Hi
I have Stromberg carbs on my GT6 mark 3. I think I am correct is saying they are CD150SE?! They are the ones with temp compensators on. The car has run pretty lumpy on tickover since I had it. It runs fine under power and goes really well and smoothly when you have your foot down. So I think there is an air leak causing the idle to be rough.
If anyone attended the tinker day at club HQ mine was the white Spit/GT6 conversion that Pete started the day with. Since the day I feel much more confident with the carbs and can now remove from the car and strip down in about 40mins!
Anyway I am still trying to rule out symptoms as I am going along. The air compensators are closed, I now have some proper asbestos gaskets on the carbs and have fitted the gaskets so the the air hole is unblocked on the butterfly side of the carb. I have a proper air filter box too. I did have heat shield between the carbs and the manifold which I know are not standard, I did take them off when I got the asbestos gaskets, but put them back on again as there was an issue with the front carb (nearest radiator). The manifold is so narrow where it meets the carb that the air hole that I assume goes to the bypass valve and the temp compensator was overhanging the manifold. This is led me to believe that this is why the heat shields were put on in the first place to make a better mating surface for the carb.
I have experimented with the fuel/air mixture and have tried using colour tune, lifting piston, inspecting plugs etc. The timing is set to 8 deg before top dead etc. I have set the fuel float level to the recommended level in Haynes manual. I have checked diaphragms for leaks, checked the floats are the right way up. I have damper oil in the pots. I have checked the carbs are balanced with a meter.
So to my question. Below is a pic of the butterfly, they don't look particularly worn to me or that the gap around them is a particular issue but I don't have any experience of what constitutes unacceptable wear? I have held them up to a strip light with piston out of the carb.
If they are worn can you just replace them I am assuming you don't necessarily need to replace the spindle. The spindle seems OK and doesn't wiggle about when opening and closing.
Any advice much appreciated.
Dan Cook