andymcp Posted January 20 Posted January 20 Try www.minispares.com for SU carb parts. I found them much cheaper than anywhere else when attempting to dial in the HS4s on the Herald. 1 1
flatter4 Posted January 20 Posted January 20 I run HIFs on my GT6. There's a separate discussion on their advantages - but I maintain they are better than the older designs (temperature compensation on mixture being one thing....) But.... ethanol will swell the seals, and after standing they will dry out and leak. Until the new fuel swells them back up. So one leak you see is from the lower float chamber seal. Part 46 here:
flatter4 Posted January 20 Posted January 20 The other thing worth checking is the floats. For inclined carb installations (typically the V8) the float shape is different to give the right height control. Worth checking you have the right floats for horizontal installations Is the leak definitely overflow - or from the (item 46) seal?
Nick Jones Posted January 20 Author Posted January 20 Thanks. It’s definitely from the overflows. We actually fitted the extended drain pipes (because they were there) and have had literally full bore flow from those (mainly the back one) into a jar at times. These carbs were originally from a ‘79 Allegro 1500 and I ran them very successfully on my Vitesse for several years before going EFI, so definitely horizontal install. No leaks from the float chamber seals. They are new and I have some spares too. Today I’ve been advised to drop the fuel pressure still further (proper spacer block on order) and filters on the way. I was also advised that “they’ll leak until they don’t and then they’ll be fine and you’ll never be sure why”. This kind of mirrors my previous experiences with Strombergs, though I’ve never known Strombergs be this annoying!
Nick Jones Posted January 22 Author Posted January 22 Another session today. I bought a fuel pump spacer from MiniSpares (because 1/3 price of any Triumph supplier!) and we fitted that. It’s 12.5mm thick. That brought the fuel pressure down to 2 psi and initially that seemed to work. Managed to run it long enough to get warm and start to dial carbs in. Then the back carb started playing up again. Seems to be engine shake that sets it off now…. But it’s impossible to set the carbs well enough to eliminate that when it keeps flooding itself. Added one of my 1.5mm PTFE spacers back in giving about 1.6-1.8psi but no difference. Possibly it’s crud related. I did fit a filter this morning but have not had the carbs apart since. Bored with that we moved on and set the front wheel bearings for a quick, easy win. Then pulled the rear wheels off and removed the drums to find nearly new shoes and cylinders with decent looking hardware. Drums pretty good too and barely lipped. Drums refitted and young ‘un shown how to adjust them. One issue spotted though is that being a long-shaft car, it should have a short length of hard pipe on the backplate and the flexihose running to the end of that. This was present on the left, but on the right the flexihose was routed direct to the cylinder passing outside the damper and under the spring, rubbing on both. Definitely MoT fail and unsafe. Luckily my one remaining length of copper pipe was exactly (I mean EXACTLY!) the right length and necessary fittings in stock so a new pipe was made and fitted. The flexihose had survived unmarked as its one with a spring around it and the car has clearly done very few miles like this. Bled up fine. Another win. Also managed to wrestle a couple of spring buttons in between leaves 2&3. 3&4 may also be just possible in the car (getting the remains of the old ones out will be challenging), but 4&5…. No way! We’ve also improved the mounting of the Securon seat belt stalks to make them less uncomfortable/lethal. Interestingly these have switches in them to work the “fasten seat belt” light - never knew these existed. Something doesn’t work though as the light remains on whatever…. Some progress at least! If we could only sort that bloody carb!! 1
rogerguzzi Posted January 23 Posted January 23 Hello Nick I thought SU;s liked 2 to 2.5psi max so something is not right? Still working up to change Spittys clutch!!(I agree with you 5% less is nothing to worry about so the flywheel stays put!) Plus proper stuff that works if not liked now by some who worry about all sorts of things and now there is Trump who does not seem to believe in lots of things that we all do ?? Roger ps I am almost glad I am old! pps We will book a second ferry Spain tomorrow(it's only money and the kids have had Plenty of ours and the Grim reaper is getting ever closer?) pps still watched a good old film tonight and drunk a bit to much but Sod it you only live once in my book so enjoy it if you can? 1
Nick Jones Posted January 23 Author Posted January 23 8 hours ago, rogerguzzi said: I thought SU;s liked 2 to 2.5psi max so something is not right? Me too! Would just buy new floats and needle valves, but that’s £150 !!!
