RobH

Yes, as far as I can tell it's straight. I suppose as long as the base timing is correct it's not too big an issue, it is bugging me a bit though :-\ . It's also adjusted close to the limit in a clockwise direction, as I understand it it should be more or less central to the range of adjustment. The cams are non standard so I'm wondering if that may be something to do with it... Cheers H

Out of interest, I've tried another CAS with the same result, set the timing accurately and by the time the bolts are tightened it's out by 2 or more degrees again. I've adjusted so that by the time the bolts are tight it will be 15 degree precisely but can't help feeling this shouldn't be necessary. Perhaps there's a slight problem somewhere behind the CAS. It does show how important it is to confirm 15 degrees after tightening everything up. H

NGK are the only manufacturer who makes a plug specifically designed for our (stock) engines. Equivalents from other manufacturers do not have the shrouded portion at the end of the threaded shell and the additional projection. Noz, I'm not going to waste any more time trying to convince you that my interests are not related to sales. I haven't given a toss about sales for the last 6 years. You can get a suitable set of Iridium plugs for less money than at Specialty-Z on Fleabay uk, not listed by us - sound like a salesman?? You are obviously immovable in your opinion. I agree that copper plugs are just fine for track days etc and overall performance will not be noticably less if you're changing them regularly. For extreme tuning more strength is required and the best option is Iridium/platinum race plugs (or a surface discharge plug if you're making F1 power). I'm not sure why you're persistently avoiding the point that the ground electrode is the weak point NOT the central electrode, hence my statement that it's immaterial whether detonation or pre ignition and the thermal retention within the centre electrode is irrelevant. You've picked up on this but conveniently ignored the point. It's the ground electrode that will be the issue and potentially damaged before the centre electrode in an engine which is running incorrectly - do you agree?? If not, and I'm very, very wrong please enlighten me. Obviously I'm not saying that the difference between det and pre ign is unimportant - simply that it's not relevant to this exchange and widening the topic further would take a hijacked (sorry folks) thread to a fully fledged coup! For anybody else who's still reading this thread, the conductivity of copper is not in doubt, an Iridium plug has a copper core the same as a 'copper' plug, it's only the 2mm or so of electrode welded onto the tip which is Iridium alloy, some earlier comments related to 'copper plugs' may have been misleading in this respect. Agreed that spark plugs do not add any horsepower and I've never claimed that they do, but a worn, badly adjusted or incorrect spark plug will almost certainly reduce available power. Cheers H

Yes, I am a spark plug dealer, no I am not biased, profit margins on Iridium plugs are far less than on any other type - any more 'cheap shots'? I base my information on 10 years of experience and customer feedback, including a number of well respected tuners, engine builders and even, indirectly, the military. The only specification that copper plugs may 'win' on is the conductivity of the material of the tip of centre electrode, the price difference is an issue for some but due to longer service intervals Iridium plugs reduce the cost of ownership. If you're going to change copper plugs every 1000 or so miles then performance will not be significantly less than an Iridium plug, it may even be better for the first few miles, but once the 'edges' have been taken off the electrodes (this happens very quickly) the accuracy and strength of the spark is reduced. Of course you're entitled to your opinion Noz, as I am to mine. I'm extremely sceptical of any new products in the market, various new 'ground breaking' designs have been released in the last few years, all hype and advertising but no substance. Iridium plugs have been around long enough now to be considered as proven. Plenty of road tests, dyno runs etc are available to view online and in the motoring press archives, fabrication of results would leave the manufacturer open to prosecution and would destroy a companies reputation. I've tried all sorts of plugs in three different heat ranges in my Z over the last few years, from 'standard copper' to Iridium racing and have found very little issue with any of them. I'm certainly not Pro Iridium for any other reason than results. The difference between detonation and pre ignition is irrelevant in this context, the point is that the ground electrode will become a source of ignition way before the central electrode and it's also the ground electrode that is more likely to break off (especially if regapped).

