HS30-H

I know it won't help much, but I've got a copy and can say that it's well worth having.

The passenger footrest was part of the original design and was standard equipment on Japanese market 'Deluxe' models (so Fairlady Z-L, Fairlady Z432, Fairlady 240Z-L, Fairlady 240ZG and on up through the years) and an extra-cost showroom option on 'Standard' models (so Fairlady Z, Fairlady 240Z and on up through the years). The mounts had reinforcing doubler plates spotwelded to the floorpan, and I believe these were on all Japanese market variants whether the footrest was fitted or not, as it allowed the footrest to be fitted at a later date. When they weren't used the factory just put rubber bungs in the holes.

With the caveat that some of the data supplied by Nissan Motors Japan can be wrong, depending on where it came from... I know Brian, and actually helped him in a very small way with his first book on the Z. I think it's fair to say that updates to his Z-related books could put right a few examples of bogus data, where known and recognised. When it comes to things like chassis numbers, it's probably best if we take the long-term view that we don't know the whole story and quite possibly never will. Data obtained or extrapolated from official and semi-official sources often conflicts, but the numbers on the cars themselves tell their own stories. There always seem to be exceptions that prove greater rules, and I guess it's not that surprising given the situation between Nissan Motors, Nissan Shatai and all of their suppliers during the period concerned. It's a little bit of a can 'o worms, and there's always a little bit of dirty laundry that certain parties (even 40+ years later) would rather we didn't see. There are a few skeletons in closets too...

That would make sense as a distribution number. It's the kind of data that would be really useful in helping us to understand what went where, and when, and I can't help feeling that somewhere - deep within Nissan's records - all this data exists in some form. It just hasn't been curated properly, and all the parties concerned (Nissan Motors, Nissan Shatai, the distributors/shippers and the local in-country Nissan organisation) haven't joined the wires together. Lots of data has been trashed/lost/misplaced, but there must still be a fair bit still existing somewhere...

The story is that the first proper batch of UK market 'HS30' prefixed Datsun 240Zs (apart from just two cars which came over earlier in connection with the Motor Show) was cancelled because it was found that they didn't actually comply fully with new legislation on front lighting. A hasty re-design of headlamps (incorporating sidelights) and front indicators (taking them out of the quarter valances where they were too low to comply, and putting them on top of the bumper) was undertaken and - allegedly - some of that batch of cars ended up in Aus./NZ. It's hard to judge how much of the 'diverted batch' story is true, but certainly the UK lighting compliance failure was a fact. And at that time Nissan's UK operation (Datsun UK) was being run as a franchised concession, and the concessionaire wasn't really all that interested in sports cars. He wanted cheap-as-chips little saloons to pile high and sell cheap... And yes, salty winter roads killed a lot of original UK market 240Zs. But most of those cars were going rusty before they even arrived in the UK, having spent days and weeks on the dock at Honmoku Wharf before spending weeks (up to 6 if they went around Africa the long way) in salty sea air on the boat. Yes, all RHD 'Datsun 240Z' models were 'HS30' prefixed, but - and here's the thing that a lot of people forget - not all 'HS30' prefixed cars were 'Datsun 240Zs'. The 'HS30' prefix was used by (L24 engined) 'Nissan Fairlady 240Z', 'Fairlady 240Z-L' and 'Fairlady 240ZG' models for the Japanese market between late 1971 and the end of 1973 too.

S. Africa is RHD and 'HS30' prefixed cars (not very many, actually...). I was trying not to forget S.African and accidentally lumped it in with the LHD market I was talking about. I've now gone back an edited to correct it. Sorry about the confusion. A bit of both, I think.

