AK260

You are awfully kind sir, but I do feel like Eric Morecambe: https://www.youtube.com/embed/3OB3NE9-uMI

Great job! OK, first up the disconnected hose you are showing is a Positive Crankcase Vent (PCV) tube and when connected to the balance bar (the bit that is plugged) blow by gasses and hot oil fumes from the crankcase are sucked into the intake. You must connect that into a catch tank otherwise 1) it will eventually make a mess of your engine bay 2) it really is anti-social! ;) It’s not supposed to vent directly to the atmosphere My 0.3L catch tank was £20ish off ebay and works perfectly. It’s not this but it’s similar with a view tube so I can see how full it is. On this topic - trust NOTHING a PO has done, we all have different standards! That plug / grub screw may also not be fully sealed, so I would personally take it off, then use some plumber’s PTFE tape around the threads to re-seal it. Next up, you will find there to be a take off on the front carb that should connect to the distributor vac canister in your photo. It looks like this ... If that isn’t plugged you will be causing a massive lean condition at part throttle or idle - it may also be whistling loudly - reducing manifold vacuum by quite a margin. I was suggesting that you suck on the tube that normally would have been connected to the canister on your dizzy, but you don’t appear to have one. Finally - cue[mention=19495]Captain[/mention] Obvious to tell me I’m at the wrong end of the car or saying something that is “obviously” wrong! :p Edit: now this I’ve never seen before - is this little pipe some kind of USDM emissions type thing!?

Damn, you know me so well!!!! TOTALLY missed the fact that it was a front hub! Attention to detail - fail! I definitely need more sleep.

Gosh! Sorry to hear that, but at least it proved a point. ;) At present I’m planning on swapping the feed and return lines over at the tank end to prove it’s the pickup that’s my issue. However, when / if I do an elec pump, I am planning to ditch the stock bracket designed for the job and make my own anechoic chamber for it - read, metal “box” with screw on lid, lined with 10mm closed cell foam sound insulation and rubber isolation feet like these ... https://www.ebay.co.uk/itm/Rubber-Shock-Absorber-Rubber-Vibration-Isolator-Silentblock-Mounts-M6x20x15mm-/383835310627?_trksid=p2349624.m46890.l49292 I truly despise noisy fuel pump sounds!!!!

I just scrolled up and saw it. You did indeed - and in a far more eloquent / concise fashion. Geek alert!!!!! :p Ps. Insomnia is still sucking, large!

Will do. Been a tad hectic at home recently but will see if I can do it this week. OK, let me try to put my parents’ investment in my electronics degree to some use: you are basically correct even if you are saying it in an unconventional way. The circuit diagram I shared, while for a ‘70-‘73 model is basically the same in principle for all our “Smiths based” tacs (barring some small differences on the pickup side between the years). The inductive loop coil “pickup” (looks like a mini transformer) gets energised by ign coil pulses and creates a small current. The transistors you see are in what is typically called a “mono-stable flip flop” configuration. Let’s not get our minds twisted as to how the circuit works but in short, a positive pulse at the base of one PNP transistor turns it off which momentarily turns the other on - and so on - so it flips and flops from one state to another driven by the signal going high and low from the ign coil. But why do we need it you may ask? Well, the signal coming off the pickup coil is very weak and shaped like spikes. The flip flop circuit turns it into a square wave and it is effectively “amplifying” the current. That is a very crude explanation for the sake of brevity. The signal from the transistors provides a current strong enough to drive the coil of the needle. The electrolytic cap (the one with a + sign) is “smoothing” the pulses and preventing the needle twitching with each ignition event. You may know that every time you turn off power to an inductor, it flips it’s voltage to keep the current going the same direction before the magnetic field collapses - hence the configuration of that capacitor. I have to say, I’m quite surprised that a Zenner diode hasn’t been used to stabilise the 12v rail. Maybe it’s simply not been shown in that diagram. CO is spot on, those multi-legged components are packaged electronics. Right, I will shut up now and try to go to sleep! Insomnia sucks.

Firstly, don’t sweat it buddy, we’ve all done something like that. I used sockets too, you just got unlucky. Secondly, I erm, second what Racer and Zed Head have said already, I don’t think you’ve ruined anything either. The advice above is very sound. Finally, have you considered that it could be the metal guard on the flange? It’s a close fit and easy to knock out of round by accident! (See my dodgy red arrow mark-up below) Keep the faith, you will find it to be something very simple and insignificant.

Man if this was 3 years ago, I would have had this in a heartbeat! That’s a good deal.

