AK260

Actually dude, reading up the thread and thinking about this again, I think you would do well to replace the valve seal on no.4 WITHOUT taking the head off. One of my friends in the uk just did this on his L28 and it was a piece of cake!!

Ok, so you are eliminating many of the possibilities which is great. What I’m not getting from your replies is: 1. Have you tried a different cap and rotor? 2. I don’t know what a “hitachi single” means - can you elaborate please? Is that a conversion made to a points distributor to make it electronic? Do you have access to another distributor to drop in and test out to eliminate your dizzy as a possible culprit?

Someone in the uk is looking for exactly this!! I will forward to them for you!

No offence taken! Bojo the clown is a very intelligent man who looks like a clown and whose moral compass only points towards the direction of his own personal gain! Much like many other politicians worldwide. Back to the original post, I am still intrigued by this car. It simply defies logic at that price.

OK, that's good. So, the way I see it is this: 1. It's not oil on the plug itself 2. Your coil is healthy and your mix on that carb is OK as the rest on that bank of 3 are not getting fouled the same way 3. I am making an assumption without reading up the thread that you have done your valve lash adjustments and that they are consistent across those three cyls. 4. I think I recall you doing a compression test showing no.4 is pretty much inline with the rest in compression, so you don't have compression issues or valves leaking issues. Assuming this is an electrical issue (which is what we're left with after discounting the above) and also assuming that all three plugs in your photos have the same heat rating, you need to identify why that one isn't getting enough spark / energy for a full burn. Some thoughts: a. The spark plug itself: Have you tried swapping one of the other spark plugs into cyl 4 to prove the plug itself isn't the issue? Let's prove the spark plug itself doesn't have a hairline crack or other issues. Does no.4 always foul regardless of which plug is in it? b. Ignition leads: Have you tried a different set of ignition leads or swapped, say no.4 lead with no.3 lead (both on the distributor cap and at the spark plug) to ensure the lead isn't at fault? - I once had a Magnecore KV85 lead with intermittent issues (after 6 years) that had the same symptoms as you are experiencing. It drove me nuts until I found it. I only discovered the issue after bench testing. In the car, it's very difficult to tell if it's firing ALL the time - our eyes are simply not quick enough to see it. But on the bench with an ohm meter connected to both ends, I could see the resistance changing from tens of KΩ to hundreds of MΩ when I wiggled it. When I raised it with them under their 10 year warranty, the owner at Magnecore was just unbelievably condescending, claiming it's impossible for their leads to fail and it's always the customers' fault for not unplugging the leads regularly!! Gobsmacked, I didn't waste my time and money sending them back and made my own for a fraction of the cost - not only do they fit perfectly but they have worked flawlessly since. - Also, does the HT lead "click" as you push it onto the spark plug terminal? Make sure you have a good connection. On that note, inspect the HT lead for signs of corrosion / arcing. When a spark jumps a gap between the lead contact and the spark plug terminal, it leaves a powdery white / greenish residue on the HT lead contact. It's a sure tell-tail sign of spark jumping rather than a good conductive connection. c. Distributor: Have you inspected the inside of the distributor cap for any damage on no.4 or any obvious signs / issues? Have you tried a totally different distributor cap? Is there any wobble in the distributor shaft that may be consistently affecting no.4 (this is unlikely but worth a check)? In fact, what distributor are you using? Are you on points or electronic ignition? If on points, could the dizzy cam be worn for no.4 and causing less "dwell" time? d. Spark plug seat on the head: Have you cleaned the threads on the head? Sometimes, when the heads are painted, you can end up with paint on the spark plug hole threads / seating area that causes resistance, reducing spark energy. This is unlikely but worth eliminating. Use a very small amount of paint thinners or carb cleaner (carefully) and a small wire brush to ensure that where the spark plug seats itself has a good electrical connection. I say carefully as you don't want thinners getting into the cylinder and contaminating the oil, or small metal particles ending up in the cyl. Good luck fella - we're rooting for you!

Don’t laugh at me but I always found extra virgin olive oil has brought back plastics!!! Probably zero uv protection, but if you want to bring a faded black bit of vinyl to life, it just works! :p

I’m assuming your other plugs are from the same bank of three - so it seems to me that no.4 is not getting enough spark / electrical energy. Is it safe to assume they are all gapped the same?

Excellent! So now you know it’s not a head / seal issue!

And if anyone is selling one, then I’m up for one!!

Are you sure that is not just carbon on this plug? As if running too rich or not having enough spark? Here are two of mine for comparison from the old engine that used to drink 1L of oil every 500 miles. That engine was definitely burning oil. Now see the difference to yours: you can see they are shiny and have solid deposits on them. Yours from the photo, looks matt and dry as if it’s carbon. By all means go take the head off to put your mind at rest but I genuinely think you have another issue here. If you are still convinced it’s the seals then do what has been suggested first - namely replace the seals WITHOUT removing the head.

Thanks dude. Strangely some things have changed immediately like import duties but others haven’t yet like GDPR! Ps. We are still part of Europe (as in the continent) but no longer in the European Union! :p

Sadly it tells me because I’m based in Europe, I’m not allowed to see it due to GDPR! :( Any chance of a copy paste of that listing onto this thread? I agree with Mr[mention=22019]Patcon[/mention], I too thought: 1. It’s ridiculously cheap and can’t be real, 2. Why does a wife want the garage back! It may sound sexist but it was the voice of experience speaking in my head, knowing how few wives I know want to go into the garage!!!

I find with lack of sleep my speech starts to go, it makes me more Dutch! :p I really don’t know if they ever came or LHD or not, but I know a couple of gents here that would know for sure.

