AK260

I am about to do this job and was going to use EP2 grease which is the same that I used on the bearings. High temp, designed for high speed / sheer conditions ... https://fuelandfriction.com/weekend-warrior/ep2-grease-part-1/

Quiet the contrary old bean! The “superior” :p late (‘77/‘78) 260z had many improvements over the early ‘74 260z. In between we got the 2 by 2 version. It has the stiffer unibody, the fatter chassis rails / floor supports that go all the way back, suspension improvements, the hubs are bigger, 3.54 R200 diff, better torque spread and 161bhp on a more tractable engine, a more plush interior, different wiring loom and so on. On that note, my old L26 would pull strongly from 1100rpm in 5th all the way to 5.6k. It’s a shame we didn’t get the 280 engine - without the smog stuff it would have been a very decent bit of kit. But the UK had protectionist taxes in place so they were expensive compared with British Layland cars and we got, relatively speaking, very few S30s. So very sadly we have to go to US / Japan for parts and still pay stupid import duties of about 30% on the parts and the postage + the obligatory £8 handling fees!!!!! It is lighter than the 280z but I guess the 280 got aircon, a plushur interior and those “robust” bumpers etc. I’m sure there are many many other things I have failed to mention, but at the risk of being a heretic, it’s mechanically closer to the 280z than the 240 from what I have seen. But no secret hatch in the boot!!

Alright gang, the hunt for air leaks continues .... I could tell that despite the car feeling better, there was still something amiss with the rear carb. Using self penetrating oil (as it froths up nicely and is runny), I sprayed around the typical areas and found that that outer end of the throttle shaft on the rear carb was showing a perfect line in the froth between the end cap and the carb body. Using a razor blade, I gently encouraged it out (which was frankly quite easy). I discovered a putty type material in there which I assume is there to seal the cap. Not much of it left though. Looking at the fingers in the cap, you can see where it was leaking has the dark residue. So I cleaned both the cap and carb big up and using a gasket making paste, I covered the cap, pushed it home and wiped off the residue. I’m sure someone will tell me that I have used the wrong paste ;). Incidentally, I used the same thing on the intake manifold and carb insulators gaskets to ensure a good seal. I then did the other side to play it safe. Having given it a good hour to set, I fired up the engine and did the same test, froth everywhere! So if your ZT carbs start to leak, at least the fix is very quick and simple. Mine have been on for 7 years at an average of 2k miles a year. So I guess it’s fair to expect a little maintenance being required.

Thanks for sharing CO!! I envy that hatch - my ‘77 260z doesn’t have that! I’ll take a photo of mine tomorrow and share - the connectors are different to yours and awfully crusty!!! The are positioned perfectly for being splashed with road crud. Also we didn’t get fuel warning lights in Europe so my connector is just like spade connectors. I will have to pull the tank or some tubing as the small fill up today resulted in a lot of smell inside. Also going hard on the anchors did the same so I suspect something has come lose or given up the ghost.

Here’s the C cam on a ported E88 head atop an L26 with MSA 6-2-1 header and 2.5” pipe back to a turbo muffler. Stock compression and 280zx distributor with Pertronix flamethrower 1.5ohm coil, Z therapy SU carbs on SM needles. Engine was burning a fair bit of oil but look at that gorgeous torque curve!!! Driving that engine was an utter delight!!! It wasn’t massively quick but you were never short of response or torque.

I hate it when that happens - it means I didn’t learn something new. Although I also fear that years of marriage have taught me that it’s better to be wrong even if I am right! [emoji12]

