Colin Posted July 29, 2020 Report Share Posted July 29, 2020 Hi Team ! (sorry) 😑 Working back up the line and following my recent fuel system debacle, I note that at some point (did I drop the originals somewhere??!), two of the flat headed screws seem to have turned into thin wing nutted fixings! Perfectly adequate, but I'm in a position to replace them properly now and wondered what their spec is, screws and nuts being v complicated. These days, Mthis and Mthat sizes are the norm, and I think an M5 might be close to the size but I think the thread may be not quite right!! Any ideas?? 🤔 Best, C Link to comment Share on other sites More sharing options...
NonMember Posted July 29, 2020 Report Share Posted July 29, 2020 M5 is unlikely to be any good. The original may have been a 3/16 (a.k.a. No 10) UNF or UNC (I think SUs have a few #10UNC) but might also have been Whitworth of some sort. Link to comment Share on other sites More sharing options...
Mad4classics Posted July 29, 2020 Report Share Posted July 29, 2020 Can't help with Solex; but SU float cover screws are 3/16 BSW, clamp bolts are 2BA. David Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 29, 2020 Report Share Posted July 29, 2020 Well, they shouldn't be metric, if original UK carbs from the pre-decimal days. One USA site I've just checked claims M4 is correct, but they may have been metric from the word go; I know Solex carbs for other European cars such as VW all used metric. If no-one has come up with the correct size I'll dig one out and measure over the next few days; in the meantime replacement screws are available over the water, and bound to be here too: https://www.carburetion.com/screws.asp http://www.gowerlee.dircon.co.uk/PSEItype.html Link to comment Share on other sites More sharing options...
Colin Posted July 30, 2020 Author Report Share Posted July 30, 2020 Thanks chaps. I hold a small stock of M size screws. M4 slips through, M6 is too fat. I would imagine if I got hold of M5's, the threads would not match. The 3/16 option sounds like one I should pursue via the 'net. Cheers and best, Colin W Link to comment Share on other sites More sharing options...
Badwolf Posted July 30, 2020 Report Share Posted July 30, 2020 I have found that Spalding Fasteners (via Fleabay) have an excellent stock of UNF fastenings in a variety of metals and have a good fast delivery service (user name.. spalding_fasteners) Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 30, 2020 Report Share Posted July 30, 2020 in uk metric wasnt invented in the auto industry and SU being an older design could well be older than unf i got a few from Canley last year checking some old ones they are pitch 24 dia 0.1825 which looks like whitworth !!! or 3/16"UNF apart from the dia ought to be 0.1875" both similar apart from thread angles senior moment syndrome this is for a B30 solex and im waffling SU ...Grrrr where the pills ???? Mick dolphin lists 503273 at 10P no site seem to x ref to thread sizes Pete Link to comment Share on other sites More sharing options...
Colin Posted July 30, 2020 Author Report Share Posted July 30, 2020 Thanks Badwolf. Useful information! Best, Colin Link to comment Share on other sites More sharing options...
Colin Posted July 30, 2020 Author Report Share Posted July 30, 2020 Peter, That's also good, specific info., too. Many thanks, Best, C. Just for info folks, the missing screws I replaced long ago with flat head screws and wing nuts on thr bottom. They tighten up nicely and I have never had a problem with the carb as a result! But original, they certainly are not!! The carb has a casting date stamp of 1963 on my 1970 Herald! 😁 Link to comment Share on other sites More sharing options...
Pimp my Vit Posted July 30, 2020 Report Share Posted July 30, 2020 https://www.ebay.co.uk/itm/ARIEL-SQUARE-FOUR-SOLEX-26-CARBURETTOR-SCREW-KIT-SOLEX-CARB-/303138123556 Any help... Link to comment Share on other sites More sharing options...
Colin Posted July 30, 2020 Author Report Share Posted July 30, 2020 Peter, That's also good, specific info., too. Many thanks, Best, C. Just for info folks, the missing screws I replaced long ago with flat head screws and wing nuts on thr bottom. They tighten up nicely and I have never had a problem with the carb as a result! But original, they certainly are not!! The carb has a casting date stamp of 1963 on my 1970 Herald! Pimp my Vit :- Thanks! Those outer two screws in the lower left set deffo look the part. Not sure about the other two! 😊 Link to comment Share on other sites More sharing options...
Colin Posted July 30, 2020 Author Report Share Posted July 30, 2020 Pimp my Vit :- Thanks! Those outer two screws in the lower left set deffo look the part. Not sure about the other two! 😊 Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 30, 2020 Report Share Posted July 30, 2020 but the mick dolphin correct part numbered screws are just 10p !!!!!!! pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 31, 2020 Report Share Posted July 31, 2020 I downloaded his parts list but couldn't find them.... Link to comment Share on other sites More sharing options...
Mad4classics Posted July 31, 2020 Report Share Posted July 31, 2020 The number Pete quoted is four up from bottom many pages in... Always worth droping him an email / or calling; always very helpful. Link to comment Share on other sites More sharing options...
