Brian-Northampton Posted June 14, 2010 Report Share Posted June 14, 2010 All, I've known that there has been a small problem with the SUs since I got her. Simply because when warm she will idle at 1000 RPM, but if I pull back on the accelerator, she'll drop to 800 RPM. At first I thought this would be an incorrectly seated throttle butterfly (met that one before) but after poking and prodding, the reason is that the rear carb throttle return spring is under absolutely NO TENSION when the car is at low revs. Therefore the rear carb throttle butterfly does not properly close. Pulling on the accelerator helps to force things shut a bit more! Here are a few pics I've managed to get of the engine bay. I suspect that this is the original "Stromberg" manifold - can anyone confirm this and got a picture of the "right" one and what the difference is?? Here you can see the front carb spring located on the bracket - nicely positioned and vertical Here similarly you can see the rear carb spring located on the bracket - at quite an angle to the carb. ?? Is it meant to be at such an angle? I suspect probably since otherwise it would probably foul the horizontal accelerator rod. You can also see that there is quite a marked difference in height between the two springs where they are anchored to the bracket. The left (rear) one being higher than the right (front) one. Slightly different shot.... And some more leaning over the engine looking down the back..... Notice the bracket that looks like it's been "doctored" to allow passage of the accelerator rod. I've got plenty of receipts that show that one of the previous owners went to reasonable pains to convert this car, loads of parts from our usual suppliers and a fortune with Burlen, but I think that the throttle bracket is incorrect (although I have the receipt for the part from one of our very famous suppliers). Can anyone tell me: Is the throttle bracket incorrect - do you have a photo of the correct bracket? Any reason why I shouldn't "adapt" the bracket (drill another hole) to bring the spring under tension Any other comment. Cheers, Brian. Quote Link to post Share on other sites
badshead Posted June 14, 2010 Report Share Posted June 14, 2010 Hi Brian Looks a bit different to my set-up which I assume is original. Quote Link to post Share on other sites
Brian-Northampton Posted June 14, 2010 Author Report Share Posted June 14, 2010 Many thanks Bill! I suspect yours is original - we can see the AUD209R label on the rear carb fuel chamber which is a bit of a give away. I have no such labels. I know that my carbs didn't originally come from a TR, I think they were another member of the Triumph family, and then correct parts added to bring them into line. Your bracket and spring layout does look much much better, and different springs.....which is interesting, because I have a receipt for the springs and they're not like yours... More investigation I think, then a decision to either get the right bracket, or fabricate something to put the spring under more tension. Anyone out there recognise the parts that I've got? Cheers, Brian. Quote Link to post Share on other sites
graeme Posted June 14, 2010 Report Share Posted June 14, 2010 (edited) Brian, My 4A is exactly the same as Bill's setup which I believe to be original. I don't recognise your bracketry at all. Cheers Graeme Edited June 14, 2010 by graeme Quote Link to post Share on other sites
Ade-TR4 Posted June 15, 2010 Report Share Posted June 15, 2010 (edited) Hi Brian, You need to block off the 2 short 45-degree pipes just in front of the dash-pots. They're later carbs and the angled pipes are part of a breather system that the TR4 doesn't employ (Dolly Sprints etc used them). The earlier HS6s don't have that arrangement, without blanking off the pipes, you'll be pulling in loads of air. Stick a bolt in the end of the pipe. Cheers Adey PS: I know Revington's stock the full linkage assembly as that's where I got mine from; It's identical to Bill's Edited June 15, 2010 by Ade-TR4 Quote Link to post Share on other sites
Brian-Northampton Posted June 15, 2010 Author Report Share Posted June 15, 2010 Thanks Adey, The pipes are already blanked off - just can't see from the photo! I'll try to ring the previous owner that did the conversion and see why he went down this route ....... can't imagine a bracket like that being in short supply, but then these things do happen occassionally. Cheers, Bri. Quote Link to post Share on other sites
Brian-Northampton Posted June 15, 2010 Author Report Share Posted June 15, 2010 Just spoke to the chap who did the SU conversion back in 2002, and he says that he had some trouble getting some of the parts, and that bracket was the closest that he could find at the time. So it looks like there was a rush on HS conversions about that time and some parts became scarce. Thanks for all you help again chaps, and for your photos Bill. I'm off to surf the suppliers websites and buy a bracket! Cheers, Brian. Quote Link to post Share on other sites