No. It would be madness to do that for all sorts of reasons. All the 'HS30' prefixed cars share a body serial number sequence, whether they were Export or Japanese Domestic market variants. Likewise all the 'HLS30' prefixed cars share a body serial number sequence whether they were north American market, greater European, Scandinavian or any other LHD Export market. As we know, no 'S30' or 'PS30' prefixed Japanese market cars were officially exported, and they didn't share their body serial number sequences with any other models. However, the prefix doesn't tell the whole story as there were sub-variants of each type (EG 'S30' and 'S30-S' shared a sequences, as did 'PS30' and PS30-SB') so that's where the suffixes come into play... I don't see any pattern in Export body serial number sequences. Body serial numbers were sequential in production, but liable to individual hold-ups (quality control/rectification) which could have made certain cars late onto the boats, and - anecdotally - things were a little bit fraught. Nissan Shatai were struggling to meet demand and the logistics of supplying a growing world market were causing all sorts of problems for Nissan. As far as the lower serial numbered 'early production' cars were concerned I don't think it's all that surprising to see them spread into several different markets when new. Dealers would have wanted at least one or two cars at first, and that's probably all they were able to get. Later it would have made sense to see batches of cars for certain markets going down the production line together, and I think that's pretty much what we see when we look back at it now. Quite often the cars went down the line in colour batches too, so not surprising to see sequential numbers in the same colour.

That's a big topic on its own, Gav. Still conflicting information and data out there, too. I've been trying to get a proper handle on it through Nissan and my fellow Club S30 members in Japan for a good few years now, as I'm particularly interested in the Japanese market cars and their serial number jumps. I know where most of the jumps are I think, but they don't always pertain to updates, minor changes or calendar dates. Might leave it for another topic if you don't mind?

The issue of actual build dates is its own can 'o worms. Can be especially tricky when it's to do with compliance/registration dates too. Officially Nissan had finished building HS30-prefixed cars by 11/73, so I assume yours is a compliance date or something like that? A few cars would get out of sequence due to quality control / rectification, so that muddies the water too. I'm just talking about the body serial numbers here really.

Ooh, that's good. Never seen that before. How complete might that be though? Any advance on 'HS30-103779'?

OK, who wants to play a spot of Chassis Number Bingo? We often talk about low chassis numbers, but what about the high ones? Question: What's the highest known body serial number for the 'HS30' prefix in Australia and New Zealand? As we know, production of the 'HS30' prefixed cars (that includes RHD Export 'Datsun 240Z' models as well as RHD Japanese market 'Nissan Fairlady 240Z/Fairlady 240Z-L/Fairlady 240ZG' models) ended before 1973 was out, but what was the highest 'HS30' prefixed body serial number? I've got some numbers for the Japanese market cars, but I believe some RHD Export market cars were still being made to fill late orders after the end of Japanese market car production. How high did they go? Over to you....

Hioki san is a friend of mine, but he has now left the Nissan group and works for JAF. I don't think he'll be able to help you. Honestly, I think you need to get old school on this. Forget e-mails. Nissan receives thousands of random e-mails every day and you're unlikely to get past the first few people who filter such correspondence. My advice would be to start through Nissan Australia (going over their heads may be seen as a snub) and if no joy there start writing letters (on paper) to Nissan in Japan. The guys who curate the collection at Zama (Safari Motors) really ought to be able to help with this kind of thing, but - in my personal experience - the top dog there doesn't know his arse from his elbow...

Yes I do, but in this particular case I recommend you start at the front desk and let them guide you through the system to the person they think will be most qualified and authorised to deal with the request. Short-circuiting the system can be a hindrance. If it's really as simple as getting Nissan to testify that they built and used such cars (something that we already know, and something that could be demonstrated in any number of ways - including the period Australian magazine articles) then it should be pretty easy...

As far as the HSCC 'Historic Roadsports' class in the UK is concerned, I believe that's not strictly the case. They are restricted the stock OEM front caliper and rear drums, but the rotors are free. So they widen the stock calipers with a machined spacer and use a vented rotor. Seems like a reasonable concession in the rules to me. The problem being - as far as I understand it - that those "new cars" were not sold to the general public.

My first mod of choice on an otherwise stock S30-series Z: A 4.44 ratio diff. No, really. Edit: And I know you're asking about engine mods here, but sorry I'd go for the diff ratio before touching the engine.

That's a sentiment I could share with you ad infinitum, but particularly when perusing some of the Facebook groups that are linked to our old car interests. They make me despair for humanity. So much for the much-vaunted "Information Age". The cost saved in not buying a KEW Twin Idler won't get you much bang for your buck spent elsewhere though, will it? Especially not with some "fancy" engine builder.