Colin Posted July 31, 2020 Author Report Share Posted July 31, 2020 Hey Mad4 . . . ! That's really useful info., thanks ever so. Best, C. Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 31, 2020 Report Share Posted July 31, 2020 mick is goldmine of useful new old stock the shop is old school so its e mail phone etc but you can be amazed at just what he has listed you do need a triumph part number to find anything , easy as most other mainstream retailers use triumph part numbers if you dont have a parts list get one on your wish list from club shop Pete Link to comment Share on other sites More sharing options...
Colin Posted August 1, 2020 Author Report Share Posted August 1, 2020 Thanks Pete! I would imagine it'd be a question of getting a Solex part number!! Cheers though - I'll deffo be check8ng him out 😉😉 Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 1, 2020 Report Share Posted August 1, 2020 and he is ...cheaper than most .... Pete Link to comment Share on other sites More sharing options...
Morgana Posted February 14, 2023 Report Share Posted February 14, 2023 Did anyone get to the bottom of this? My Solex B30 has a couple of stripped threads and Gower and Lee suggested Helicoils. Helicoils are available in a number of Imperial threads as well as metric, so if it's possible to keep the originals it would save on head scratching later. I called Mick Dolphin today, and he has a few of the screws in stock, but is a self-confessed tyro when it comes to thread identification so can't help beyond agreeing the part number. I went through all my thread gauges and micrometer measurements of the major diameter and have not yet made a decision. The pitch is a very good match for M0.75, but the thread would then have to be M4.5 and the major diameter is almost 5mm, or about 3/16". An old Starrett gauge says 34TPI which is not a thread that exists (I wonder why they bothered to include one in the set), and while I got a reasonable result on a Whitworth gauge I haven't any of the right nuts, taps or dies to test that hypothesis. I couldn't get a good match on UNF, UNC, BA or BSF. Link to comment Share on other sites More sharing options...
Colin Posted February 15, 2023 Author Report Share Posted February 15, 2023 Hi Morgana. Confession time:- I did not contact Mick D - on the basis that (some of) the original screws seem to have stripped the thread in the carb body (must be very soft steel and I must've been over zealous in my tightenings during previous dismantling and subsequent assemblies. At the time I was out of country and inclined to use anything which would do the job (e.g. hold the two parts together tightly) and I used some bolts close to the screw size which had butterfly nuts in the stripped thread holes. These have done the job all these years! Were I to purchase a set from the part numbers given above, I'd still find I couldn't tighten in at least two of the thread, so a bit pointless. As I recall, the screws were viable still (not with mullered thread), but had clearly cleaned out the threaded body. So, what does one do . . . ? I'm sure the more capable mechanic engineers here will say cut a new thread in the lower carb body and match with a suitable screw. I'm not that au fait with such practices & have always worked round such things! Let us know how you get on!! At .10p each, a set from M Dolphin can't be a bad thing to have?? Best, C. Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 15, 2023 Report Share Posted February 15, 2023 as said earlier they certainly wont be any metric thread but far older from the days of BSF BSW vintage and pre UNF/UNC no reason why you cant drill and tap with any oversize you fancy and helicoil only works if you know what thread/pitch you want to end up with tap to a coarse M6 should work ok Link to comment Share on other sites More sharing options...
Colin Posted February 15, 2023 Author Report Share Posted February 15, 2023 Good info Pete; Addendum; My Solex, fitted to my 1970 1147 saloon, is date stamped 1963!! Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 15, 2023 Report Share Posted February 15, 2023 thats the mix and match of a classic .... classic 1 Link to comment Share on other sites More sharing options...
Morgana Posted February 16, 2023 Report Share Posted February 16, 2023 Yes, I could go to Screwfix and get an off the shelf M5 or 6 Helicoil set but since they're available in a variety of Imperial sizes then it should be possible to get a Helicoil set of the original thread and use the 'right' screws. Like you Colin, there are also a couple of holes that have odd screws and nuts on! All well and good, but getting the nuts on with all the projecting bits of the carburettor and cables is quite the fiddle, and I don't want to take the whole thing off each time I need to check the float chamber. As there's still something funny going on with the fuelling it's been on and off a number of times this week. It's a real fuss trying to do a repair and finding the fixings one takes off are metric so don't match the parts book or the spares one has to hand! Thinking out loud, if we discount metric then it's going to be 3/16" (0.1875") or gauge 12 (0.1890") - my Presto booklet is unclear about the distinction between gauges 10 and 12. Elsewhere it appears to be 10 at 0.190". 3/16" could be BSW at 24TPI; BSF at 32TPI or "special" Unified threads at 24 to 32TPI. Gauge 12 could be NC 24TPI, NF 28TPI. Gauge 10 is approximately 2BA. Also UNC/NC 24TPI; UNF/NF 32TPI, or NS 30TPI. It can be seen in the attached picture that 24TPI BSW is far too coarse. The 34TPI of the Starrett No. 6 gauge fits well. A Metric 0.75 pitch results in...33.9TPI, bringing us back to M4.5. One can see from this table of threads that there's not anything close for the required TPI and major diameter except M4.5. Alas, the major diameter is rather too large for that! BSW at 24TPI would seem to be a much better thread for alloy than the one they used, since it's significantly coarser. Link to comment Share on other sites More sharing options...
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