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Post by wannabe on May 6, 2019 23:23:00 GMT
Quick question as per title, really! The Rod Grainger manual just mentions 'replace the bolts' (or word to that effect) but makes no mention of '... with new bolts' at any point, which I take to mean replace the original bolts back to their positions. Likewise, the workshop manual does not specify new bolts. IIRC Fords used to have 'stretch bolts' that couldn't / shouldn't be re-used, hence my uncertainty, but I'm aware those over-engineering Japanese folk probably had no truck with such built-in obscelence! Thanks in advance!  |
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Post by dadbif on May 7, 2019 7:05:15 GMT
Personal preference, but I wouldn’t bother, stretch bolts have a specific tightening sequence torque wise..
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Post by wannabe on May 7, 2019 8:59:29 GMT
Personal preference, but I wouldn’t bother, stretch bolts have a specific tightening sequence torque wise.. Thanks for the input The Rod Grainger book does specify loosening/tightening them in a sequence that 'circles', and says about loosening them off in sequence quarter of a turn each, then half a turn, then all the way out - I can't remember what it says about doing them up again but will have a check. New headbolts are about £76 a set from MX5Parts so I could do with not spending that, given how much everything else has cost, lol. |
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Post by Zed. on May 7, 2019 9:58:18 GMT
tigh tarse  have you a vernier caliper? if so measure the bolts & if they are all the same length then reuse? can measure some from a '95 1.8 that I've stripped if thats any help? Rich. |
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Post by wannabe on May 7, 2019 11:27:42 GMT
tigh tarse have you a vernier caliper? if so measure the bolts & if they are all the same length then reuse? can measure some from a '95 1.8 that I've stripped if thats any help? Rich. lol This has cost me enough in parts and tools already! I'd rather not do it all again, though, so £76 is money well spent if it prevents any issues... Thank you for the kind offer! I don't have any measuring calipers but I'll try to line them up and assess them by eye - not that it will be any use if they are only out a fraction of a inch, of course  lol |
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Post by dadbif on May 7, 2019 15:02:49 GMT
I’ve never stripped or broken a cylinder head bolt, but would ALWAYS replace stretch bolts, all bolts stretch when tightened, but some are designed for single use.
I don’t think Mazda head bolts fall into the latter category..
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Post by niklas on May 7, 2019 16:18:20 GMT
I kind of like the arp ones. Makes installing everything nicer. And they are reusable for sure.
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Post by dadbif on May 7, 2019 21:15:31 GMT
ARP are excellent, I always use them on big end caps when uprating an engine.
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Post by wannabe on May 8, 2019 17:19:09 GMT
Thanks for the replies, gents I see that the ARP headbolts are 'stud bolts' (with studs and then washers and nuts) rather than 'usual bolts' (where it's all one unit): www.maruhamotors.co.jp/miata/parts/arpbolt.htmlI'm guessing it won't create any issues?? I think the main thing that confuses me is that both ends must have the same thread angle/pitch, won't they? So how can one undo them and get them out of the block again if undoing them will just release the nut and washer on the top??! I am struggling to visualise it and it's making my head hurt lol |
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Post by niklas on May 8, 2019 20:30:09 GMT
As all studs, double nut. Or use the allen fitting on the stud  Oh, they stay installed in the block when removing / installing the head, in case you thought otherwise I think i have some pictures of it in my build thread. |
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lol
le sigh