Stratton Jimmer Posted January 3, 2022 Report Share Posted January 3, 2022 The GT6 was fitted with a pair of HS4 SUs by the PO. I'm enclosing two pictures of the result. Having finished the gearbox remote rebuild and the CD driveshaft mod my next task was the non-working OD which I found to be a caused by a bullet connector being open circuit. So this week I moved on to the carbs. Removing the two pancake filters which were holed, revealed that the two carbs have different jets. Only the front carb is connected to the choke cable and there is no linkage between the two. The jet on the rear carb is held in position by the fuel line as the choke arm is not connected nor is it connectable. The beast was running rather rich and I have turned the jet stops back to the weakest position possible. The front carb's choke didn't return to an off position when the choke knob was pushed home. It didn't do it when the mechanism was manually moved either. There appears to be some stiction causing the jet to stick in a slightly lowered position. A slight upward press with a finger seated it properly. The carbs have not been balanced nor the mixture adjusted accurately. Now despite all of this, the engine runs quite sweetly and motors along very well with a good throttle response. Starting isn't as good as I would like it but with choke only working on half the engine that is to be expected. I think the way forward is to change the rear carb jet to match the front, get a new set of choke linkage bits and start from scratch. The throttle cable is also an issue as it enters the fray vertically from above! Does anyone have any thoughts as to why the front jet doesn't fully rise with the choke cable slack? Link to comment Share on other sites More sharing options...
thescrapman Posted January 3, 2022 Report Share Posted January 3, 2022 I reckon the choke linkage has dropped out, as the PO did not adjust the ends correctly. Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 3, 2022 Author Report Share Posted January 3, 2022 1 hour ago, Mathew said: Is the jet gummed up or bent? Thought hs6 would be better , for higher revs. But if it runs well don't fix whats not broken! If I disconnect the choke assembly, the jet moves up and down quite freely. It seems to have been modified while the rear carb's jet is an original. Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 3, 2022 Report Share Posted January 3, 2022 the length of the jet tube is known to jam the choke return and may need a few mm trimming off the rod on the choke looks like its a nasty wax stat conversion i have seen a few they are terrible for alignment and dont operate well the geometry is all wrong looks as if its is the ball and clip set up easy for this to be wrong side of the jet lug most SU mickey mouse rods are poor mans meccano and needs a lot of orientation and work with pliers to align things you do need both chokes to be operational some have used model car UJ and rods to make a decent coupling pete Link to comment Share on other sites More sharing options...
chrishawley Posted January 3, 2022 Report Share Posted January 3, 2022 Here's some pictures of what HS4s are supposed to look like (on a Spit 1500). There should be two linkages between F and R carbs. Does that give a clue? Link to comment Share on other sites More sharing options...
Josef Posted January 3, 2022 Report Share Posted January 3, 2022 Moving the choke cable to operate on the rear carb might help a little with the sticking. That cable looks strained and I’d guess is of a length designed to operate the rear carb as that’s what the Spitfire setup is. Looking again that’s probably not a major problem, but the choke cable is bent in the photo (in the off position I assume). I prefer a solid one to a braided one as I’ve had a braided version disintegrate inside the outer and become pretty useless. I’d also say from the photos that the rear carb’s jet is currently set as if the choke was in use. The jet is not resting against the adjuster nut. Is it like that under normal operation? Link to comment Share on other sites More sharing options...
chrishawley Posted January 3, 2022 Report Share Posted January 3, 2022 Second thoughts. Can't see from you photos but are the torsion springs present and correctly fitted? Link to comment Share on other sites More sharing options...
