Ian Foster Posted November 2, 2022 Report Share Posted November 2, 2022 Joe You are revving each carb separately by moving the lever on the shaft that rests on the throttle stop. When you rev the rear carb the centre part of the linkage (where the throttle cable attaches) moves, but doesn't seem to move when you rev the front one. Are the throttle spindles locked together ? Ian 1 Link to comment Share on other sites More sharing options...
gt6j Posted November 2, 2022 Author Report Share Posted November 2, 2022 (edited) Hi Ian yeah they are both disconnected its just catching the connector a bit on the rear one but both moving on their own accord. Just on air leak, I have this cork spacer gasket between the carb and manifold (not my carb pic found online) the weird shaped bit in the hole (like a finger??) pokes out from the side of the seal when everything is bolted up assume that is normal? Edited November 2, 2022 by gtjoe 2nd pic is my gasket, can sort of see small gap there Link to comment Share on other sites More sharing options...
johny Posted November 2, 2022 Report Share Posted November 2, 2022 There must be a reason for that cutout in the insulator piece and it looks like it should be matched by gaskets that have the same shape - part number 147659. If you suspect an airleak you could try spraying the joints with Easystart or something similar while the engines running to see if theres any change in revs... 1 Link to comment Share on other sites More sharing options...
NonMember Posted November 2, 2022 Report Share Posted November 2, 2022 That's the wrong spacer for that manifold. You need the one without that extra cutout. As it stands it is creating an air leak and that's almost certainly the cause of your problems. (This may suggest you have a mismatch between manifold and carbs, of course) 1 Link to comment Share on other sites More sharing options...
johny Posted November 2, 2022 Report Share Posted November 2, 2022 Dont know as it shows as being the correct insulator for all mk3 GT6 but I think has been used without the correct gaskets either side of it so will of course leak badly... 1 Link to comment Share on other sites More sharing options...
gt6j Posted November 2, 2022 Author Report Share Posted November 2, 2022 Right definitely will whip them out and take another look there, cheers again I'd be lost without this help. I'm sure when I replaced them just other day they matched the spacer (new gasket either side of spacer) but that would still sort of lead to a gap and air leak (I think). I also have gaskets without the little extra bit with the refurb kit. Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 2, 2022 Report Share Posted November 2, 2022 that cut out is the escape for the bleed air via the TC units but it must not allow any gap or air ingress if the cutout doesnt seal against the manifold flange you will get your problem Pete 1 Link to comment Share on other sites More sharing options...
NonMember Posted November 2, 2022 Report Share Posted November 2, 2022 1 hour ago, johny said: Dont know as it shows as being the correct insulator for all mk3 GT6 It is correct for Mk3 GT6 as they have the CDSE carbs with the air bleed. However, that manifold in the picture looks like a Mk2 manifold with flanges that are too small for the CDSE carbs. Unless that's a trick of the photo, in which case the correct gaskets might fix it. 1 Link to comment Share on other sites More sharing options...
johny Posted November 2, 2022 Report Share Posted November 2, 2022 Yes I can see in the photo the gaskets dont match the spacer but with a bit of luck theyre just installed upside down🤞 1 Link to comment Share on other sites More sharing options...
Ian Foster Posted November 3, 2022 Report Share Posted November 3, 2022 17 hours ago, gtjoe said: yeah they are both disconnected Joe Sounds as though there might be an issue with how the insulators are fitted. If so and if it's a case of just flipping them over, then it's a nice easy fix. The carbs need to be locked together to carry out the piston lift mixture check....and balanced as I mentioned above. If you don't have a balancer (a piece of tube will also work), then you can establish a basic set up by backing off the throttle stops (carb linkage independent) winding the screws until they just contact the stops and they screwing in by an equal number of turns on each. Tighten the linkage after. If any subsequent adjustments are need as long as you do the same on both, it should be in balance. Good luck. Ian 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 3, 2022 Report Share Posted November 3, 2022 and lifting pins /lifting the air piston this is often misguided you only lift the piston a small like 2mm and listen for a hint of idle change if it rises 50 rpm for a couple of seconds its rich if it falters 50 rpm its lean for a couple of seconds if nothing its about right if you give the piston a good prod or yank it up it will just stop the engine its a very touchy feely job , no gorilla work Pete 1 Link to comment Share on other sites More sharing options...
