Zed devil Posted October 14, 2013 Share Posted October 14, 2013 Hey, I've been reading a few guides online for replacing spark plugs and they vary slightly. Most guides are saying you need a 14mm spark plug socket but others are saying 16mm. The iridium spark plugs I bought to replace mine with, fit a 10mm spark plug socket perfect :S Does anyone know the correct size socket required to remove the spark plugs? Do aftermarket spark plugs (NGK) require a different sized socket? I've done spark plugs before on previous vehicles and I just tightened them so they were tight but not over the top tight. I know your meant to use the correct torque but I never had a problem. Does everyone on the forum use the correct torque or just use the method I've previously used? Also, does the UK and JDM 350z have the same spark plugs? Thanks Quote Link to comment Share on other sites More sharing options...
Jp606 Posted October 14, 2013 Share Posted October 14, 2013 (edited) Which Z? The HR uses 14mm, the DE is a different size but not sure what. ALWAYS torque spark plugs.. From NGK themselves: Torque is one of the most critical aspects of spark plug installation. Torque directly affects the spark plugs' ability to transfer heat out of the combustion chamber. A spark plug that is under-torqued will not be fully seated on the cylinder head, hence heat transfer will be slowed. This will tend to elevate combustion chamber temperatures to unsafe levels, and pre-ignition and detonation will usually follow. Serious engine damage is not far behind. An over-torqued spark plug can suffer from severe stress to the Metal Shell which in turn can distort the spark plug's inner gas seals or even cause a hairline fracture to the spark plug's insulator...in either case, heat transfer can again be slowed and the above mentioned conditions can occur. The spark plug holes must always be cleaned prior to installation, otherwise you may be torquing against dirt or debris and the spark plug may actually end up under-torqued, even though your torque wrench says otherwise. Of course, you should only install spark plugs in a cool engine, because metal expands when its hot and installation may prove difficult. Edited October 14, 2013 by Jp606 2 Quote Link to comment Share on other sites More sharing options...
Dblock Posted October 15, 2013 Share Posted October 15, 2013 Which Z? The HR uses 14mm, the DE is a different size but not sure what. ALWAYS torque spark plugs.. From NGK themselves: Torque is one of the most critical aspects of spark plug installation. Torque directly affects the spark plugs' ability to transfer heat out of the combustion chamber. A spark plug that is under-torqued will not be fully seated on the cylinder head, hence heat transfer will be slowed. This will tend to elevate combustion chamber temperatures to unsafe levels, and pre-ignition and detonation will usually follow. Serious engine damage is not far behind. An over-torqued spark plug can suffer from severe stress to the Metal Shell which in turn can distort the spark plug's inner gas seals or even cause a hairline fracture to the spark plug's insulator...in either case, heat transfer can again be slowed and the above mentioned conditions can occur. The spark plug holes must always be cleaned prior to installation, otherwise you may be torquing against dirt or debris and the spark plug may actually end up under-torqued, even though your torque wrench says otherwise. Of course, you should only install spark plugs in a cool engine, because metal expands when its hot and installation may prove difficult. Good post! Quote Link to comment Share on other sites More sharing options...
AK350Z Posted October 15, 2013 Share Posted October 15, 2013 it's probably just the difference between the plug thread size i.e. M14, and the width across the flats of your hex socket - 10mm. Quote Link to comment Share on other sites More sharing options...
Vlad Posted October 15, 2013 Share Posted October 15, 2013 im pretty sure DE is 16mm, done mine last month 1 Quote Link to comment Share on other sites More sharing options...
Zed devil Posted October 15, 2013 Author Share Posted October 15, 2013 Will have to buy a 14 and 16 beforehand just incase Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 15, 2013 Share Posted October 15, 2013 DE plug thread is 14mm the drive nut is 16mm socket, LOL! never once used a torque wrench to install a plug in my 40 odd years of building/maintaining and tuning engines, its common sense really, if you cant install a plug correctly you really shouldn't be plying with engines. Quote Link to comment Share on other sites More sharing options...
Zed devil Posted October 15, 2013 Author Share Posted October 15, 2013 (edited) Thanks for the info. I've never used a torque wrench either. Thin walled 16mm socket or 16 spark plug socket then. The NGK plugs I bought fit my 10mm spark plug socket. I've looked on Halfords website and they only go up to 14mm spark plug socket. http://www.halfords.com/webapp/wcs/stores/servlet/ProductMobileDisplay?catalogId=10151&storeId=10001&productId=170586&categoryId=255216&langId=-1 Edited October 15, 2013 by Zed devil Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 15, 2013 Share Posted October 15, 2013 That's odd most modern engines take a 14mm (thread) 16mm drive socket plug, never seen of one that uses a 10mm socket on a car engine, 10mm is tiny! Quote Link to comment Share on other sites More sharing options...
Zed devil Posted October 15, 2013 Author Share Posted October 15, 2013 Yeah, the socket definitely says 10mm on the side but it's not the size of a normal 10mm socket? Bought it from Halfords and it is a spark plug socket not a normal socket. The NGK plugs are definitely the correct ones and it fits like a glove :S Quote Link to comment Share on other sites More sharing options...
sam350z2013 Posted October 15, 2013 Share Posted October 15, 2013 Anyone use some cooper grease on the thread of the plugs ? Quote Link to comment Share on other sites More sharing options...
rabbitstew Posted October 15, 2013 Share Posted October 15, 2013 Anyone use some cooper grease on the thread of the plugs ? Nope, never done that before, and likewise, never used a torque wrench. I have however used lock-tite, superglue, evo stick & JB weld on a spark plug on my 5 turbo once in an attempt to make it stay in after a previous owner wrung the threads off through over tightening it. Needless to say, none of them worked, so it was a head off & helicoil job. Still, whilst the head, turbo, manifolds & carb were all off I had them all gasflowed on the bench and got nearly 20% better flow from them. Quote Link to comment Share on other sites More sharing options...
Dblock Posted October 15, 2013 Share Posted October 15, 2013 Anyone use some cooper grease on the thread of the plugs ? Alof of people say you shouldnt for various reasons. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 15, 2013 Share Posted October 15, 2013 I use a drop of engine oil or copper grease if the plug has proved a bit difficult to remove. Quote Link to comment Share on other sites More sharing options...
sam350z2013 Posted October 16, 2013 Share Posted October 16, 2013 Could the grease form some sort of damage to the plugs/engine in worst case scenario? 😯 Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 16, 2013 Share Posted October 16, 2013 (edited) Could the grease form some sort of damage to the plugs/engine in worst case scenario? �� Not really, worst case scenario is that plugs are not removed for considerable millage and the oil or grease hardens and makes plug difficult to remove, what usually happens though is that plugs are fitted and left, and due to combustion pressures carbon is built up in the actual first few threads and makes removal difficult and can sometimes cause the alloy part of the thread in the head to strip. Personally I would rather have some grease or oil acting as a block to carbon formation. Edited October 16, 2013 by Tricky-Ricky Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.