Escadrille Ecosse Posted January 23 Posted January 23 4 minutes ago, Nick Jones said: Me too! Would just buy new floats and needle valves, but that’s £150 !!! It all does seem to have become exorbitantly expensive
Gt64fun Posted January 23 Posted January 23 6 hours ago, Nick Jones said: Would just buy new floats and needle valves, but that’s £150 !!! Nick Presumably it is possible to check that the floats 'float' and as long as the fulcrum points and the bearing point on the needle valve is OK, they should be serviceable. I have always used Gower and Lee for Stromberg spares. Might be a bit cheaper that Burlen. Ian
egret Posted January 23 Posted January 23 SUs seem to be a great example of seemingly chaotic behavior generated by relatively straightforward components. To do disservice to an old quote: Any sufficiently complex carburetor system can be described as black magic 1
Nick Jones Posted January 23 Author Posted January 23 3 hours ago, RedRooster said: +1 on checking the floats do float. They don’t have fuel in them…..
Nick Jones Posted January 28 Author Posted January 28 Was still kicking my ass on Saturday. Tried cleaning the carbs out (there was quite a bit of crap in the back one but nothing to speak in the front) with the hope that now there’s a filter there won’t be any more. Initially seemed to work, but then the back one started spewing again just as I was getting the adjustment somewhere near At this point I remembered the last SUs in service were on Chris’s Spit (displaced by EFI) and they’re in the garage loft. Wrong size as HS2 but what are the float valves like? Oh. That’s interesting. One from the HIF on left. I fitted that in the late 90s. No idea where it came from. On the right is one that came out of the HS2 sourced from Burlen 7/8 years ago. The sprung plunger will likely help damp vibration…… And the top one from the HIF has a much bigger jet hole so will be more sensitive to fuel pressure…… Needless to say the HS2s are now without their float valves. I haven’t tested yet (it got dark on me again), but I’m hopeful….. The oddball big hole/solid shank arrangement worked just fine in the Vitesse though.
Escadrille Ecosse Posted January 29 Posted January 29 Hmm, interesting! I assume that the ones from the SUs are aluminium and will weight a fraction of the big brass ones. That and the spring damping will certainly change the system dynamics. Hopefully in a good way
Nick Jones Posted January 29 Author Posted January 29 Yes, the weight difference is a good point I’d not thought of! Hope it works - thoroughly fed up with it! Find out tomorrow.
Gt64fun Posted January 29 Posted January 29 Nick Sounds hopeful....I sure fingers are crossed all over 'sideways land'. Did you have to adjust float levels?
Nick Jones Posted January 29 Author Posted January 29 2 hours ago, Gt64fun said: Did you have to adjust float levels? Yes. I’ve got everything crossed…… 1
Nick Jones Posted January 30 Author Posted January 30 So….. ….. seems to have done the trick. No more barfing fuel. It’s not the end of the running issues though. Cannot get a decent idle. It has a marked lope, whatever I do. Possibly it has “a cam”…. Pulls well from just off idle, but soon runs out of puff, having gone lean enough to actually misfire. Pull out the choke and it takes off briskly. It’s still running the std ADN needles. At present it’s got a 4-2-1 manifold and GT6 exhaust but standard air filters/box. So I’m surprised it’s affected as it is. Perhaps another indication the cam isn’t standard. Will have to have a rummage through the needle collection. Although… it’s the original distributor, on points (good quality ones!) and , other than a few degrees of random slop, there doesn’t seem to be any mechanical advance working. Vac advance does work. Potentially this could be a contributor to it’s going flat as the revs rise. Will be investigating this! In other news Old spring button. The rest were much worse New spring buttons…. Fitted fairly easily without removing the spring (no chance of getting the top pair in though). This has lifted the rear end enough to be useful. Towbar (!) removed. Wasn’t well attached. Front suspension roughly set up. It drives nicely. Passenger door adjusted up a little so it opens and shuts easily. Easy win. Bella officially has attitude. Test drive was initially firmly rebuffed with a well stuck clutch - rusted to the flywheel. Start in gear trick failed several times. Had to jack the rear end up and batter it in gear against the brakes and eventually it let go. Brakes are rubbish. No bite. Might just need bedding in but they seem a bit too bad for that. Possibly I should not have assumed that the fresh looking calipers were ok…. Driving again is definitely a big win though!
