Smithfire67 Posted February 3 Author Report Share Posted February 3 Got the colourtune on the engine today. Ist carb tuned to blue with a wee bit of yellow no probs. 2nd carb no dice. I thought I'd have problems with that one because when I tried to wind it up level with land in the carb body it stopped moving and was about 1.5mm shof being level. Even with adjustment nut all the way up. Maybe fouling in there or something. I'll have to rebuild the lower half of the carb to get it to play ball. Could anyone point me in the right direction as to how extensive a rebuild kit I'll need? There are SU branded (genuine?) kits on the auction site for 60 quid....are these legit? Many thanks Clive Quote Link to post Share on other sites
Rod1883 Posted February 3 Report Share Posted February 3 Clive - I would again suggest/recommend having a word with Burlen in Salisbury or Southern Carbs in Crawley. I think you said you are pretty close to Crawley. I'm sure either could diagnose and recommend the parts you might need Rod Quote Link to post Share on other sites
Smithfire67 Posted February 3 Author Report Share Posted February 3 23 minutes ago, Rod1883 said: Clive - I would again suggest/recommend having a word with Burlen in Salisbury or Southern Carbs in Crawley. I think you said you are pretty close to Crawley. I'm sure either could diagnose and recommend the parts you might need Rod That is actually a bloody good idea! I really want to do the work myself and learn the carb operation instead if repeatedly shelling out. Thanks Quote Link to post Share on other sites
Ralph Whitaker Posted February 4 Report Share Posted February 4 16 hours ago, Smithfire67 said: I thought I'd have problems with that one because when I tried to wind it up level with land in the carb body it stopped moving and was about 1.5mm shof being level. Even with adjustment nut all the way up. Maybe fouling in there or something. Many thanks Clive After you wound up the adjusting nut, did you make sure that the jet was all the way up?, the choke mech could have been holding it down, or sometimes there is a wear ridge on the jet tube that stops it sliding through the cork O ring. Usually just lifting it with a finger you can feel it click up a bit. In any case I would have thought that at 1.5mm down you should still have been close to right on the mixture. Many problems on H6 carbs can be attributed to sticking choke levers and inadequate return springs, do make sure they are all going on and off correctly before diving in to dismantling the carb. Ralph Quote Link to post Share on other sites
Smithfire67 Posted February 4 Author Report Share Posted February 4 49 minutes ago, Ralph Whitaker said: After you wound up the adjusting nut, did you make sure that the jet was all the way up?, the choke mech could have been holding it down, or sometimes there is a wear ridge on the jet tube that stops it sliding through the cork O ring. Usually just lifting it with a finger you can feel it click up a bit. In any case I would have thought that at 1.5mm down you should still have been close to right on the mixture. Many problems on H6 carbs can be attributed to sticking choke levers and inadequate return springs, do make sure they are all going on and off correctly before diving in to dismantling the carb. Ralph Thanks Ralph Yes, the highest I could get the jet was about 0.5mm under the flat of the carb body. That's with winding if up with the nut and also pushing it up from below. Clive Quote Link to post Share on other sites
BlueTR3A-5EKT Posted February 4 Report Share Posted February 4 (edited) Not a daft question…..based on there being an unmatched pair of pistons and dash pots is there a chance you do not have the same needle in both carbs? They should both be SM for a standard TR and the hole in the jet that they slide into should be 0.100”. The SM will be stamped on the shank of the needle that is gripped in the piston. Simple to test for jet size. The standard SM needle should drop into the jet hole snuggly right up to its shoulder. If it goes part way it is is a .0.090”. If it is loose it is a 0.125”. There are only 3 sizes of jet orifice spin common fitment. Edited February 4 by BlueTR3A-5EKT Quote Link to post Share on other sites