Oooooh! Shiny!!!! [emoji106]

Right then chaps and chapesses (the latter clearly referring to Captain Obvious - the big tart playing with his shiny bits)! I took apart the Aussie pump I bought at a vast expense a few years back - this was the one that I thought had initially failed and swapped out for the original one on the side of the road. The diaphragm is utterly perfect and frankly I was impressed by the quality / thickness of it. The valves seal and release well and I can’t blow or suck through them in the wrong direction I gave it a suck and blow test with the vacuum gauge: it’s pulling 5-8 inhg and pushing 2.5-5 psi depending on how gently or vigorously it’s stroked. Here’s a video of the test in case anyone is interested in how well the mech pump, can blow ... (Forgive the staccato speech, weeks of insomnia is finally getting to me!) So it seems I need to turn my attention to a fuel blockage. I am getting black fish swimming around inside the filter and given that I replaced the fuel lines for alu with only 20cm of fresh rubber used, I am strongly leaning toward the POR15 treatment letting go. Some of it wasn’t flushed out properly by the PO and I wonder if there are lumps that aren’t fully set coming though? See the area where the float is sitting. You can see a black “eel” next to it before I flushed the tank. Also you can see a crater where the POR treatment wasn’t properly flushed out and has set. I would like to point out the soldierly self restraint exercised on a post so rife with innuendos! (“Oh matron!” You have to be old enough to know where that comes from)!

Spidya have a good selection of wav files for tuning their replacement electronics for our tacs. Download here https://www.spiyda.com/tacho-calibration-information Use your laptop or other device audio out to connect to your tac - not sure if our tacs are as sensitive but it’s worth a shot. And of course there is this .... https://onlinetonegenerator.com/ Ps. I have a tac that behaves perfectly until it hits 25-30 degrees C ambient temp, then the needle goes stiff. I think as they wear they need a bit of lube where the movement is. The rolling road guy told me it didn’t go over 5k rpm but in fact when the tac was cold and the throttle stuck on my old engine, it would happily find 8k! Strangely that engine produced lots of healthy torque after a few such events ;)

Thank you all for giving me lots to absorb and think about! One of my main requirements is a quiet pump - can’t stand the loud buzzing on some classics I’ve seen / heard running elec pumps! Interesting also that the K&N one appears under different brands - good to know it worked well. There is made in China and made in China - I guess the difference is quality control by certain brands and what can come out of the side of the factory without oversight. I received some AirPods I hadn’t ordered (long story), the box said price was $25 they were utterly identical to Apple ones - worked great for 12 hours!!! The BMW / RX7 pumps I like the idea of and will defo research more. I had no idea there was a fuel filter in the tank!! Being a ‘77 I’m not sure if mine has one or not. How on earth did CO remove it? When I put a camera into my tank this summer, I saw that the intake on mine was behind the baffle - did you take the tank apart? I was planning on leaving the fuel rail alone and setting the regulator to c. 2-3 bar to allow headroom for any pressure creep. Is that a bad idea? As for the facet pump and Malpassi regulator combo I found on eBay, Demon Tweaks in the UK is doing both for 1/3 less. It is perplexing why two pumps would fail in less than 500 miles of each other. I am wondering if the lining inside the tank is coming off and causing an intermittent blockage? Will take filter and one of the pumps apart this week and have a closer look. I worry that if this is the case, it will also cause issues with an electric pump. [emoji848]

Inspired by Captain Obvious, I thought I would go out for a last tango last night before they salt the roads. As it happens less than 1.5 miles in, accelerating off a roundabout at 2.5-3k rpm, the car suddenly lost power with afr at 18+ and struggled back to idling after pulling over. I suspect the diaphragm on my good mech pump has also started to go in the same way the other one did. Last time this happened I swapped the pump on the side of the road and it’s been perfect until now. I do have a NOS diaphragm, but I wonder if that will go too at some point. So I am looking at installing a tandem electric pump or possibly just going electric full stop. There are a number of options available but I’m truly confused what is best for performance and reliability. Planning on staying on the SUs so I need something capable of 3.5 psi or more and a pressure regulator. Or are there self regulating pumps that stay at SU / carb safe pressures? I like the idea of the K&N and it’s small foot print. What I’ve read says it’s quiet in operation too: https://www.knfilters.co.uk/81-0401-fuel-pump The NISMO was a nice option a few months ago when it was £80 on amazon but has now shot up to £180+ with import duties. So no longer as interesting. Then there are NISMO “looking” ones on eBay for peanuts. I can only assume these are cheapo Chinese items that will fail quickly. Or am I being bigoted? The Facet Silver top: relatively low pressure and time honoured use on Zs makes it an attractive option. I also like the Malpalsi fuel filter / regulator that would fit well where the current fuel filter resides - this eBay listing seems like a good combo - do you agree? Or shall I be going red top and pressure regulator? Wouldn’t it be a waste to have more pressure that I can’t realistically use with carbs? https://www.ebay.co.uk/itm/Facet-Silver-Top-Fuel-Pump-Malpassi-Filter-King-Regulator-Kit-up-to-200bhp-/121064855696?_trksid=p2349624.m46890.l49292 Any thoughts or experiences with these or other pumps would be greatly appreciated.