JumpingFrog Posted January 30 Posted January 30 I would have pointed to the lack of mechanical advance as the main culprit for a lack of performance? You can also try a thicker dashpot oil if it's only going lean under acceleration, but that's an area with some very strong opinions. Modern thin engine oil (say 10W30) worked well for me, but my Dad always swore by Redex. How are you setting the mixture at idle? I've always found the piston lift test more or less useless (or I'm doing it wrong), Colour Tune usually gives good results -so long as you manage not to overheat it and get it stuck in the head (been there, done that). I strongly agree with Andrew's comments, SUs are good when they work, but getting them to work well can require a Ouija board. Hope it gives some joy soon! 1
SpitfireBGT Posted January 31 Posted January 31 Worn throttle shafts gave me a lumpy idle way back when I had SU's. Grease or heavy oil will seal it up temporarily. check the weights and springs in the distributor. Listen to me acting like I know something you don't. Without this forum I wouldn't have got my Spit running on PI. Thank You 1
egret Posted January 31 Posted January 31 If you've not discovered him then there's a chap called AC Dodd who pops up on mini forums, and had a YouTube channel. He seems extremely knowledgeable and I think I got a few pointers from his posts and videos that helped me better understand what was going on. https://youtube.com/@acdodd?si=7q-5nYLPWhi6fMO3 1
Nick Jones Posted January 31 Author Posted January 31 9 hours ago, JumpingFrog said: You can also try a thicker dashpot oil if it's only going lean under acceleration It’s at least 10/40 already…… Not an acceleration thing specifically. I think a combination of going lean and lack of advance, though adding fuel with the choke certainly woke it up. Part throttle more so, possibly because getting vac advance there! Throttle spindles seem decent. Potentially there’s still an air leak elsewhere but it seems to be possible to get both carbs too rich at idle. Going to attack the distributor and check valve clearances - top end is suspiciously quiet!!
Escadrille Ecosse Posted January 31 Posted January 31 2 hours ago, Nick Jones said: It’s at least 10/40 already…… Not an acceleration thing specifically. I think a combination of going lean and lack of advance, though adding fuel with the choke certainly woke it up. Part throttle more so, possibly because getting vac advance there! Throttle spindles seem decent. Potentially there’s still an air leak elsewhere but it seems to be possible to get both carbs too rich at idle. Going to attack the distributor and check valve clearances - top end is suspiciously quiet!! Does kind of point to mixture further up the range with lack of advance aiding and abetting. However good to see it actually running, even with a bit of 'attitude' Those spring buttons and the dog's
Nick Jones Posted January 31 Author Posted January 31 So…. Brake calipers are fine. I think it’s a bedding in think - they improving. Also bled the fronts and shifted a little air so the pedal feel is a bit better. Distributor freed off easily and is actually in reasonable condition under the grime. Swapped in ABL needles with the original red springs and set the carbs up again. This time with colour tune (thanks for the reminder David!). Got front and back evenly “just blue” at idle. Balanced again. We now have something resembling an idle but still the persistent “lope” and reluctance to stay idling at less than 900rpm. Checked the valve clearances which seem to be intentionally set at 12 thou inlet 15 thou exhaust. Not standard and not rattly either. Goes very much better though still a little lean higher up I think. Also stops better, though plenty of room for improvement. Maybe wants pads that are not made of greased weetabix…..? Mintex 1144 if can be found? Investigated the non functional sidelight and found this WTAF?!! Yes, the glass has melted….. never seen that before! Luckily the the holder and lens has escaped with only minor singeing. He’s taken it home (20 miles) and made it. The speedo has given up completely now though…. Current stance Tyres are 165/65 on 5.5”. Bit small and not helping the gearing any. OD is on the short list….. And an oil cooler. 1
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