Bfg Posted February 4 Report Share Posted February 4 (edited) 18 hours ago, Smithfire67 said: I thought I'd have problems with that one because when I tried to wind it up level with land in the carb body it stopped moving and was about 1.5mm short being level. Even with adjustment nut all the way up. Maybe fouling in there or something. I had this with the forward carb on Katie my TR4 Only after I disconnected the (underneath) tie-bar which operates the the choke ..at the bottom bracket on the jet - the full screw adjustment of the jet was possible. ^ Then, the end nut (nearest the forward carb) on the cross linkage to the choke was loosened, to re-adjust the position of that (underneath) tie-bar ..so its bottom screw hole aligned with that of the bracket on the jet. That done, I could adjust each of the twin carb's jets - so each of the spark-plug colours matched and the twin-carb fine balance achieved. I don't use colour tune, but instead use an air flow meter. This was achieved over several runs, but the plugs are now evenly straw in colour. Hope that helps, Pete Edited February 4 by Bfg Quote Link to post Share on other sites
Ian Vincent Posted February 4 Report Share Posted February 4 59 minutes ago, BlueTR3A-5EKT said: Not a daft question…..based on there being an unmatched pair of pistons and dash pots is there a chance you do not have the same needle in both carbs? They should both be SM for a standard TR and the hole in the jet that they slide into should be 0.100”. The SM will be stamped on the shank of the needle that is gripped in the piston. Simple to test for jet size. The standard SM needle should drop into the jet hole snuggly right up to its shoulder. If it goes part way it is is a .0.090”. If it is loose it is a 0.125”. There are only 3 sizes of jet orifice spin common fitment. I’m with Peter and thought I’d posted a reply along the same lines as his yesterday but somehow it disappeared without trace into the ether. Rgds Ian Quote Link to post Share on other sites
Smithfire67 Posted February 4 Author Report Share Posted February 4 1 hour ago, Bfg said: I had this with the forward carb on Katie my TR4 Only after I disconnected the (underneath) tie-bar which operates the the choke ..at the bottom bracket on the jet - the full screw adjustment of the jet was possible. ^ Then, the end nut (nearest the forward carb) on the cross linkage to the choke was loosened, to re-adjust the position of that (underneath) tie-bar ..so its bottom screw hole aligned with that of the bracket on the jet. That done, I could adjust each of the twin carb's jets - so each of the spark-plug colours matched and the twin-carb fine balance achieved. I don't use colour tune, but instead use an air flow meter. This was achieved over several runs, but the plugs are now evenly straw in colour. Hope that helps, Pete Thanks Pete....choke totally disengaged before hand do hopefully not a factor. Clive Quote Link to post Share on other sites
Bfg Posted February 4 Report Share Posted February 4 2 hours ago, BlueTR3A-5EKT said: Simple to test for jet size. The standard SM needle should drop into the jet hole snuggly right up to its shoulder. If it goes part way it is is a .0.090”. If it is loose it is a 0.125”. There are only 3 sizes of jet orifice spin common fitment. That's useful to learn. Thanks Peter Pete Quote Link to post Share on other sites
Smithfire67 Posted February 4 Author Report Share Posted February 4 2 hours ago, BlueTR3A-5EKT said: Not a daft question…..based on there being an unmatched pair of pistons and dash pots is there a chance you do not have the same needle in both carbs? They should both be SM for a standard TR and the hole in the jet that they slide into should be 0.100”. The SM will be stamped on the shank of the needle that is gripped in the piston. Simple to test for jet size. The standard SM needle should drop into the jet hole snuggly right up to its shoulder. If it goes part way it is is a .0.090”. If it is loose it is a 0.125”. There are only 3 sizes of jet orifice spin common fitment. I have the jet assembly out now. Both the needles are SM, and on the carb I have apart, the jet has a 0.100 hole. Some of the seals are starting to disintegrate so I'll wait till I have a service kit to replace them. Many thanks for the informative input everybody. Clive Quote Link to post Share on other sites
stuart Posted February 4 Report Share Posted February 4 To do things properly you need two of these https://sucarb.co.uk/carburettor-kits/rebuild-kits/standard-rebuild-kits/rebuild-kit-for-h6-carburettors-suitable-for-various-applications.html Stuart. Quote Link to post Share on other sites
Rod1883 Posted February 4 Report Share Posted February 4 1 hour ago, Bfg said: That's useful to learn. Thanks Peter Pete Yet another thread started by a non-member that has, through its discourse, yielded fantastic information and insights for us all. Quote Link to post Share on other sites
