Ian Cooper Posted June 6, 2020 Report Share Posted June 6, 2020 Hi. I have an issue which I believe is connected to the 'cold start' mechanism on my 1970 GT6 Mk2. I've had the engine and the carbs rebuilt and last week I started her up for the first time. After a little fiddling with the timing she ran relatively well for a short time (electric fan was not connected so it was a brief run). After connecting the fan I started her up again (another brief run), and all seemed well. The following day I was looking to warm up the engine and it ran but then I noticed a lot of fuel around the cold start/overflow area so I switched off. I dried everything off, to try and determine where the fuel was coming from and attempted a restart. The engine fired, revved up and stopped. After several more of these attempts I gave up and looked around the leak area, everything was soakied with fuel and there was fuel on the floor. I called out the guy who rebuilt the carbs and he checked the floats and could find nothing wrong. We spun the engine and he said the leak was coming from the cold start mechanism. He took the carb away and 'fixed' the leak, but he said he couldn't find anything wrong, he said the fixing screws appeared too long and he shortened them to increase pressure on the seal. Carb refitted and the engine started and ran well several times (4/5) tick over was too fast (2200 rpm) and I started to adjust the screws to slow things up. Engine died and there was now fuel around the coldstart mechanism again (not as much as before) and so now I'm back to the engine firing, revving up and stopping??? Any ideas what's going on anyone?? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 6, 2020 Report Share Posted June 6, 2020 is this a cds not a cdse ?? both similar, apart from method of adjustments , there should be only choke enrichment pulled up the dip tube in the float bowl via the disc in the start valve by vacuum created within the carb throat so excess is generally from high fuel levels in the float chamber or float chamber vent being blocked by gasket etc or air filter pete Link to comment Share on other sites More sharing options...
Ian Cooper Posted June 7, 2020 Author Report Share Posted June 7, 2020 Hi Pete. Thanks for responding to my post I'm really grateful for your input. As a self confessed complete numpty when it comes to the mysteries of Stromberg carbs do you think this, apparent leak, is connected to the revving up and cutting out or would you think they are one and the same issue? In my head I can't get past the fact that the engine ran quite well so spark, petrol etc., were getting it together, and I'm reluctant to do too much buggering about without a clearer idea if I'm looking at the right thing? Thanks Ian Link to comment Share on other sites More sharing options...
Iain T Posted June 7, 2020 Report Share Posted June 7, 2020 Ian, Some photos of the carbs would be helpful. That way we can identify the carb type. Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 7, 2020 Report Share Posted June 7, 2020 Ian, so when it dies is it a slow death with wooly like running getting worse till death do us part or was it a good running with a sudden death in as much as slow rough dying sounds like excess fuelin where as a quick death is lack of fueling Pete Link to comment Share on other sites More sharing options...
Ian Cooper Posted June 7, 2020 Author Report Share Posted June 7, 2020 Hi. It's both, left to it's own devices it's a slow faltering death, if I try to blip the throttle it's pretty instant death. Link to comment Share on other sites More sharing options...
Ian Foster Posted June 7, 2020 Report Share Posted June 7, 2020 Hi Ian I have the same arrangement on my GT6 Mk2 but with 175 CD2 carbs. I think you need to try and spot exactly where the fuel is coming from, by drying off the area and then getting someone else to start the car as you stare intently at it. Is it the box, the connection to the link pipe, or the float chamber vent adjacent to it. My starter box does weep slightly and from memory is reliant on some direct metal to metal contact in the assembly. I tried to ensure flatness of a joining parts using some very fine wet and dry on a piece of glass. Your photos show the incomplete installation so a current shot might shed some further light. Ian Link to comment Share on other sites More sharing options...
Iain T Posted June 7, 2020 Report Share Posted June 7, 2020 Is the air piston orientated correctly? I know the tabs on the diaphragm should stop this from happening but.........! I believe the groves in the bottom of the piston should point towards the manifold? I think Pete identified and fixed this miss assembly on another members car. Iain Link to comment Share on other sites More sharing options...
Iain T Posted June 7, 2020 Report Share Posted June 7, 2020 As to the cold start mechanism, although I replaced mine with a new one from Burlen I still had to lap the mating surface in as it still leaked. The main leak came from the outer body to the middle as this joint by design doesn't have a gasket. Just to be sure I also used some Wellseal but be careful not to get any on the choke disc! The middle body to carb body does have a gasket. If you are going to take the choke mechanism off make sure it has two sets of graduated holes that line up with the tear shaped holes in the middle body. Hope this helps 'cos I bin there!!!!! Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 7, 2020 Report Share Posted June 7, 2020 sounds a bit like its on the rich side i would re look at float needles and float levels , is the float the right way up if it has two needle arms you can fit it upside down so the float is set but the fuel floating level is way out yes air holes in the piston must be facing engine side Pete Link to comment Share on other sites More sharing options...
daverclasper Posted June 7, 2020 Report Share Posted June 7, 2020 Something daft I did was replace the one of the air filter box to carb gasket upside down, so no air going in through that top slot. It took a few miles from cold to start misbehaving and I was probably running on three to get home. Just a thought. Dave Link to comment Share on other sites More sharing options...