Just a couple of notes, BCR8ES appears to be ISO standard (agreed that it's the overall upper length that is different to JIS, the metal section rather than the ceramic portion, never bothered to measure before) therefore NGK have performed a classic plug manufacturer's trick and not applied their own coding system. In other words BCR8ES is the correct size for the Z32, BCPR7ES are technically not the correct size but that doesn't mean they won't work. I'm using a JIS size race plug at the moment. There are a number of plugs which are classed as JIS standard but are actually ISO length (most notably some NGK race parts). Not disputing the figures you have quoted but Ir in it's pure form would be completely useless as an electrode material, far too brittle with poor electrical and heat conduction. That's why an Iridium alloy is used, usually Rhodium, to greatly improve strength properties, resistance to oxidation and conductivity. 'Copper' centre elctrodes are usually (but not exclusively) Copper-Nickel alloys therefore the conductivity figures you've quoted are out of context. (I'm just being a pedant) The overall picture for Iridium is of a plug that does a better all round job than a copper plug. I have to say that having sold tens of thousands of Iridium plugs over the last 10 years or so the only issues with damaged centre electrodes have been through careless gapping or incorrect installation. Almost all applications benefit in some way from using an Iridium plug if a suitable part is available. A lower spark voltage is required, this means misfire is less likely when the ignition system would otherwise be reaching its maximum capacity. The best/easiest spark is created from a sharp edge, sharp edges don't last long on electrodes so the next best thing is a fine point - hence the finer the better for ignition efficiency, Iridium alloy being the current finest option. Consider it a trade off of thermal transfer against a whole raft of benefits... Detonation issues generally (and logically) come from the ground electrode, obviously much longer than the centre electrode hence the longer heat path. Iridium plugs most often use the same ground electrode configuration as a 'standard copper' plug. Both types generally use a copper core. You'd use a shorter or less projected ground if you really wanted to avoid detonation. It does raise the question of why you'd be close enough to the det threshold for the spark plug config to make a difference though. I doubt that both NGK and Denso would have chosen Iridium alloy as their best option for racing plug centre electrodes without good reason ;) . Race plugs are deisgned so as to be as unaffected as possible by vibration and to reduce the possibility of structural damage in critical applications. Not solely designed for performance but that is a major additional consideration. Each to their own I guess. I stand by the statement that the heat range is set by the manufacturer and that's that, if the thermal transfer properties were different the manufacturer would apply a different heat range number, or rather they design their plug to have specific thermal transfer properties and number it accordingly. Take a look at your copper plugs and let me know if you still think the centre electrode is more likely to retain heat and cause det than the ground electrode. A couple of mm of Iridium alloy tip welded onto a copper core centre electrode is not going to retain significant heat relative to the ground electrode. H

I do have the gaps around the plastic 'L' pieces around the rear window, they've been like that for the last 10 years though and not been an issue until now :( perhaps it's just the sheer volume of water that's made a direct hit over the last few weeks...I'll get busy with the black silicon anyway. On the plus side a good wash doesn't seem to have damaged the rear speakers and CD stacker any harm ;) Cheers H

BKR7E is a closer match to the recommended plug for the 300ZX than BCPR7ES, 'BC' type plugs have a ceramic body 2.5mm longer than 'BK' types - shouldn't be an issue either way, but the idea is that the direct fire coils (often incorrectly called coil packs) are designed to use a plug with a specific body length. It may be worth changing your plugs - even if it's just for some cheap, temporary replacements, it's worth £20 or so to rule the plugs out as the issue. Most plugs of the correct size will work fine initially, it's only with time that they may wear badly or foul up. The heat range of the part number indicates the ability of the plug to conduct heat away from the firing end - regardless of what material and how fine the electrode is. A copper plug in an NGK '7' heat range will have the same conduction property as an Iridium plug in a '7' heat range. TBH it sounds more like a bad connector or intake air leak that's the problem. Cheers H

