AK260

... it helped me turn back to being four years old again!!

Yes true!! Although the base already has a little indentation in it for something to go there I think! I will take a photo when I get round to doing it. Started the bearing job on the rear left yesterday. I’m using a stop watch for elapsed time as every 20 mins one of my kids comes out needing something and the half day job becomes a two to three day job! No one tells you this stuff before you have kids. I’m also experimenting with different rear silencers. The Z story classic straight through produces the best top end power - the engine positively sprints between 5-7k rpm. The turbo muffler on in the photo above does a great job but MASSIVELY quieter for long journeys although it robs the fun power at the top, given it’s more restricted.

That is very kind of you sir but please don’t go out of your way to do it. And thanks for tagging George Gregory Regina the third! [emoji106][emoji12] Look what I found In the plumbing toolbox ... And they are the EXACT dimension too for the job! I bought these as a mixed pack in 2002 when I was fitting a bath!! Amazing how things come back to usefulness! ;)

Once my needle work is complete (in the year 2031) I will defo hit the silicone! [emoji106] I’m quite please too and itching for the next shopping run and tinker - which these days is quite often with four of us eating at home and more than doubling the grocery throughput! I absolutely love the look of those round filters - they are phenomenally expensive to get this side of The Pond. If I buy from Zcardepot they end up at $239USD delivered!! As a matter of interest do you know the K&N part number (or dimensions) of the actual filter element? I am tempted to see if I can source the elements and fabricate my own metalwork. I know people say they will cost a few small ponies due to sucking warmer air but the sound is quite a way closer to DCOEs! These are several options but I think the E2410 is the closest! Also to be controversial, I have heard those flat tops can be great if you know how to setup / tune properly + maintain them. Thank you sir - very kind of you to say so.

Granny lot and others beat me to it. The 12si is a well rehearsed favourite and a CHUNKY bit of kit. I do hope you will up your compression and cam duration to carry the extra weight ;) Here’s another interesting link to read ... http://www.edmontonzcarclub.com/pages/articlepages/alternator.html

On my ‘77 260z I have the ratios quoted and a 3.54. It’s an absolute hoot for traffic light races as 2nd can take me to around 70mph so no loosing ground on gear changes. The drone zone on these cars is around 1.8k to 2.4k rpm give or take depending on your exhaust etc. I find at 50mph I’m square in the middle of that in 5th and often change down to 4th. Although with Sean’s Zstory Race/Sport set up the drone is 95% gone (compared with my straight 2.5” from header to rear muffler) but even then I just prefer to be closer to 2.5k. At 70 she is doing about 3kish rpm - I don’t fully trust my taco as I think it’s about 10% optimistic. Of course size of wheels has a bearing on this - I’m on stock 195 / 70 / 14 all round. I find 3.54 and that ‘box are a great compromise between cruise and spirited driving especially if changing up around 5.8-6.2k rpm which lands me exactly back to where the engine “comes on cam”. My diff is pretty worn so I’m about to go to a 3.9 especially as it would suit the characteristics of my modified engine better. Give that a 3.9 is 10.2% more turns of the engine for the same speed, all things being equal, you will dial 10% more revs and 10% less speed at the top of the gear change. The 3.36 by the same calculation is 5.4% more revvy so you will do 153 rpm less than a 3.54 at the same speed. You will nearly notice that on the highway. Now if you went 3.9 then you have a 16% uplift in revs which equates to 61.7% more fun! [emoji16] If you are city and highway driving but enjoy putting your foot down on the odd occasion, then your available 3.54 gets my vote. The L28 with a decent header should have a lovely wide torque spread but you get a bit more sports car for the money with the 3.54. The other bonus of the 3.54 is that it will make your gearbox “feel” closer ratio. Remember that gearing has a torque multiplier effect so it’s going to “feel” more like a sports car. Then sell your 3.36 to the drag racers who covet tall gearing! Sent from my iPhone using Tapatalk Pro

Captain, you never fail to make me smile!! [emoji106][emoji106][emoji106] I agree, on the move, when you get on the power you get the “spooling” whistle in the transition from steady to WOT! ;) The way I saw the imperfections was just with a straight edge (steel ruler), eyes and some sunlight. Enough came through to show me it wasn’t a perfect seal. I’m still not sure how or why it fixed it but I’m wondering if it’s a case of “managed” airflow v “unmanaged” at that part of the carb. Someone else suggested it may have been to do with me misaligning pistons before the gaskets went on - but frankly, those domes come on and off enough times to show such an error + I always do the full drop / clunk test with both at the same time to ensure 1. Each is clunking and dropping smoothly and 2. They both clunk at the same time - FBTT (Fast Brain Time Transform) analysis!