david ferry Posted June 16, 2010 Report Share Posted June 16, 2010 Brian, This should help you Complete reconditioned linkage for sale It's got nothing to do with me but I just found it for sale by Tony Sheach who you may know as TR4 Tony and also the technical expert for the TR4. Good luck Regards Quote Link to post Share on other sites
Alec Pringle Posted June 16, 2010 Report Share Posted June 16, 2010 I hadn't realised the linkages were in such short supply - this explains why back in the winter the Forum member to whom I gave a new set of linkage and all the gubbins insisted on proffering a good single malt rather than the bottle of Grouse that I'd suggested !!! Cheers, Alec Quote Link to post Share on other sites
RAHTR4 Posted June 16, 2010 Report Share Posted June 16, 2010 Brian, I see that Moss do list most of the parts you require - Page 45, illustration part numbers 78, 79, 80, 81, 82 & 84 all of which come to a grand total of £37.82. For some reason Moss do not supply the connecting shaft between the carbs - illustration part number 63 - however the item you currently have fitted looks OK to me. Regarding you other request for Triumph information on the SU HS6's, I have an original TR4A Owners Handbook printed in 1966 which has a four page supplement for those particular carbs. If of interest, send me your e-mail in a PM and I will forward a PDF copy. Regards, Richard Quote Link to post Share on other sites
Brian-Northampton Posted June 16, 2010 Author Report Share Posted June 16, 2010 Cheers Richard, I've been in touch with Moss this morning and ordered the bracket (part number 84 - 218410) which was surprisingly half the price of revingtons. I don't need the other parts - the bell crank and fittings, the one's that I have are the correct ones, I've got the Moss receipt from 2002 when these were bought, it was just the bracket that he couldn't get at that time. PM sent for the scanned PDF Cheers, Brian. Quote Link to post Share on other sites
Tr4Tony Posted June 16, 2010 Report Share Posted June 16, 2010 Brian Check the dimensions of the whole thing when you have it set up - if misaligned the linkage has a nasty habit of jamming open, which means it foot hard down time. If you want me to measure up the one I have let me know - youre also welcome to borrow if if it helps you out ! Im on cabled twin webers on everything now, so i won't use it. Regards Tony Quote Link to post Share on other sites
Brian-Northampton Posted June 17, 2010 Author Report Share Posted June 17, 2010 Check the dimensions of the whole thing when you have it set up - if misaligned the linkage has a nasty habit of jamming open, which means it foot hard down time Thanks for that bit of advice Tony (and the offer of a loan), Now you say it, I can imagine how this can happen, so I'll do the checks. Cheers, Bri. Quote Link to post Share on other sites
Brian-Northampton Posted June 17, 2010 Author Report Share Posted June 17, 2010 Package arrived from Moss today Exactly the same bracket that I've got today Can you believe it! What utter rubbish! Now I've got to send it back and try to source a real part! Feeling brassed off, Bri. Quote Link to post Share on other sites
stuart Posted June 17, 2010 Report Share Posted June 17, 2010 You could always try Burlen Fuel systems or Andrew Turner Carbs. Stuart. Quote Link to post Share on other sites
david ferry Posted June 17, 2010 Report Share Posted June 17, 2010 Brian, I'm not surprised that Moss have sent something not quite right as they will send whatever they can have made. Why not simply bite the bullet and buy Tony's. You may feel that it is expensive but in reality it isn't. It's the correct part in superb condition that you are seemingly struggling to find elsewhere. In my opinion, it's good value for money. David Quote Link to post Share on other sites
Brian-Northampton Posted June 17, 2010 Author Report Share Posted June 17, 2010 Sorry - £150 for the whole lot, when all I need is a bracket? nope, not got that much money to burn. For now, I've drilled a hole lower down in the existing bracket to at least get the spring/throttle under some tension. Not ideal, but will give me plenty of time to find the right bracket, I hope. Ho hum, all part of the joys of owning an older car. Thanks again for all your help - and thanks Richard for emailing me pics and documents. Cheers, Bri. Quote Link to post Share on other sites