Peter Truman Posted January 3, 2022 Report Share Posted January 3, 2022 3 hours ago, Pete Lewis said: the length of the jet tube is known to jam the choke return and may need a few mm trimming off I've just fitted rebuilt HS6 Carbs to my Dolly Sprint and the above issue mentioned by Pete was the cause of my front or RH carb choke sticking on, the thin coil spring cover jet tube was causing too much curvature causing binding I took off about a 1/8in and all OK now. I have other issues ie the new Butterfly spindles the butterfly slots are not in line with the flats that locate the idle adjustment levers, meaning the front or RH carb butterfly with no idle adjustment screw fitted won't seal ie seat in the carb body, changing the LH to RH spindles achieved the butterfly to seat and 1/16in clearance btwn the carb body throttle adjustment lug and the lever flat/seat on the front or RH carb, but the LH carb with RH spindle now had over 1/4in gap (no adjustment screws fitted)! I'm going back to SU Midel here in Sydney to discuss on Weds when they open again after Xmas Hols, there usually helpful, they have two HS6 dual carb rebuild kits CRK185 (red Jet which is what were fitted to the original carbs) @ $95, or CRK249 (black jet) @ $145, I used the CRK185 kit for the rebuild. The original worn out spindles had the butterfly slot and location flats for the idle lever in line ie same plane! Oh the issue of aftermarket quality!! If SU Midel here can't resolve I will email the UK supplier Burlin and get two new spindles, has anyone used the ebay O ring alternative spindles? Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 4, 2022 Author Report Share Posted January 4, 2022 Thanks everyone for your responses. I will reply in more detail later as the boss has chores for me this morning. Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 4, 2022 Report Share Posted January 4, 2022 good luck sorry all the snags with SU operation has given me over the years has given me an avid hate of them then i bought my 2000 which has two of them im a stromberg fan , both will do a good job but the SU linkages can be a right faf of bits and pieces there song coming on who remembers it Pete Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 4, 2022 Author Report Share Posted January 4, 2022 Dave Clark Five wasn't it Pete? Looking at the Rimmer's catalogue for the Spit, they show the attached which is what seems to have been fitted to the front carb. I think I will get a kit and fit that plus a new set of linkage for the choke and a new throttle link too as I can then reroute the throttle cable to enter the fray across the engine rather than vertically where it gets kinked by the bonnet. These jets will be right for a Spit but not for a 2.0L so that may be a problem. A pal has a Haynes manual all about SU carbs. He's going to lend it to me so I can see what they say before committing to a false purchase. Does anyone have HS4 carbs on a 2.0L engine? If so, what jets and needles are you using? Link to comment Share on other sites More sharing options...
Clive Posted January 4, 2022 Report Share Posted January 4, 2022 10 minutes ago, Stratton Jimmer said: Dave Clark Five wasn't it Pete? Looking at the Rimmer's catalogue for the Spit, they show the attached which is what seems to have been fitted to the front carb. I think I will get a kit and fit that plus a new set of linkage for the choke and a new throttle link too as I can then reroute the throttle cable to enter the fray across the engine rather than vertically where it gets kinked by the bonnet. These jets will be right for a Spit but not for a 2.0L so that may be a problem. A pal has a Haynes manual all about SU carbs. He's going to lend it to me so I can see what they say before committing to a false purchase. Does anyone have HS4 carbs on a 2.0L engine? If so, what jets and needles are you using? You need to get on the Burlen site. They make all teh SU stuff, and have te specs for every car that uses them. Ne aware that some T2000 may have a very thin airbox. That means teh airflow is very poor, so teh needles are lean (I had that issue on a 2.5 I put in my Vitesse, needed MUCH richer needles) Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 4, 2022 Author Report Share Posted January 4, 2022 Cheers Clive. Burlen here I come... Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 4, 2022 Report Share Posted January 4, 2022 31 minutes ago, Stratton Jimmer said: Does anyone have HS4 carbs on a 2.0L engine? my 2000 has HS4 and runs ABL needles but has a soft cam so its the one with a few horses missing just my luck (its a triumph thing mainly to get emissions down ) apart from finding floats being grooved by the needle( aids flooding) they have been OK for a few years now and as clive notes it has a air box similar to Vit/gt6 to me its the same thickness but the HS4 have very different hole centres and different filters to suit Pete Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 4, 2022 Author Report Share Posted January 4, 2022 My engine is allegedly a "Triumphtune" unit so should have a harder cam but without dismantling it, there's no way of being sure. The PO told me that the car was taken off the road for conversion to a race car before that project was abandoned and he got hold of it and returned it to the road. At that time it was initially painted black but the PO repainted it in Delft Blue. I know that's irrelevant to this thread but it just goes to show how important it is to have a decent history file with your car. I'm shooting in the dark really! Mind you, I would still sacrifice a little top end power for improved reliability. These carbs were fitted with K&N pancake filters which were damaged to the extent they were useless. And the car was advertised as being "VGC"! I'm just pleased that I didn't pay anything near the asking price. Burlen advertise a choke and throttle linkage kit but the HS4 version is only suitable for MGB. I wonder if the HS6 version would fit the HS4 carbs? Link to comment Share on other sites More sharing options...
