HS30-H

I haven't seen the magazine article in question, but I'm sure they made the best job of it they could considering their target readership and the resources they had at hand. Anybody making an effort to write about "our" cars is going to have to refer to previously-published works which quite often contain errors and misunderstandings. I'll try not to belittle their efforts, as I have personal experience of writing to a deadline and about something that one might not necessarily have an all-consuming interest in. You can't please everybody when writing articles like that. Hope nobody's holding their breath waiting for my labour of love. I'm still learning about these cars and I'm not smug enough to think I know even tuppence-worth about them yet......... I've been gathering information / pics / data / anecdotes and conducting 'interviews' with certain parties with regard to MY area of interest - which largely centres around the Works circuit race and rally cars and everything connected with them. Standard road cars - with the exception of homologation specials and other rare beasts including notable privateer teams and their cars - will not really figure. I think most of the standard road "Export" cars have had a fair share of coverage in any previous publications, so there's probably a case for leaving them out. It would however be nice to see a little more background on the actual PROCESS of putting a range of cars like the S30-series Z cars together. When Kats made his recent posts after talking to Nissan Shatai ( who made the bodies for our cars ) and to Matsuo san, I thought it was one of the most fascinating and thought-provoking posts that I've ever seen on this or any other Z site. I just loved to see Matsuo san's private photos of one the prototype cars, and Kats quoted Matsuo san on a few specific details which were enormously interesting. It was like looking through a dirty window into another altogether unknown world. To me, that just brings home the fact that SO LITTLE detail about the evolution of the cars that we love ever seems to be published in the English language ( or any other language apart from Japanese ). Considering so little of the actual background seems to get written about, its an added frustration that what little DOES get published always seems to contain oft-repeated errors and plain inaccuracy. If I eventually end up publishing, it will almost certainly be classed as 'Vanity Publishing' - with a very small run and a relatively high price to cover costs. Picture clearance is one of the biggest obstacles, as I have put together a pretty good collection of rare pics but one needs to get clearance from the copyright owners to use them. Like I said - don't hold your breath. This may be a lifetime's work. All the best, Alan T.:classic:

Hi Victor, Well, the plumbing sounds correct - so that should eliminate my questions on that issue. As far as I am concerned, blocking the return feed to the tank is important - so that's good news. Getting proper "O"ringed gaskets between the carb bodies and the manifold, and their correct rubber or spring washers, is going to help with insulating them from heat soak. Keeping them slightly 'loose' ( but still leak-tight ) against the manifold is going to protect from frothing which can occur at particular frequencies depending on the characteristics of your engine. Hopefully that insulation your are carrying out will make a great difference. Good luck, Alan T.

Hi Victor, Glad you won't ( can't ) give up on the Webers. I guess you would be right that it would be most unusual if all the floats all stuck at the same time - but seeing as you rebuilt / refurbished them and set them all up the same way, then it is always possible that the same problem might affect all three carbs. I have never had a problem with using the original brass floats, as long as they are in good condition - like you found that yours were. What's foxing me is that the problem was cured when you manually put fuel into the float bowls. That would suggest a fuel-feed problem stopping fuel from flowing normally into the float bowls. If all else is correct, then the floats and inlet valves are what control this. When I say all else correct, I mean that fuel is flowing as far as the inlet valves at the correct pressure and the right volume. If its not, then it could be due to any combination of the possibilities previously discussed. What's the schematic of your plumbing? I think this is an area that can cause any number of problems. Nissan's own Sports Option parts included a special hard line fuel supply rail to replace the one for the stock SU-type carbs. This special line was just a single pipe ( fed by the main fuel supply - ie any correct pump but preferably the electric pump ) and it had three branches off it - one to go to each carb. There was no return to the tank, and you needed to block off the return line to the tank down by the stock fuel filter ( otherwise you would risk overflow from the tank under extremes of braking / cornering and overfilling ). The Webers and Mikunis usually seem most happy with a good constant feed of around 4 to 5 psi and with the necessary volume to sustain that pressure at full load in top gear. I'm just wondering whether your plumbing is allowing vapour lock or percolation that is blocking fuel feed to the carbs and the fuel is being pumped straight back into the tank through the return line? Blocking the return can sometimes alleviate vapour lock. You do indeed need some kind of insulation between the carb bodies and the inlet manifold. On Webers ( which are prone to frothing under extreme vibration ) it is usually recommended to go with an o-ringed type of gasket. This allows a certain amount of flex between the carb body and manifold, and the carb is never fully tight and hard against the manifold. The nuts that hold the carb bodies to the manifold usually have rubber or spring washers under them to keep this flexibility. Without the proper gaskets you run the risk of significant temperature bleed from the head / inlet manifold, and fuel frothing in the carbs. If you want to take this further, can you describe or illustrate your plumbing layout? I still think this might be at least partly to blame. All the best, Alan T.

Hi Victor, Sorry to hear that you are having problems......... I remember a while back you were asking for information on getting the Webers dialled in and jetted properly for your high altitude. Did you ever get the engine running correctly? I think I remember pointing out to you that a trip to a rolling-road dyno for a proper set-up was probably the best way for you to get near to the jetting that you need. If the dyno was down at a lower altitude than your normal driving environment then some compromise would have to be made - but a good technician would be able to give a pretty good estimate of what was needed if he knew the normal range of barometric pressure for your home area. I don't want to be devil's advocate here, but did you really satisfy yourself that the carbs were correctly assembled and had all the right parts inside? I seem to remember that they might have been something of an unknown quantity ( no? ). Your mention that pouring fuel directly into the float bowls will help the engine to start almost immediately is very strange. That would suggest to me that you have a very simple float-sticking or inlet valve-sticking problem that could be temperature-related. Indeed, as everyone else has suggested, it could also be related to a vapour-lock situation. I'm also wondering just how your plumbing is connected up. Are you still using the stock fuel rail and the return-feed to the tank? Are you running an electric pump, a mechanical pump, or both? As has been suggested, at least a proper heat-shield would help a great deal once you got the car working right. You can make a good one yourself out of ally sheet. I personally use header wrap and an ally heat shield, and I've never found that the header wrap caused me any problem - although the ambient temperatures here in the UK are nothing like those in America or Australia ( although curiously its 36 Degrees here in central London today! ). Any vapour lock or percolation problems that I ever suffer from are due to diff, transmission and engine heat transferring into the fuel line as it runs up the centre of the car. When I'm running at a normal speed ( anything other than a crawl in fact ) I find that the fuel runs up the line fast enough to avoid being too heated by the time it arrives in the actual engine bay. If I were to stop in traffic for a while I might find the engine starts to stumble and shows symptoms of running out of fuel. Greatest danger of vapour lock and percolation is when stopping for more fuel after a good run; I can get back in and start up but after just a few feet the engine can cut out dead. Quick twist of the key with no foot on the throttle and it clears instantly. This is evidence of vapour lock and fuel vapourisation / percolation in the carbs............. Its very frustrating to think that I might be able to diagnose your problem or at least make it a little better if I could only have it in front of me. Trying to diagnose this kind of thing over the web is notoriously difficult, and in the end you really could find a more simple problem is causing the same symptoms ( it could even be electrical! ). Sorry I can't be of more help, but I really would suggest that you might like to think through your plumbing and fuel feed / return just to eliminate any possibilities there. Above all, I don't want to see you chuck in the towel and damn the Webers as the instruments of the Devil. I've seen this happen too many times, when in fact it was incorrect installation / tuning / jetting / set-up / plumbing that was to blame. I know, I've been there and made all those mistakes myself........:cheeky: All the best, Alan T.