Dave1360 Posted June 7, 2020 Report Share Posted June 7, 2020 None of your photos show the enrichment pipe between the two carbs. Is it actually connected now? Link to comment Share on other sites More sharing options...
Ian Cooper Posted June 7, 2020 Author Report Share Posted June 7, 2020 Hi Dave 1360. Middle pic is the complete setup as it ran, there never was an enrichment pipe between the two carbs. Link to comment Share on other sites More sharing options...
NonMember Posted June 7, 2020 Report Share Posted June 7, 2020 Without a pipe between the two, the rear carb will suck in air and run lean, while the front will spew fuel out when on choke. I suggest you put the pipe on! Link to comment Share on other sites More sharing options...
Ian Cooper Posted June 7, 2020 Author Report Share Posted June 7, 2020 Hi. This car was partly dismantled when I got it and there was no pipe between the carbs. Has anyone got a photograph of the connecting pipe? I had assumed that the two 'brass' tubes (sticking out between the carbs) were 'overflows' and was worried they would discharge onto the exhaust. The guy who refurbed the carbs didn't mention there was a 'connecting pipe missing??? Cheers Ian Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 8, 2020 Report Share Posted June 8, 2020 any bit of R9 will work the orig was a clear plastic tube just a push fit pete Link to comment Share on other sites More sharing options...
Ian Cooper Posted June 8, 2020 Author Report Share Posted June 8, 2020 This sounds like it could answer the mystery and address my worry re fuel and exhaust, I'll have a play and let you know. Cheers Ian Link to comment Share on other sites More sharing options...
Ian Foster Posted June 8, 2020 Report Share Posted June 8, 2020 Hi Ian It sounds as though we have found the problem. The pipe delivers fuel from the front to rear carb, when the starter box is operated, so the box is doing exactly what it is supposed to. I do have a new used pipe (originally supplied by Gower and Lee but too small for my 175s) which I'm happy to send you. PM me with your contact details if you are interested. Alternative any suitable piece if tube will do. Clear is helpful as you can see the fuel moving in it. Ian Link to comment Share on other sites More sharing options...
dave.vitesse Posted June 8, 2020 Report Share Posted June 8, 2020 A picture of the pipe. Dave Link to comment Share on other sites More sharing options...
Ian Cooper Posted June 8, 2020 Author Report Share Posted June 8, 2020 Hi all. I'm really grateful for all your help with this, logically it would appear to answer the issues, and I'll confirm after I've had a moment to go 'play'. I may have some hose knocking around but if not I'll be in touch thanks Ian. Cheers all Ian (getting a bit Monty Python with all the Ians 😁) Link to comment Share on other sites More sharing options...
Iain T Posted June 8, 2020 Report Share Posted June 8, 2020 I'm not an Ian I'm an Iain! Reminds me of the film Sparticus, OK it's misquoted. Fingers crossed the problem is solved🤞 Link to comment Share on other sites More sharing options...
Ian Cooper Posted June 8, 2020 Author Report Share Posted June 8, 2020 Ok all. Result, nice clean start, running with just a little damp fuel on the cold start body (I'll live with that but add it to the 'snagging' list). So thank you all again. While I'm on anyone got a photograph of the Throttle return spring setup, I'm using a luggage bungy for now but it's not ideal😂. Cheers Ian Link to comment Share on other sites More sharing options...
dave.vitesse Posted June 8, 2020 Report Share Posted June 8, 2020 It fits from the throttle cable arm to the engine side screen with an extending wire. It hooks around the vent louvres. Keep it away from the starter electrics in the same area. I took a different approach, see picture. Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 8, 2020 Report Share Posted June 8, 2020 bungy ........... nice and progressive link to canley's https://www.canleyclassics.com/?catalogue=triumph-gt6-mki/ii&diagram=triumph-gt6-mki/ii-acceleration-control Link to comment Share on other sites More sharing options...
Peter Truman Posted June 8, 2020 Report Share Posted June 8, 2020 My Mk2 has what is like a coat hanger wire that hooks onto that spring then goes between the starter and sump with a bend in it to get round the starter it's around 150mmm long, it then hooks over the lip of the sump. Its always been like that for the 50 years I've had the car, crude but it works and relatively simple to hook and unhook can provide a photo tomorrow if needed too cold (3C) and late tonight. Peter T Link to comment Share on other sites More sharing options...
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