NonMember Posted January 4, 2022 Report Share Posted January 4, 2022 1 hour ago, Stratton Jimmer said: Burlen advertise a choke and throttle linkage kit but the HS4 version is only suitable for MGB. I would have thought that nearly all of the choke linkage from a Spitfire 1500 would fit. The only part that's likely to be wrong is the coupling shaft between the two carbs, which is just a plain bit of 5/16" rod - 8mm fits fine and can be bought cheaply from any metal merchant or most DIY chains. Cut to length, clean up, fit. Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 4, 2022 Report Share Posted January 4, 2022 see the uj mod done on the stromberg post this week https://forum.tssc.org.uk/topic/9377-stromberg-150-cd-carb-coupling-or-linkages/ Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 4, 2022 Author Report Share Posted January 4, 2022 1 hour ago, Pete Lewis said: see the uj mod done on the stromberg post this week I did see that thanks Pete. It looks to be a very tidy job. I do have an old pair of CD150s which are intended for another project and might think about using those instead of the SUs. I can't remember where these came from but most likely from one of my brothers or from an autojumble at Stafford. I'm not even sure what they are off. Here's a couple of pics... Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 4, 2022 Report Share Posted January 4, 2022 those are Stromberg CDSE as fitted to late GT6 bit more complicated as the needle adjustment needs a allen key down the dash pot tube and the small plastic covers on the side house a temperature compensator which gives an air bleed to raise and weaken the idle mix, (best fit the manifold gaskets upside down this blocks off this unwanted emission control) any vitesse of GT6 fitted with SU run into troubkes from what i have had to deal with revert to stroms puts it back to how it should be if doing a refurb , a wrinkled diaphragm will revert to shape if washed in petrol and to set the adjustment on the needle is a small delrin washer adjust to make it level with the base of the air piston they only have choke on the front carb with a tube to the rear , ideally something better than yours show nice bit of fuel hose works ok Pete fitting these would be the way to go ( as designed ) Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 5, 2022 Author Report Share Posted January 5, 2022 Thanks Pete. I figured they were CDSE versions but never having had a car with these fitted, hadn't a clue how to go about adjusting them or connecting them up. I looked in the Haynes manual (filed under F for fiction) and it is rather ambiguous as it doesn't show a pair with all of their interconnecting pipework etc. If anyone has these fitted to their engine, I would really appreciate a few photos showing all of those interconnections. Link to comment Share on other sites More sharing options...
Peter Truman Posted January 5, 2022 Report Share Posted January 5, 2022 does this help from my 68 Mk2 Vitesse, with 150CDSE Stromberg Carbs Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 6, 2022 Author Report Share Posted January 6, 2022 Lovely photos and a great help thanks Peter. Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 6, 2022 Report Share Posted January 6, 2022 if doing a refurb do flat/face the choke valve discs and clean the metering holes on a bit of fine oiled wet and dry the temp comps have 2 0 rings to seal them and shut the adjusting nut down to close the small plunger for good if they are open you cannot set the idle mixture so far better closed or blocked off you do not want air bleed at normal temperatures Pete Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted January 17, 2022 Author Report Share Posted January 17, 2022 I removed the SUs today and found that the manifold is not correct for the Strombergs. I'm thinking that the easiest thing to do is to bring the rear SU up to the same spec as the front one, fit new linkage for the chokes and reroute the throttle cable. The PO did mention that the SUs came from a 2000 but didn't say if the manifold was also from that car. It looks like it is. The spacing of the studs on the right hand (front) are too far apart for the Stromberg while the rear (left hand) has the two alternative stud holes which are correct for Strombergs being closer than the the SU mounting holes. Here's a picture for your delectation, note that the studs are in their SU positions: Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 17, 2022 Report Share Posted January 17, 2022 the manifold on a 2000 saloon is angled to correct the tilt of the engine it wont normally be used on a upright engine i have SU HS4 on my 2000 and has just twin 2 hole faces both faces are the squared casting but both two holes only i have never seen a mix and match of the offset and square faces as you have ..........someone will recognise it 4 holes were generally HS6 a mix of 2 and 4 is to me a bit odd Link to comment Share on other sites More sharing options...
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