Are you sure they weren’t SM needles? I may be wrong but I understood they shipped SM by default on all their rebuilt carbs. [emoji848] Interesting how different engines can respond. I found the SB going very rich on my engine. Way too lean at idle if I was to dial them back. Doing this you get very hot idle which in my case is bad as queuing on the motorway or at tracks etc on a hot summer day is a regular occurrence. I also suffer with horrible reversion around 3.1-3.5k rpm so the SBs just didn’t work with my car. There is a chap who posts on youtube with a stroker - he says they work very well for him. But I’m guessing a 3.0 high comp engine needs more fuel than my high revving 2.8 that is still building power at 6.5k rpm. The thing with making a rich needle leaner to make it work better at WOT is that not only can you get lean idle but I found it ruins the quality of pickup and throttle response. So here’s the thing about dyno runs: my tuner spent 4 hours re-profiling my SM needles that came with the SU carbs. He told me it was going very lean at the top so he backed off and apparently I need triples to get the fuel flow. Actually, on the road at WOT I have never been above 12.8 AFR - why? Because to get to the same conditions he did I would have to be flat out in 4th at 125MPH. I may see that on a race track straight but never on the public road. Flat out in 3rd, uphill on the local motorway at 22:00 when it’s virtually empty is my free dyno time ;) I used KV needles to prove that the fuel flow wasn’t an issue and could happily hit AFR 10s at the top end with jets only 1/2 mm down. So fuel delivery wasn’t the restriction, lack of a properly profiled needle was! Oh and an air leak on the carb insulators that went undetected at the time (but at WOT the effect of that would not be dramatic). So began the obsession with needlework and simulating before buying. At £25 a set it very quickly gets very expensive to do it by trial and error. The AFR meter / sensor was the best investment I ever made for tuning. Because I see real world AFR and carb response with different ways of using the throttle in normal driving not just simulated WOT. I would love to as I see this as open research for the Z community at large - but I am hesitant to share quite yet. It is currently not at all user friendly - you have to understand how it works to make it work. Once I have it all tied down then I fully plan to share. However, in the meanwhile, I would highly recommend this site: Http://www.mintylamb.co.uk/suneedle/ Drop in your reference needle, select a second needle and use the up/down scroll bar to quickly scan through profiles. It also allows you to download ooodles of profiles (which is where my unhealthy excel based obsession started)! Again, I would urge any needle changing to be monitored with an AFR meter in real world driving. Are all the engines mentioned above running well with SBs totally stock and on stock headers or something else?

So gents - I have a small unhealthy SU and needle work obsession and spreadsheets that do all kinds for me. Here is a plot of the “annulus” area (jet opening) with the needles discussed and the SMs that come with the ZT carbs. I’m currently running KD but soon to test MC. But my engine is very modified. Hope this chart helps with your deliberations!

Utter genius captain!!!! I have saved it for future ref. [emoji106][emoji106][emoji106] It also shows me that I have some additional impedence as mine never quite gets to F even with the breather hoses in tact and the fuel all the way up the filler neck. Then again, the PO wasn’t into cleaning contacts when he did things. One to look at for me on my next Z play date.

Tried it all, but to no avail! It’s basically to do with the length of the straight part of the S pipe I have on. The old one that came with the car is just an inch longer and allows greater flexibility. Is it mated to an L24? I have heard that the L24 with this setup generally doesn’t suffer with drone. My L26 with just head porting did but it was very tolerable. My modified L28 on that exact same setup transferred post engine transplant was totally unbearable between 2-2.5K rpm and just had too much bass everywhere else. It took the joy out of driving for anything more than a 15 mins blast.

Perfect thank you!.

Looks like a perfect fit! [emoji106] As a matter of interest, what length of resonator did they put on? My old MSA header and 2.5” pipe work could accommodate the turbo muffler horizontally. The Z story one has a slightly shorter straight on the S pipe so a turbo muffler has to fit sideways or vertically, neither of which I like very much. It makes the car look like it has low slung “old man balls”!! I keep switching between the Z story classic straight through and the turbo muffler for experimenting with sound levels. Clearly the Zstory is better for top end power as it flows much more freely. It sounds very NASCAR at 6k+ RPM when the sound is bouncing off the central reservation barriers! [emoji41][emoji16] Now on flow directions. As you know, the turbo mufflers are of two kinds inside; 1. Those with three perforated pipes. Some have a curved piece of metal inside at one end to better direct the flow and some just bounce it off the end of the box. The former has better flow in the direction it’s meant for. The latter can be used both ways. 2. Those with baffles that bounce the exhaust about inside. Depending on the design these have direction for the reasons above but some tend to be unisex. This video does an admirable job of showing you the different internals and sound comparisons ...