Hi guys. Lifted the tailgate/boot lid a few days ago, after some heavy rain, been stood for a month or so. Water flooded out and directly onto the rear speakers (and not forgetting the CD stacker in the boot!). How is it getting in?? It seems to be collecting in the plastic trim at the bottom of the rear window. I have no boot spoiler, just a skin blended on and a plastic cover in the recess that the old spoiler left behind. This cover is a little loose, wondering if there's a hole behind it or something!? Cheers H

Wrench manufacturer's drive me to distraction, they call a wrench that fits 16mm hex size 10mm (the threads of a 16mm hex size plug may be 10mm, 12mm or in our case 14mm). They call a wrench that fits a 21mm hex size 14mm (14mm thread dia). Why the heck they can't just call them 16mm or 21mm and stop confusing everybody.....!?

Znut, apologies for the late reply, been a bit tied up with other vehicles :-\ . Thanks for the offer, I may well take you up on that, out of interest my bird is from Spital (also CH63). Had the injectors cleaned and tested by injectortune, seems to be a good service if their before and after test data sheet is to be believed. All injectors were flowing under 550cc by varying degrees and now all are exactly 550cc (hmm...). Oddly it's now running leaner. I suspected an intake leak, having had upper plenum and a multitude of hoses off, but testing it shows it's pretty well air tight...back to programming the ECU via the laptop I guess, if I ever get chance :( Cheers H

I'm pretty sure the 11B has a longer shroud (extended shell at the end of the threads), to protect the insulator and centre electrode better. For higher boosting engines it's preferable to reduce the projection (take the tip away from the combustion action) and close the plug gap slightly. Shrouding it more protects it and still allows the same projection for better low speed running. 11B was never officially available in the UK AFAIK, there may still be some knocking around in the USA or from unofficial importers in the UK. H

Hmm..interesting, thanks. I guess the acid test is to replace with a known good one (as usual). Mark, under low load 'cruising' AFR is around 14.5:1, I'm reasonably happy with that. Under high load at low revs (i.e. foot down hard at 3K in 4th or 5th gear) it's staying around 13.5-14:1, I'm not happy with that at all. I'm part way through building a custom map, just trying to ensure everything else is working right before meddling with the fuel map any further. Cheers H

Hi guys. Been getting a bit of det under high load at low revs (higher gears), I know I'm running lean but just thought I'd double check the timing as well. Base timing was at 20 deg so I reset to 15 deg. By trial and error I've found that I can tighten the top and bottom bolts of the CAS without affecting the timing but tightening the middle bolt causes timing to advance by 5 deg. The CAS doesn't move at all when tightening the bolts. Not sure why this is?! Perhaps it's not on straight?? Not sure how this would be possible though considering it sits on a gear and inside the cylinder head housing. It looks straight enough. Time for a new unit?? BTW, just fitted dual LC-1 widebands and gauges (hence I know it's running lean ;)). A real PITA overall but worth the pain I think... Cheers RobH

Hi guys, as nobody bit on my post about a dual LC-1 install I'll take what info I can get ;) I need a 12V (5A max) x 2 power supply to power up when the ignition is switched on to drive the heating elements in two LC-1 wideband sensors. Where would be the easiest to tap this from? Can be in the engine bay or (I guess) the loom behind the dash. Any problems likely from connecting both sensors to the same supply? TIA for an advice.. H

Hi guys. I've been running with an LC-1 temporarily fitted to one bank for some time now. Two problems, firstly (and obviously) this only shows the status of the 3 cylinder bank that it's applied to, the other 3 cylinders could be doing something completely different. Secondly, I've got it hard wired onto the battery with an 'on-off' switch which I have to manually operate when I start up/shut down, need a nudge in the right direction to help me wire it in a bit more permanently. Back to my original question, has anyone seen or created a 'how to' for a pain free permanent install of a pair (or at least one) of these (or similar) wideband sensors? It's impossible to confidently tune a custom injection/timing map with only one sensor. I also suspect one of my injectors has gone a bit iffy, a second wideband will make diagnosis and long term monitoring far easier. Cheers RobH