TR4Geoff Posted June 17, 2010 Report Share Posted June 17, 2010 Hi Brian, I know they are not exactly local to you, but would suggest you contact Southern Carburetters at Wimbledon 020 8540 2723. They are very helpful, carry a large stock of parts and their prices are keener than those of MOSS (to whom I believe they supply spares). Geoff Quote Link to post Share on other sites
67_gt6 Posted June 17, 2010 Report Share Posted June 17, 2010 (edited) Why don't you just use stronger springs on the throttles to make sure they return properly? If that is really the problem - I have found that a bit of slop or excess length in the rods can cause the same problem. The mechanical linkage is IMO a bit imperfect anyway, compared to cables, you could find that you source all the correct gubbins and you still experience the same problems after fitting - you have to get all the connecting rods etc absolutely spot on in length to make sure that you get both fully open throttles and also throttles returning properly to their stops - I have got the correct brackets and it is still a bit of a ball ache to get it set up right. cheers Andy Edited June 17, 2010 by 67_gt6 Quote Link to post Share on other sites
Brian-Northampton Posted June 17, 2010 Author Report Share Posted June 17, 2010 I'm sure the right bracket will turn up eventually. However in the short term, I have lowered the front carb spring to a lower hole, Drilled a hole as low as I can for the rear carb and now the springs are under good tension, just a little awkward. Having done that, it is now possible to tune them. Hardly surprising with the throttle springs as they were things were out. Mixture was pretty good, but she was idling solely on the rear carb - so balance was completely out! I'm surprised she ran so smoothly - must be down to a good balancing tube ?!? Also the choke was only pulling on the front carb jet. The lost motion on the throttle shaft can now be properly set and Wow! what a difference in a responsive throttle! Woo Hoo! Now I've developed a bit of 'run on', which is common according to other threads. I'll leave alone for a while and see how it develops. Fuel is good - 95 Octane unleaded with a good glug of Tetraboost real lead additive which will also boost the Octane to 97-98 ish. Bri. Quote Link to post Share on other sites
david ferry Posted June 17, 2010 Report Share Posted June 17, 2010 Brian, Hopefully you're right that the right bracket will turn up. However, as you're finding out, they are not easy to find. Anyone who knows what they have will want at least £50 for it. David Quote Link to post Share on other sites
PILKIE Posted June 17, 2010 Report Share Posted June 17, 2010 Maybe they will give it away or sell for 50p,or a quid or 2 as they dont know! Plenty out there who dont realise that rarity has value! Whatever the part is! Its on my list of things to look out for at classic events I go to Bri,as you never know whats gonna turn up next! At least its all working well now! Quote Link to post Share on other sites
qkingston Posted May 9, 2022 Report Share Posted May 9, 2022 Recycling this topic; my question is what is the correct orientation for the SU throttle bellcrank ? I have seen pretty much every permutation in manuals and on threads various (as per pic), is there a correct one? Also my HS6s (came off a TR7 but refurbished by Andrew Turner to TR4a spec) don't have return springs fitted, there is an integral return spring on the throttle connecting rods, but I can't see anywhere on the rods or the clamps to attach a return spring, what am I missing? Many thanks David Quote Link to post Share on other sites
stuart Posted May 9, 2022 Report Share Posted May 9, 2022 (edited) Like this. Stuart. Edited May 9, 2022 by stuart Quote Link to post Share on other sites
Shielob Posted May 9, 2022 Report Share Posted May 9, 2022 Hello All, Question when it comes to the linkage back to the throttle pedal. Where the "contorted metal rod" comes out of the passenger compartment it goes through a plastic bush and is then attached to an Actuating Lever, this then joins to the Long Throttle Rod. Does your Actuating Lever (sorry cant find the correct description) sit horizontal to the ground or is it inclined at about 30 degrees? My problem is the car sits and idles ok and will accelerate gently but if I open the throttle a bit more enthusiastically the car dies. I am wondering if the arc of taken by the Actuating Lever is opening the butterflies too quickly. A bit like the lobe on a cam which gives a small amount of movement over the first few degrees then accelerates the amount of movement as it rotates. It may well be distributor timing which may also be influenced by a sudden drop in vacuum but thought I would ask the question and eliminate any complications or easy fixes first. It is a TR4 with a TR4A linkage as posted by Stuart. Thanks Edgar Quote Link to post Share on other sites
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