The same tricks that were being used by Nissan's works race engine builders soon after the L-gata engines debuted. There's very little new under the sun in regard to these engines.

I've seen and heard plenty of people dissing the Twin Idler over the years. Most of the comments wash over me and are easy to ignore because the source is obviously an idiot. But when the barbed criticism comes from someone I have come to respect, it jars. Makes me think there's something else behind it. Loyalty, perhaps? I've had exchanges with PMC Race Engines on HybridZ where Peter implied that the KEW Twin Idler actually cost power. He eventually withdrew the comment, but his reservations are clear. So, you pay your money and you take your choice. The moral is probably that you should go with the Guru of your choice, but don't try to mix parts, data and advice from more than one Guru or you'll end up making a cat's arse out of it all.

Gav, The S20 engine sounds like that anyway (late straight-cut gear driven oil pump type or not) because the cam chain tensioning system design is effectively the same as the KEW Twin Idler: It has two small rubber-faced static guides and two jockey wheels - one of which is manually-adjusted from outside the engine to give the desired tension. In one of Prof. Stephen Hawking's parallel universes there's probably a company making and selling simplified oil-pressure and spring assisted chain tensioner conversion kits for S20 engines because the chain doesn't whip around enough and it's too 'noisy'...

And one more thing. I see no reason whatsoever to buy Kameari Engine Works products from anyone in the USA. I recommend - if you are interested in buying KEW products, and have any doubts/questions - that you deal DIRECT with Kameari in Japan via e-mail (in English) and get the data from the people who understand it. They won't give you the Hard Sell, and they will try to get you to think of your engine as a coordinated and well matched package rather than a random conglomeration of parts. The (machine translated) quote from the so-called 'kameari usa' website further back in the thread says it all, really.

As per usual when this product is being discussed, people are talking mainly about one of the side benefits and not the main reason for its creation. I've been through this many times on other forums - in particular HybridZ - so this is Groundhog Day stuff for me, but as KEW don't tend to be invited along when their products are put in front of judge, jury and executioner I guess I'll have to take another stab at defending their creation and try to represent their side of the story. I used to visit Kameari's shop/office/workshop just outside Tokyo a real lot. I first started going there regularly in the late 1990s. Every time I was in Tokyo for work I'd jump on the train and go up there to buy a few parts, talk a bit, have a coffee and then jump on the train to get back to central Tokyo again for dinner. People would ask me to pick stuff up for them, and I would oblige as it was fun and interesting. I was always well received and we'd often talk about old parts and old times, current parts and future plans. It was around this time that Mori san told me he was developing something that he hoped would help to eliminate a phenomenon that they'd seen often on the engine dyno, and which was causing problems in certain extreme conditions. It was all about timing chain 'whip'; where the relationship between the crankshaft and the camshaft was no longer being controlled by the stock tensioning system and guides. Ideally (as in gear-train cam drives) the camshaft should rotate in a fixed relationship with the rotation of the crankshaft. This is fairly easy to achieve under constant or increasing engine speeds where the crank is 'pulling' the cam to rotate it, but in certain conditions (fast throttle-off, engine braking/deceleration) Mori san and his team noticed that the stock tensioner 'foot' (which is spring-assisted but mainly uses oil-pressure to exert a force on the chain) was being overcome and the chain was pushing the 'foot' back enough for the chain to 'whip' - allowing the relationship between the crank and cam to change. Obviously on interference builds this is not good, and pistons can come into contact with valves... They set up a few tests to see what was happening; One of these involved observing chain behaviour with the aid of a stroboscope. What they saw was a harmonic that could occur in certain conditions, and a 'wave' effect on the chain that looked - as they described to me - like the wave you could send down a skipping rope when you were a kid. In these conditions the stock chain tensioner system was being completely overwhelmed. THAT is the condition which the KEW Twin Idler was created to help overcome. All the other benefits (including the elimination of cam tower shimming on extreme shaved heads) are useful spin-offs that can help to kill two or even three birds with one stone. As it turns out, it's probably a fact that 99% of engines now fitted with the KEW Twin Idler didn't really need one, but so what? How are you going to police that? People will buy bolt-on parts and they will bolt them on. Most of them - as has always been the case with tuning parts - don't know what they are doing, and don't understand what the part is meant to do. A lot of the negativity surrounding the KEW Twin Idler stemmed from people not knowing what it was meant to do. They didn't have any problem with their stock tensioners and didn't suffer any ill effects from chain whip, so why was it created? They latched onto the quote of "13,000 RPM" and took the piss because they thought it referred to crank speed and some kind of promise of higher revs. They believed that it was being sold as a bolt-on power adder, when the maker claimed nothing of the sort. The manner of their criticism often revealed a hidden agenda and - interestingly - poked fun at the product rather than attempting to understand it. So when I see people describing it as "fancy" the old deja vu kicks in again. Personally I don't particularly like blue or red anodised finishes on anything except aircraft plumbing and centre lock wheel nuts, and polished alloy engine componentry doesn't do it for me either, but I realise KEW have to market and actually sell the products they make and that's what appeals to the main part of the market. If that part of "fancy" is what is being objected to then I agree, but it's easily cured and I know of more than one KEW Twin Idler that sits behind a stock inspection cover. I've stuck up for KEW and their Twin Idler for many years now mainly because I saw people who obviously didn't have the faintest clue about it trying to blow it out of the water. I felt like somebody should put across KEW's side of the story for the sake of balance. I've sourced and supplied a lot of them (used on street cars, and race and rally cars that have taken part in national and international events) but guess what? I don't currently own or use one myself. So buy one or don't buy one. Recommend one, or tell people they don't need one (most of the time they probably don't), but please do KEW the courtesy of understanding their product and the condition it was designed to eliminate. Thank you.