stuart Posted February 4 Report Share Posted February 4 34 minutes ago, Rod1883 said: Yet another thread started by a non-member that has, through its discourse, yielded fantastic information and insights for us all. Not for much longer I fear Stuart. Quote Link to post Share on other sites
Bfg Posted February 4 Report Share Posted February 4 1 hour ago, Rod1883 said: Yet another thread started by a non-member that has, through its discourse, yielded fantastic information and insights for us all. I agree. Quote Link to post Share on other sites
Smithfire67 Posted February 6 Author Report Share Posted February 6 Another update Fitted the SU superdry seals kit I received this morning. This restored the free travel of the jet all the way up. Hurrah. Took the opportunity to also refit some low mileage champion L82c I had knocking about after hearing some negative comments about plugs with an R prefix (the ones I had in the car were NGK BR6H) Fired the old girl up and after settling sounded much smoother on idling and pick up. Also balanced the carbs individually and set the idle mixture with a gunson colourtune. Not a perfect colour, but a hell of an improvement. Checked one of the plugs afterwards and the amount of soot had decreased considerably. Still room for improvement, but feel like I'm getting somewhere now. Clive Quote Link to post Share on other sites
stuart Posted February 7 Report Share Posted February 7 17 hours ago, Smithfire67 said: Another update Fitted the SU superdry seals kit I received this morning. This restored the free travel of the jet all the way up. Hurrah. Took the opportunity to also refit some low mileage champion L82c I had knocking about after hearing some negative comments about plugs with an R prefix (the ones I had in the car were NGK BR6H) Fired the old girl up and after settling sounded much smoother on idling and pick up. Also balanced the carbs individually and set the idle mixture with a gunson colourtune. Not a perfect colour, but a hell of an improvement. Checked one of the plugs afterwards and the amount of soot had decreased considerably. Still room for improvement, but feel like I'm getting somewhere now. Clive You can only really check plug colour properly by doing a "Plug chop" In other words take the car out for a good run and find a layby where you can switch engine off and coast into then check the plug colour, an idle check isnt really representative of whats happening under load. Just mind your fingers as the plugs will be hot! Stuart. Quote Link to post Share on other sites
Bfg Posted February 7 Report Share Posted February 7 35 minutes ago, stuart said: You can only really check plug colour properly by doing a "Plug chop" In other words take the car out for a good run and find a lay-by where you can switch engine off and coast into then check the plug colour, an idle check isn't really representative of what's happening under load. Just mind your fingers as the plugs will be hot! Stuart. I cannot disagree with you Stuart, regarding what a 'plug chop' is ..but I'd contest whether it is necessary to do so, to assess the colour of the plugs. My own practice is to power-wire-brush the plugs clean before driving to the club meeting (some 27 miles away for me). Of course, I then drive home after the event.. and when I arrive home - I promptly cut the engine. Fortunately the ground here is level enough to then push / roll the car into the garage. And I check the plugs the following day, or whenever. This journey is representative of my normal driving ; usual revs and engine loads. And 54 miles (some motorway and some town) is distant enough to twice warm the engine to correct working temperatures and colour the plugs. The final minutes of my journey to home, through the local suburbs, late in the evening when it's mostly clear of traffic, isn't enough to effect their colour very much at all. Cutting the engine as I soon as I arrive home, before I've opened the garage doors, and not starting her again to drive the car into the garage - likewise doesn't alter the results. No concern the following day about hot plugs and burnt fingers. Tools etc., are in the garage, so the task is quick and convenient. Spark plugs colour being even across all cylinders, and an air-flow meter to balance those carbs at (typically) three engine revs, plus when cold and needing choke, seems to work for me. I've done this, I think, four times with Katie, since I fitted these professionally refurbished carbs, with minor adjustments between each to get to where we are now. I'm not disputing you Stuart, I'm just saying that professionally you'll need to get results on the day when you're doing the job, but for most of us ..a more laid back approach to checking plug colour - is equally as good for normal road use & normal road cars. Pete p.s. I used to use a Colortune, but now don't because as you correctly say ; unless you're using it in conjunction with a rolling road, the engine is not under load and so it's not as representative. Quote Link to post Share on other sites