They will look fab on your car!! [emoji106] Will 8” fit without rubbing or arch work? I had no idea you were in Sweden! I worked for a long time in Kista (Ericsson). Absolutely love the Swedes, one of the planets loveliest cultures I’ve had the pleasure of experiencing. It summers were crazy bright - I always thought that as an adult I can just use a clock for going to bed when it’s still light outside at 22:00, but no! Just partied like the rest ;)

That’s beautifully flat for rattle can work - nicely done sir. You are lucky! I virtually never take my Z out in the wet - although in Britain we get caught out quite a lot. One moment sunny, next minute you are worrying about the car dissolving ;) What wheels are you aiming for? I do like the ones you have been painting.

Those wheels look great dude! Did you use a proper spray gun or rattle can? BTW 7 year old tyres! Are they still gripping OK in the wet? Mine were truly gone at that point even with 6.5mm left. And yes I had a VERY big scare one wet day.

What think yea wise ones, is this idle vacuum behaviour normal for a lumpy cam or should I be looking for another air leak? Interesting the same test before my homemade gaskets didn’t go over 50KPA but now hits about 75. So I was loosing vacuum before. But it’s the idle thing that has me thinking. https://youtu.be/n2dLeRsJxT4 Edit - part of the reason I ask is that going from a turbo muffler back to the straight through made the AFR lean everywhere expect for WOT and the reversion points where it became even richer on the latter. I am wondering if with less back pressure, the engine is able to suck harder and finding another leak I haven’t yet found? Or is this wobbly vacuum at idle a feature of higher duration / lift cams?

Yes that does make it more difficult. I will try to take a photo for you with a tape measure in it. IIRC there is quite a lot of space up there. The only thing to think about is how to get it far enough up the well to not get kicked. Also as your car is already apart you are able to easily weld brackets or mounting points. One of the things that slowed me down was the fact that I will not add holes into my car by drilling the bulkhead. There is already a mounting point for the blower motor, which I intend to piggy back onto with a home made bracket. If you’re clever about it, you can design a bracket that soars high up in the footwell but can be unclipped to point down / come down to be easier to deal with on a dark night. You could even install a low wattage light / led over it to come on when needed, negating the need for a torch. You are absolutely right about the mini relays. The other thing to possibly consider are the fused relays which means each relay has it’s own fuse and negates the need for a separate box and associated wiring, see this ... https://www.12voltplanet.co.uk/make-and-break-relay-normally-open-contacts-12-volt-30-amp-integral-blade-fuse.html

Nice work ET[emoji106][emoji106] I really like the low oil and coolant warnings! That sounds like a big job but a VERY worthwhile thing to do. I have been (for 5years) planning - but not for round to it yet - to put a combined relay and fuse box in the passenger side footwell close to or above the blower motor so that it’s accessible and hidden. Would that work for your fuse box? You wouldn’t need to modify the seat then.

At the risk of stating the obvious, don’t forget all those charts are showing alternator rpm and if you are using stock crank pulley at 150mm and stock alt pulley are 75ish, your alternator is spinning twice your rev counter speed. One other consideration which I’m sure you’ve thought about is to upgrade the wiring to cope with 140amps. In the real world your alt will not be pumping out 140amps constantly unless you have a flat battery and revving hard. But your 40+ year old wiring rated for a 40A alternator with headroom won’t be man enough - the last thing you want is a car-b-q! Although your fusible link “should” blow before that happens. I had my 280zx alt rewound for 90A. Rather than replacing the wiring, I doubled it up by running a parallel cable back to the battery with its own fuse. That way you avoid running silly large cables under the bonnet.

That’s a great outcome! Very pleased for you. [emoji106][emoji106] My L26 had a beautifully ported E88 head and went so well. These cars seem to love a good bit of porting / matching.

I have to agree with you on this. My L26 had MSA 6-2-1 header + 2.5” straight back to a turbo muffler. Sounded awesome. There was a drone at 2-2.5k rpm but bearable. Then upgraded to an L28 and the drone with the same system was unbearable on a long run or while cruising about. The ZStory exhaust with a rather long resonator all but eliminated it to about 80-90% less drone. In addition to displacement, i do think that the cam overlap and lift has a lot to contribute to this annoyance. Also advancing a cam will make it louder. But I won’t run my L28 again without a resonator. Did your L28 have a hotter than stock cam?

... 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! ;)