"Fancy"? It's not made out of pink chocolate with bits of glittery sugar sprinkled on it, love. Do I smell a little bit of 'not invented here' syndrome? Plenty of people were cynical and sniffy about the KEW Twin Idler kit when it debuted, especially some of the more - shall we say - entrenched of our American friends. I had a few exchanges with one guy who was under the mistaken impression that it would allow the chain to "twang like a GEEtar string". Apparently it was going to fall to pieces and cause engines to blow. The people coming out with all that at the time are pretty quiet now for some reason. Good luck trying to persuade people they don't need it, and should spend their hard-earned on something else. As a standalone (pretty much) bolt-on part for a set price you'll have trouble persuading them not to, I think. You might also be wasting your time telling them not to try bolting LHD-specific parts (like TWM inlet manifolds) onto the engines in their RHD 'shells, or "fancy" coloured ignition wires that are probably not as good as what they are replacing. Try telling them that their polished valve covers are a waste of time, and that their chosen wheel and tyre combo will make their car slower and handle worse. They'll ignore you. It's human nature. Unlike a lot of the 'tuning' stuff you can buy for these cars, the KEW Twin Idler had a reason to exist and does what it was designed to do. KEW don't tell anyone that it's something it's not. In my experience, they are honest and decent people. You should save some of your ire and sarcasm for the snake oil sellers who truly deserve it.

Indeed. Here's an LZ20B Turbo in the S110 Silvia Super Silhouette car:

Kameari Engine Works have always warned that their 'Twin Idler' cam chain tensioner is noisier than the stock Nissan arrangement. It's to be expected. Few people realise that the original L20 engine design incorporated a similar principle, and it was changed to the oil-pressure boosted 'foot' tensioner and long rubber-faced guides largely to make it quieter and more refined. KEW have never claimed that the Twin Idler kit is a power-adder per-se. Anybody who thinks it is should read the instructions again...

My - "overseas" - take on it all would be that pretty much anything demonstrably used 'in period' should be within the spirit of the rules, but on a case-by-case basis. But then it's not me you need to convince... Can we clarify, what is the cut-off date/period for 'period performance mods' in Sc please? Supplementary question: Is one of the problems here the fact that Group Sc is concerned with "50s and 60s" cars as per Mike260LW's quote from the CAMS manual? Over there in the UK when the HSCC's 'Historic Roadsports' category was initially set up, they would only allow 240Zs that had been built in 1969 to compete (they had a pre-1970 cut-off) which was a bit ridiculous and was eventually relaxed.