johny Posted November 3, 2022 Report Share Posted November 3, 2022 7 hours ago, Ian Foster said: Joe Sounds as though there might be an issue with how the insulators are fitted. If so and if it's a case of just flipping them over, then it's a nice easy fix. In the first pic the inner gasket is wrong and it looks like the spacer needs rotating by 180º while in the second its installed correctly just both the gaskets are wrong. However in neither can you see what the second carb has.... 1 Link to comment Share on other sites More sharing options...
NonMember Posted November 3, 2022 Report Share Posted November 3, 2022 16 minutes ago, johny said: In the first pic the inner gasket is wrong and it looks like the spacer needs rotating by 180º while in the second its installed correctly just both the gaskets are wrong. However in neither can you see what the second carb has.... Are you sure? To me it looks like the first picture shows the carb having a bleed hole to the bottom right, which is where the notch in the spacer is, which would be correct. I know it's shown the other way up in the parts catalogue but parts catalogues often show things in the wrong orientation or position. However, it looks to me that the flange on the manifold is too narrow for that notch. I'd like to see a photo of the manifold without the spacer. The second photo, with the carb fitted, shows a square manifold flange. That makes it the other carb. 1 Link to comment Share on other sites More sharing options...
gt6j Posted November 3, 2022 Author Report Share Posted November 3, 2022 Cant emphasise thanks enough for all of the help on here. It's sorted my headsches out. nailed it today. If may help someone in future - symptoms were engine struggling and dying only when hot and on idle only. Pulled fine through range otherwise. I took the carbs back off and true enough there was a gap down in between the carb to manifold gaskets. think this gap existed before I ripped it all apart too on older gaskets which were wrong so that was the main issue originally as far as i can tell. (I've got a new ignition system that I know now, and the carbs did need doing as the seals were leaking anyway) The carbs (emission ones, 150) on mine don't have an air breather hole that needs to be kept clear as far as I can tell. there is a hole for it (see pic) but blow down it with tube and nothing. Seems to be blank?? Found the way the gaskets line up bewteen carb/manifold/insulator i got wrong and was wrong before, the insulator/spacer piece has to be in right way round too. Found the gasket kit that came with the carb kit had one that covered all gaps around the carb and insulator, but took a while fiddling to find the right way for them to be in. It went: carb->new gasket->insulator (finger shape gap in this pointing down to front of car and floor)->another new gasket that matched the insulator shape exactly. Once that was sorted was much happier. Dropped the idle to about 6/700 as per guidance on here, reconnected both throttles to the link, set the needles to factory (washer on needle in line with base of piston as per Pete) and voila, idles lovely and smooth at 6/700, didn't die when hot. Took it out for a good spin as below, (wet road ), no issues idle lovely & felt alot more responsive to me and didn't die at a set of lights. Smiles! Link to comment Share on other sites More sharing options...
johny Posted November 3, 2022 Report Share Posted November 3, 2022 Brilliant. Think the hole is the vent from the float chamber (early versions just vented into air filter) so I wouldnt expect you to be able to blow through it... Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 3, 2022 Report Share Posted November 3, 2022 Not really the float vent hole is on the air cleaner face any holes behind the throotle plates is there for the temperature compensator air bleed if they are fitted ( and joes picture show he has them ) if its a blind hole then its just an unused casting /drilling thats redundant if the TC is fully closed you wont blow through this hole these are biased needle top adjusting with TC so have to be CDSE 150 Pete 1 Link to comment Share on other sites More sharing options...
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