine but of 2000 ccs, this info so far came from a member in Austraila

[zerozero]

I have a 1978 260z with the same combo They were made for the japanese domestic market, as were alot of 280z's. Fuel injected very smooth and economical, 145Hp on the engine discription plate.

[HS30-H]

Hi Beandip,

I already told both you and the owner of the car what that is, both in replies to your original posts and in PMs and direct e-mails to both of you. What's changed since then? If there is something specific that you want to know about, then let me know and I can maybe help you - but other than that, as I told you before, its nothing "fancy"................

The L20 was offered in countless different versions in many models other than, and as well as, Zs for the Japanese home market. You should not be surprised that it revs so well - it has an extremely short stroke! The Y70 head is nothing special ( as I told you before ) and in fact is not even one of the desirable heads with more performance potential; its a fairly late iteration of L-series head that was low-emissions related, and not a hot tip for tuning work. The earlier L20 with the E30 head has a better combustion chamber shape.

I have always been slightly irritated that people tend to dismiss the smaller capacitied Japanese home market Z engines as vastly inferior, even though they usually have never driven one. In fact, many of the higher-spec. Japanese S30-series cars with the L20 engine and five-speed transmission drove better than the USA / North American spec. models ( which lost all their 400cc advantage by mating it with a four-speed and a very low diff. ratio ). As you say, the L20 can be very revvy - and this can be quite a sporting characteristic with a relatively close-ratioed five speed trans. and 3.9 diff. ratio.

Don't forget that the Japanese home market also had the choice of the L24 engine from October 1971 onwards. That left them with a relatively wide choice of Z variants from cheapo L20 and four-speed equipped "cooking" models with no carpets or hubcaps, right up to the 240ZG and twin-cam 24 valve S20-equipped Z432. That's quite a different situation to the rest of the world, which tended to get one market-specific model and no choice other than paint and interior colour. The USA / North American market version looks quite a spec. compromise in this light, with its 4-speed and diff. ratio................. ( its hard to resist the temptation to poke a little fun at this version whenever the opportunity arises ).

There is a lot of disinformation and ill-informed hearsay out there in cyberspace about the rarer variants of Z engine. I was absolutely amazed to read on the HybridZ site that people were posting nonsense about the S20 and LY Crossflow engines, and the O.S. Giken TC24 twin cam conversions. These ranged from posts saying that the S20 was a twin-cam cylinder head that Nissan put on the L20 block ( totally wrong! ) to comments on the LY Crossflow head being a twin cam ( it was a single cam ). They even get all three mixed up and nobody sorts it out for them. All this must have come about because there is very little literature out there for people to learn from; any Z-related books or magazine articles in the English language are usually poorly researched when it comes to these rarer variants, and these are usually the very writers who dismiss the 2 litre engines as some kind of inferior nails.

If the engine ( or whole car? ) came from Japan in anything other than "new" condition, then it may have been improved or rebuilt over there with a compression ratio increase and / or a camshaft change. This is quite often enough to wake one of these engines up and make it seem quite peppy.

But if you think its something special, then think again. Sorry to repeat it - but its actually quite "normal" in Japan..........

Regards,

Alan T.

[ZmeFly]

[halz]

write The Book, Alan, write THE book!

[Saint]

Ditto!!