I recently downloaded these while on a random parts search mission on Google - hope they are useful ...

You may have seen my post on the other thread with my homemade Mount - I too can get that thud if pressing on hard and changing up at peak torque. The issue as far as I can see is simply that the mount / arrester is storing the energy and giving it back to the diff when you come off the power. This causes the diff mount insulator to connect with itself. Top part joined to the diff connects with the bottom part joined to the cross member. I haven’t made a permanent fix for it yet, but I found that adding a bit of rubber between the diff mount insulator’s top and bottom parts makes it stop! I will probably modify a compression rod bush for this duty as they too are designed to take a lot of squashing!! If you had to use a jack to squash it, then I would be pretty sure that is your problem! Imho you definitely need a gap between the snubber and the diff.

And no, it’s “ridiculous” :p

Don’t ask why, but it reminded me of this!!!! :p

Yes sir - if I did it again I’d probably go for a 3mm gap below it. The diff will always have some lift at highway speed but not enough to stress the diff Mount insulator. The red bush / stop is really very solid, so it will transmit a fair bit of noise. Under acceleration, the diff will try to lift more but you won’t hear it as much over the exhaust / engine note.

Thanks dude. It was a really easy thing to make in the end. As for spellings: helping my kids with their school spellings I hadn’t realised how 90% of English words aren’t written anything like they are spoken!!! I realise this as my eldest writes them with perfect logic based on how they are spoken!!! :D

ROFLMAO!!! We are having internet issues with Virgin today so strange things are happening here. I was editing it to correct spellings and add the bit about the diff arrester. Hidden it now. It's Ali - as in Prince Aliiiiiiii, handsome is heeeee, Ali of Abwa!

I did indeed use the original everything. In the end I went over FSM torque with some thread-lock + a fine paint brush of yellow acrylic paint to mark the final position of the nuts / bolts. That way, I could identify if anything had moved and so far, with some serious hooligan antics, so good. I also ditched the stock nuts at the diff end of the half shafts and went for serrated flange nuts - which again haven't moved, yet!! 😉 On diff arrester, I made my own in the end as the RT mount was way too expensive (£120) by the time you did the crappy GBP: USD exchange / postage and import duties. Total cost on mine ended up about £20 I think. https://zclub.net/community/index.php?threads/the-“ak”-mount.27293/ The thread needs updating as the final version was much wider and I gave up trying to use the strap brackets. there is a 1mm gap under the red bush and a 3mm rubber washer between it and the mount to reduce vibrations.

.... and if you know anything about 5G technology, it’s a mesh network that needs lots of nodes to work effectively! So you’re doing your bit! Jokes aside, very well said Captain!! I am all for personal choice and people deciding what is best for them, but on C19 there is simply just one choice, where to go to get your vaccine. Any choice to not do it is a purely selfish / anti-social one IMHO. The truth is, this virus doesn’t care for your wealth, politics, race, social status or sexual preference. Being in Financial Services, I have way too many wealthy conservative American friends who think it’s a political thing and so what if a few people die for the sake of the economy. Honestly, I am truly aghast when I see highly educated intelligent people speak in these terms. We need to count ourselves lucky we even have the option to have a vaccine - imagine living in India where there simply aren’t enough vaccines!? Or in Iran where there are vaccines but only 1 million out of 80million have access to it.

Excellent! Well done you - now you are flying with instruments! 18.9 is obscenely lean! Ideally I would aim closer to 14.7 for idle if possible as a 16 idle is a hot one. It explains why lifting the carb piston would make it stall as there would be too much air for the fuel going in. Rule of thumb: 12-13 for power at WOT (racers like it as low as 11.5 for cooling effects) 14-15 idle 15-17 cruise 17+ on the overrun (foot off the throttle going downhill at speed, with lovely popcorn making noises in your exhaust system!) Obviously every engine set up will be slightly different around these numbers but they will all be within the quoted ranges. Here’s a table to help — Your other limiting factor is that unlike EFi, your carbs will always have a compromise somewhere. For example, on mine I have a richer idle than I like (mid 13s) but it’s perfect for cruise / wot. That is, until I get my own design custom needles CNC-ed of course! I have a needle profile that I came up with to match my engine’s characteristics - based on HOURS of experimentation and AFR data analysis. I’m telling’ ya’ brah, swear to gwad, you just ruined your life hooking one of those up!!!!!!

Totally agree, I was about to point out the same! Did I mistype it as Burfen? It is supposed to be BurLen. Yes it's the same logos and packaging as the items I buy from Burlen, being shown on the round-top website. They are basically the people who own the licence for SU carbs and manufacture them here. I didn't look closely enough at the roundtop website initially as I was on my phone, but yes, they appear to be the same HS6 and HIF carbs as go on British classics but with minor modifications. Quite a few people here have ditched the Hitachis for original HS6s as we can get parts for them here.

The OP pointed out that the site specifies made in the UK, which for obvious reasons is the Mecca of all things SU. Hence why I assume this is a Burlen initiated thing, being rebranded for the US market. Also in my 10 years of Z ownership I’ve only just seen this round tops site (the current one was set up in March 2018) but the Burlen 240z conversion carbs have been around longer than my time on the Z scene. I wonder if it was created in the UK for exactly the reasons you describe? We don’t have a ZTherapy here or access to the vast catalogue of new or secondhand parts in the US for the S30 range. From what I can see, they are basically standard HS6 SU carbs with metric hole sizes and SM needles - not a remake of the Hitachi SUs. Do you see anything that suggests otherwise? On another note, a relatively common place conversion in the UK is to HS8 carbs. Those who have done it, reported improved torque - but you do have to open out the intake manifold to receive them.