I did that too when my new engine fired up for the first time!!! Exactly like you, 30 miles later I was grinning from ear to ear but the whole time I was totally expecting to be stopped by the Police!!![emoji1787] Congrats dude!! Such a good win when that happens. That power band sounds great and tractable. [emoji106][emoji106][emoji106] I was told by my engine builder to check head-bolt torque and valve after the first 100 miles, 300 miles, 500 and so one while the head gasket and everything else settles.

Yes sir, that is the one I use. That, the AFR sensor and digital callipers I have found to be my best investments in carb tuning tools! In fact, the AFR is better than a Rolling Road IMHO as I get to see what happens in real world conditions. The foam probably squashed down to about half the size but that is actually irrelevant. Now, the height of the dome does not change the height of the piston as the piston sits dead flat in the middle of the gasket on the cab itself and freely slides up the dome. The only things affecting needle stations should be their mounting within the pistons and the jet heights. The silicone bead is a great idea! I used that on the carb insulators. I did consider it but given that my carb domes are off and on “more often than a tart’s knickers”, I wanted to have something constantly reusable. That makes two of us!!!!! ;) My theory is that the suck from engine side of the pistons was being vented and reducing the vac available to raise pistons, causing faster airflow velocity across the bridge and therefore a rich condition. But that is just theory. In an ideal world with more time I should have blocked the balance tube and measured vac before and after on either carb. I will keep an eye on this in case it was just a freak event and report back with any new findings. But I am curious as to why the carbs whistle so loudly now. [emoji848]

Oh and the whistle / hissing is even louder now - here’s a video of it!! Normal operation without air cleaner on or another leak now being sucked on even harder!? Place your bets!!!

Thank you sir, you are too kind. The ZT carbs I have don’t have the thing you mentioned above. I forgot to mention that the idle appears to have dropped by just over a 100rpm too - a classic sign of air leaks. This problem has cost me a lot of £££ revisiting the ignition system as it had all the symptoms of a broken lead/plug/coil/cap/rotor etc, but was simply an air leak. She’s flying like a scolded cat now and I can’t be more pleased - so what will I do? Tinker even more and break it again. Why break the habit now? I do want to experiment with different needles (currently KD, soon to be MC) to see if I can better the reversion part of the curve. My excel modelling tells me I will get a better all round mix with MCs. More of that on the link below if you’re COVID bored. https://zclub.net/community/index.php?threads/su-carbs-will-work-perfectly-on-my-modified-l28-and-give-dcoes-a-run-for-their-money.25839/ BTW I really did buy bread ... [emoji13]

So gang this has been driving me nucking futs!!!!! It keeps coming and going so I got down to business after homeschooling the kids today! I got a propane torch and unlit, I went around all the areas where it could possibly be leaking. Nothing! Then WD40 on the same areas. Nada! Then water mist sprayer and guess what? Zip! So next I got a length of 18mm ID rubber hose and listened around the carbs because the rear carb I thought was whistling loudly. Well both carbs are doing it and it was mainly at the mouth where the two small holes take air pressure to the piston. Hole 5 below. As I understand, SU carbs to make a high pitched sound without the air cleaner on. Next up, I took the domes off to see if anything obvious was amiss. All I could think of was that somehow the domes are leaking. I checked the bottom of the domes for flatness and found the rear carb in particular to be less than flat. So I got some 3mm closed cell foam sound deadening material and made a couple of gaskets. This made it way harder to centre the needles and pistons but a bit of patience and carefulness while tightening down did the trick. I went out to “buy some bread” and it’s a different car! The wobbly engine is a shed load smoother. The AFR that previously would not budge past 15 now goes 18+ on the overrun when in gear. The idle is sitting at a lean 16 and cruising steady throttle AfR is around 15-16. WOT when passed the reversion part of the range sits doggedly from 11.5-12.5, the latter at around 6.5k rpm. The rear wheels now squirm in 2nd at 4K rpm. So for now I am quietly confident the issue may have been resolved and will try to find a better solution with some plumbing rubber O rings.