Smithfire67 Posted February 8 Author Report Share Posted February 8 Thanks for the responses chaps... In defence of the colour tune, yes petrol has changed pretty radically over the last 30 years, but if you know what flame colour is right with your chosen fuel and your set up, It certainly is handy, especially when setting up after a rebuild etc. Clive Quote Link to post Share on other sites
Smithfire67 Posted February 14 Author Report Share Posted February 14 Just to let you know... After rebuilding the front H6 carb jet assembly, swapping back to Champion L82c plugs, adjusting the richness and balancing the airflow, the car runs really well! But the best bit is, it's cured the mysterious stalling at junctions thing that was driving me potty! Really lovely tick over, pulls well etc. I think the timing could still do with a tweak....but that's maybe something for the rolling road guys to fine tune. Many thanks for the words of wisdom! Clive Quote Link to post Share on other sites
Hamish Posted February 15 Report Share Posted February 15 Great result and thank you for the feedback always nice to hear a success story Quote Link to post Share on other sites
Smithfire67 Posted February 15 Author Report Share Posted February 15 28 minutes ago, Hamish said: Great result and thank you for the feedback always nice to hear a success story Thanks Hamish The resistor plugs being swapped out made the most difference....something in my ignition circuit really did not like them! Clive Quote Link to post Share on other sites
Rod1883 Posted February 15 Report Share Posted February 15 That's great Clive, and as Hamish says, it's always nice to get the updates, especially when successful. When I last took the 2 out for a run about four weeks ago it wasn't running well at all -spluttery, huge dead spot when the accelerator was pressed any more than really gently - so I may well have to recheck the set up of the carbs again. I'm hoping it might have just been a combination of it being really cold and old fuel so I may well try topping up with fresh first. I was interested to read your comment about Superdry seal kits and that led me to look that up. It seems that the superdry and the original are not interchangeable - I must look at the invoice from my carb rebuilder and see what they used... Quote Link to post Share on other sites
Smithfire67 Posted February 15 Author Report Share Posted February 15 1 hour ago, Rod1883 said: That's great Clive, and as Hamish says, it's always nice to get the updates, especially when successful. When I last took the 2 out for a run about four weeks ago it wasn't running well at all -spluttery, huge dead spot when the accelerator was pressed any more than really gently - so I may well have to recheck the set up of the carbs again. I'm hoping it might have just been a combination of it being really cold and old fuel so I may well try topping up with fresh first. I was interested to read your comment about Superdry seal kits and that led me to look that up. It seems that the superdry and the original are not interchangeable - I must look at the invoice from my carb rebuilder and see what they used... That's true....but all the parts to rebuild are included. If I remember rightly it's the cup that holds the new large nitrile washer that is replaced? Pretty easy to do, but maybe on a warmer day than today! Having said that, I'm taking the 3 up Ditchling beacon this afternoon. Hood down and warm headgwear! Clive Quote Link to post Share on other sites
Rod1883 Posted February 15 Report Share Posted February 15 Where did you get your kit from Clive, and was there a part number? We've just got back from a quick run to Goodwood in the Stag to see the MG's On Track. It was a bit cold to stand around for too long, but we bumped into a few people we know and Darren in his TR4. Quote Link to post Share on other sites
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