Richardtr3a Posted October 24, 2017 Report Share Posted October 24, 2017 My newly overhauled carbs have a problem. The front one is leaking from the jet. Has anyone found some modern seals, Viton ?, which would work better than the oil soaked cork. I have sorted out the bolt fixing the float chamber to the carb body, but i would like a long term to petrol leaks. I am hoping that there are o rings out there that will work. Please help if possible. Richard & H. Quote Link to post Share on other sites
TomMull Posted October 25, 2017 Report Share Posted October 25, 2017 I used Moss 365 420 and no leaks, but I've no idea what the material is. Tom Bryant, Bath, ME has Viton seals here in the US and I'm sure they won't be difficult to get in the UK. Tom Quote Link to post Share on other sites
Richardtr3a Posted October 25, 2017 Author Report Share Posted October 25, 2017 Thanks Tom I have found some at SU carbs, Burlen in Salisbury. Their man tells me that I must change the jet as well as the seals. My jets are new . I need some feedback on the Viton. There must be someone who has used them..Do they work? Thanks richard & H Quote Link to post Share on other sites
Paul Down Posted October 25, 2017 Report Share Posted October 25, 2017 Richard if you use the Forum Search facility, quite a lot of threads on SU seals etc. Quote Link to post Share on other sites
TomMull Posted October 26, 2017 Report Share Posted October 26, 2017 Thanks Tom I have found some at SU carbs, Burlen in Salisbury. Their man tells me that I must change the jet as well as the seals. My jets are new . I need some feedback on the Viton. There must be someone who has used them..Do they work? Thanks richard & H For what it's worth, I did install new jets at the same time as the Moss seals but polished them with very fine (up to 6000) wet or dry sandpaper. My new ones were far from shiny. I see no reason not to use yours with a quick polish if they don't have a blemish or mirror finish. I am no expert, however. Tom Quote Link to post Share on other sites
Fireman049 Posted October 26, 2017 Report Share Posted October 26, 2017 (edited) SU needles and jets should never wear out if they are properly centred? Tom. Edited October 26, 2017 by Fireman049 Quote Link to post Share on other sites
stuart Posted October 26, 2017 Report Share Posted October 26, 2017 SU needles and jets should never wear out if they are properly centred? Tom. I can assure you they will over time Tom Stuart. Quote Link to post Share on other sites
Fireman049 Posted October 26, 2017 Report Share Posted October 26, 2017 Hi Stuart ~ I'm sure you're perfectly right but in my experience over many thousands of miles with various SU equipped cars I've never had any problems! Tom. Quote Link to post Share on other sites
Richardtr3a Posted October 27, 2017 Author Report Share Posted October 27, 2017 I have been lucky and found some Viton o rings in Sussex. They are a commercial industrial supplier. I am planning to send my cork seals to them rather than measure it myself.. Should I send a dry seal or one soaked in oil, or both. Any advice, Thanks Richard & H. Quote Link to post Share on other sites
TomMull Posted October 27, 2017 Report Share Posted October 27, 2017 I have been lucky and found some Viton o rings in Sussex. They are a commercial industrial supplier. I am planning to send my cork seals to them rather than measure it myself.. Should I send a dry seal or one soaked in oil, or both. Any advice, Thanks Richard & H. You might find this useful, O-ring numbers are in picture caption below link: https://thosbryant.wordpress.com/2014/03/01/su-carburetor-rebuild-h-4/ Quote Link to post Share on other sites
Tom Bryant Posted October 27, 2017 Report Share Posted October 27, 2017 (edited) A few comments: 1. Viton o-rings will not work for Type H jet seals; the jets will not return well from the "choke" position. 2. Teflon o-rings (-010 size) do work well, but you need two of them in place of each cork seal, or 4 per jet, 8 per pair of carburetors. 3. For Teflon o-rings to work, the jets must be smooth, but that's rarely an issue. Sometimes the jets must be polished, but only if they were not well made to start with. 4. If Teflon o-rings are used, the holes in the sides of the jets should be chamfered to prevent damage to the o-rings as they pass over the holes. 5. In my experience, properly centered jets and needles will never wear out. 6. Type H jets can develop a leak at the bottom, where the yoke is screwed on. Loctite will fix such leaks. 7. You can buy Teflon o-rings here: http://www.theoringstore.com/index.php?main_page=product_info&cPath=367_93_96&products_id=4168 Tom Bryant Edited October 27, 2017 by Tom Bryant Quote Link to post Share on other sites
Richardtr3a Posted November 21, 2017 Author Report Share Posted November 21, 2017 After a lot of research I now have the Teflon seals and will soon be fitting them. But it has been suggested that the copper jet bearing copper washers may be a problem. Mine were new this year and I am planning to fit new ones at the week end. Do they need any preparation, annealing or polishing etc. Any advice very welcome Thanks Richard & H. Quote Link to post Share on other sites
TomMull Posted November 21, 2017 Report Share Posted November 21, 2017 I polished the jets and dulled the sharp edge on the hole. I did nothing to copper cup washers. No leaks so far, about 1000 miles. Tom Quote Link to post Share on other sites
Tom Bryant Posted November 21, 2017 Report Share Posted November 21, 2017 After a lot of research I now have the Teflon seals and will soon be fitting them. But it has been suggested that the copper jet bearing copper washers may be a problem. Mine were new this year and I am planning to fit new ones at the week end. Do they need any preparation, annealing or polishing etc. In hundreds of Type H rebuilds, I've never encountered a jet bearing washer, either upper or lower, that was a "problem." Nor have I ever seen one that needed to be replaced. Nor have I ever had to polish one. Nor have I ever annealed one, and I certainly don't recommend doing so. Tom Bryant Quote Link to post Share on other sites
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