Ps. Just realised, I have a tech open already so I will have a look for you tomorrow if no one else has responded by then.

Ok, this is a topic close to my heart as my original rev counter would stick when hot and the second one has a tendency to bounce a little. So as far as I can see, you and I have two options: 1. Replace the electronics with this (which incidentally, would also give you a signal to plug into a data logging unit if that’s your thing or you ever plan to add an AFR meter and lose your life to tuning antics) https://www.spiyda.com/smiths-rvi-rvc-conversion-board.html 2. There’s a great thread here ... https://www.classiczcars.com/forums/topic/40718-tach-bounces-while-shifting/ And here’s the circuit diagram from it - given the symptoms you describe, I would wager that you are looking at the 500nf (0.5uf) cap on the pickup coil side: Finally, while you are about it, replace the electrolytic one also. They tend to go with age. Here is a great write up ... https://www.zdriver.com/forums/240z-280zxt-s30-s130-tech-tips-275/280z-tachometer-repair-40153/

Here it is in situ

I have a magnetic windscreen mobile phone mount but ironically I don’t use the magnet, the flexible but firm shaft from the suction cup to the magnet wraps around the gauge and holds it in place firmly. It’s like this one ... I found that a real-time view of AFR v what my right foot was doing was very valuable in learning what the carbs were doing at any given point. But anything other than in my line of sight, was making me take my eyes off the road too often and for too long. If I had a proper data logger I probably would leave it hidden and periodically, just pull over to play on a laptop.

Good job. In my books, it is the ONLY way to properly home tune your car and half the price of a rolling road. IMHO even better than RR as you see what the afr is doing in the real world under real driving conditions! I also installed mine into the glove box, but with long cables so that I could pull it out and stick it on the windscreen when I use it.

Thanks Racer - it’s good to have an experienced opinion on it. I also worry I have a slight leak still somewhere! You’re most welcome. Your compression readings are in the ball park for a stock engine and it’s good that she starts without issue. Assuming you are using the stock needles, I can’t imagine 1 turn down would be rich, if anything it’s a little too lean. I had a similar issue twice: first time, the idle was too rich and fouling plugs. Second time, the carb to manifold nuts were loose, causing an big vac leak. Oh and then I discovered that the diaphragm in my vac advance canister was completely dead, sucking air into the manifold! Have you checked the 4 nuts on each carb and all the manifold nuts for torque? Also take off vac advance pipe from the manifold side and suck on it to make sure you don’t have the same issue as I did. Finally, check the brake booster vac hoses to ensure: 1. You don’t have a split somewhere and 2 they are sealing with the jubilee clips.

Pa. this is an excellent resource to review also ... http://www.atlanticz.ca/zclub/techtips/vacuum/

I think it varies engine to engine depending on displacement, cam, compression etc. If it at all helps, here is what mine was doing ... Mine is 10.5:1 compression with a lumpy cam as you can see at idle. Here is a good guide ... Tell us more about your engine and it’s spec.

I hear you completely! I did this to start with so as to be able to identify all the bits afterwards .... ... but even then I kept not being able to identify other bits I had chucked in at the last minute! At least it’s a fun jigsaw puzzle with a beer in hand!

Absolutely right! Loving how that inspection lamp came out!!! I geeked out on my box of shiny bits ... Obviously my wife was delighted with me laying it all out and labelling on the kitchen counter! Does anyone else here think we need to get a life?

One assumes you are still referring to the de-rusting topic!? Otherwise, thank goodness!!! :o But then again, if that’s your bag baby, then bat on and hope for a good wicket old chap.

So with my solution, I dropped the parts into clean water straight away to flush them. Then I would drop them into a container of Jenolite and ensure all surfaces were covered. This converts the surface into something that turns it purple and supposedly doesn’t rust. The parts I didn’t Jenolite started to turn dull all too quickly as those pesky o2 atoms started to attach themselves!!! After the allotted time and drying throughly, I just painted them; as at the time we were in serious lockdown and I couldn’t get to the plating place.