July 5, 201115 yr comment_537716 I think there is something wrong in the wiki on valve clearance. It says to set them cold LESS than the hot... Isn't that the wrong way around? Report
July 5, 201115 yr comment_537717 Heat = Expansion of metal components. So one would think yes. Perhaps the author should fix this, please link to the info and we will have a look. Edited July 5, 201115 yr by LittleRedSpirit Report
July 5, 201115 yr Author comment_537719 Yeah so wouldn't you want to set the cold tappets with more clearance to allow for expansion? Report
July 5, 201115 yr Author comment_537720 http://www.rollaclub.com/faq/index.php?title=Tech:Engine/K_Series/Valve_Clearances Report
July 6, 201115 yr comment_537759 Heat = Expansion of metal components. Yeah so wouldn't you want to set the cold tappets with more clearance to allow for expansion? Not necessarily - Remember that the pushrod isn't the only thing expanding. Block, head and rocker posts are also expanding, and they will probably be much hotter than the pushrod, so that's why your gap will need to be closer when cold. There's a reason the factory doesn't give you cold tappet gaps, because it's too hard. Just do it hot and get it right. Report
July 6, 201115 yr comment_537769 Looking at my notes it appears they do open up under heat, which surprises me as the hottest thing is the valve stem. Crow calls for a 16thou tappet gap, which becomes about 13thou cold. Too noisy anyway! Anyone want to check that next time they do tappets?? Read them cold then read them hot & see. Report
July 6, 201115 yr comment_537776 the cold setting would just be a ball park figure so you can start the car safely, get it up to temperature, then set them again when its hot. as an engine spends 99% of its life in the hot state, not in the cold state. so long as it doesn't close up when its cold, doesn't really matter what the gap it is, as long as its correct when its hot. which is why the gap is a bit higher for cold temps, then once its hot you set it to the proper value, the cold value just gets you close to the hot value. (that's my understanding anyway....) Edited July 6, 201115 yr by ke70dave Report
July 6, 201115 yr comment_537779 Looking at my notes it appears they do open up under heat, which surprises me as the hottest thing is the valve stem. the head would also be similar temperature to the valve stem; that's made from Aluminium, which expands at about twice the rate of steel. Report
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