FBT- - Brilliant!!!! [emoji106][emoji106] Agree - I hate constants like that without explanation. Here’s a site that does it for you. https://www.phormula.com/KnockCalculator.aspx So, 1800/(pi x 87mm) = 6.6kHz Knock sensors AFAIK are made with specific resonant windows and one of them has a centre freq of 6.5khz. Agreed. Again from my limited knowledge - they are fundamentally Piezo Electric, crystal based devices that output mV per gramme. I’ve asked myself this many times, do the extra 3-4 degrees of advance really make enough of a difference in road driving to justify all this hassle and potential risk? (Notice how I brought the thread back on topic! [emoji41][emoji38])

A knock sensor is basically an accelerometer that outputs a constant voltage wave relative to the acceleration - here is an actual plot, spot the knock ;) ... What I understand is that each one has it’s own natural frequency and so does your engine!! So the two have to be matched. The only way I can imagine myself doing it is: 1. Strap a sensor with a wide range to the engine 2. Log a shed load of data at various RPMs and load conditions. 3. Set the engine up to knock / ping gently and log more data. 4. Perform a Fourier analysis to then take out the background engine noise from the knock reading and isolate the key frequencies and amplitudes. 5. Build an Arduino to connect up and perform FFT whilst driving. The other way of course is to not get greedy with timing and leave it all alone!! [emoji1787] Edit: forgot to post this - the equation below pops up a lot on various articles about finding knock frequency - not 100% the way to do it but people who tune cars and set up custom ECUs claim it has worked well for them: Knock frequency (kHz) = 1800 / (3.14 x Piston Dia (mm))

Sorry guys I missed a bit of the part number - it should be: 22060-W1502

This is the best I could do with part numbers (22060) ...

From what I understand, modern cars are able to run super lean on the cruise and can get into AFRs of 18-20ish for fuel economy. Some are able to tolerate 60+ degrees of timing while cruising! To an L series owner that seems horrific but to modern head designs, coupled with knock /EGT / O2 / MAF / Air temp sensors and super fast ECUs etc it’s just BAU. No siree, I most certainly didn’t. The interesting thing is, having looked a little under the hood of the device and the app, it would be SUPER simple for them to add a data logging function to the app and if it took a signal from an O2 sensor (which is merely a 0-5v signal), it could provide a proper ECU-esque solution off a dizzy with 3D spark tables. In fact they use the GPS on the phone to get speed so they could just store the data and overlay on google maps for track days etc. But I guess they want to keep it simple for obvious reasons. :( I know this is off topic but out of interest, is anyone aware of a successful aftermarket knock sensor solution for the L series!? I know the 280zx had the first of such things but I’d love to get one on mine. JB started to build one but the filtering / testing was too hard without potentially damaging the engine. You need to detect the exact frequencies involved when knock happens - who wants to volunteer their engine for some Fast Fourier Analysis!? ;)

So come on guys, own up, which one of you was it!?

The 123 ignition I use, has a MAP sensor connected to the same place on the intake manifold as the vac advance used by the stock Datsun distributors. I’m currently running zero vac advance as my needlework is ongoing and while she holds a perfect 11.5-12 on the AFR all the way to the redline, she is running very rich on the cruise at around 12.8-14 (below 4K rpm) and 15 on the overrun. But once I get the next set of needles in and adjusted, I’m hoping for a leaner cruise of around 15; and 17-18 on the overrun, at which point I will be looking at about 7 degrees of vac advance max. Does that help at all?

I literally just did the rear bearings on my driver’s side and despite buying Timken off Rockauto, what came out of the Timken box has SKF stamped on the bearings for the outer ones and NSK for the rear ones! I stressed a lot about pre-load and torque. Turned out to be the grease seal causing friction and here is the thread with the problem solved ... https://zclub.net/community/index.php?threads/companion-flange-nut-torque-rear-hub-turning-force-bearing-replacement-on-my-260z-solved.26848/

Very very nice work!! Well done you. Would love to see how she goes when installed!

This war the supermarket queue eater day. After 25 mins and no movement I gave up and left. Can you imagine turning up full Darth Vader and standing there?

My new shopping look! Especially when someone coughs!!!!

Went for a walk today with the kiddies - this is our busiest motorway in the UK that is aptly named as London’s 8 lane orbital car park on any day and has constant traffic 24/7. It seems people are heading the government’s advice!! Very surreal - it’s like one of those apocalyptic movies where the population of the earth has been deleted!

Thanks for sharing!! I love the other open tabs!!! COVID 19, Face Masks, McLaren F1 engine! [emoji1787]