Jules TR6 Posted October 5, 2023 Report Share Posted October 5, 2023 (edited) I searched this site but nothing popped up within the first few pages of results, so asking here... TR6, NGK 14mm thread spark plugs (with the usual flat gasket / crush washers), recommended torque wrench setting : 18-25.3 lb.ft. (or 216 - 303.6 Ib.inch). Ok, my 3/8" wrench is in Ib.inch (and not that long, 11"), I set it to 240 Ib.inch (20 lb.ft). As everyone is saying 'don't overtighten!', I'm super cautious , finger tight, then turn with the wrench 1/2 turn extra, a bit more to 2/3 turn, 20 lb.ft seems to come in further still, maybe a whole turn ...at which point I can feel the crush washer depress, then tightness is fast. I read that for the plug to correctly dissipate heat the crush washer must be flattened, but that feels like quite a lot of force, not light pressure, not strong pressure, on the wrench, but nevertheless some force to get to the scary 'crush washer' stage. I actually felt that 15 lb.ft (180 Ib.inch) was enough for 'me', and was 2/3rd of a turn extra from finger tight, but the 'crush washer feel' was a long way away. Do I need to crush the crush washer?, which does feel like it need quite some scary pull on a 11" long wrench. Do you always pull hard enough on a wrench (torque wrench or not) to crush your crush washer spark plugs?! Edited October 5, 2023 by Jules TR6 Quote Link to post Share on other sites
RobH Posted October 5, 2023 Report Share Posted October 5, 2023 24 minutes ago, Jules TR6 said: I read that for the plug to correctly dissipate heat the crush washer must be flattened Once the washer is crushed, it stays crushed so you won't feel it yield again after the first use. Just use the lowest recommended torque. Quote Link to post Share on other sites
Bfg Posted October 5, 2023 Report Share Posted October 5, 2023 I pinch tighten new plugs to just start crushing the washer and no more. I've not measured it but I'd be surprised if they were more that 10 ft.lb. and yet they seal well and don't unscrew in use. As the plugs are repeatedly removed and refitted over the months and years, as Rob says, the washer is crushed and stays crushed, so each time I guess I'm tightening them just a little more ..until after four or five times the washer is mostlt flattened and so I tighten it more to seal. I've never noticed the plug overheating because it's not been screwed in tighter, nor do I notice blowby of gases. I do however use coppaslip on those threads and that would reduce any torque setting recorded (for the same factor of crushing). Pete Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 5, 2023 Report Share Posted October 5, 2023 You used to be able to buy the crush washers as a spare part. Probably still can. Quote Link to post Share on other sites
iani Posted October 6, 2023 Report Share Posted October 6, 2023 10 hours ago, BlueTR3A-5EKT said: You used to be able to buy the crush washers as a spare part. Probably still can. https://www.gsparkplug.com/10x-spark-plug-steel-crushable-washers-14mm.html?gclid=EAIaIQobChMIzrGkjYLhgQMVw_ntCh3plAyEEAQYAyABEgKx5PD_BwE cheap as.. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 6, 2023 Report Share Posted October 6, 2023 22 minutes ago, iani said: https://www.gsparkplug.com/10x-spark-plug-steel-crushable-washers-14mm.html?gclid=EAIaIQobChMIzrGkjYLhgQMVw_ntCh3plAyEEAQYAyABEgKx5PD_BwE cheap as.. Thanks for the link. Quote Link to post Share on other sites
Colin Symonds Posted October 6, 2023 Report Share Posted October 6, 2023 Yes I have a a couple of packs of the washers from Green Spark on the shelf and use a new one every time I take a plug out. Green Spark also have them on eBay. Quote Link to post Share on other sites
Ralph Whitaker Posted October 9, 2023 Report Share Posted October 9, 2023 I remember being told that if it was a new plug, screw in until the washer makes contact with the head, then a further half turn was enough. If re fitting a used plug make contact and then just a further quarter turn. Used that method for 50 years and never stripped a thread nor had a plug come loose. Ralph Quote Link to post Share on other sites
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