A couple of years ago I picked up a HIF38 carb that had been sat on a shelf for years, my car then came off the road and is now back up and running so I want some advice.
I've given the carb a clean up and put it on my car. Had a mobile tuning guy come to tweak and fiddle and sort the timing out. He told me that there doesn't seem to be much resistance on the piston. After setting up the mix to around 3% I took the car for a drive round, a bit lumpy, then came back and he retested it and it was 0.5%. Another fiddle and drive, strong fuel smell, then the retest was 9%! He said there must be an issue with the carb and we left it at that.
Now, i've been playing about with the mixture and a colourtune and got it much better to drive but it's still got a flat spot when accelerating and every now and then there is a pop from the carb.
When I got the carb it hadn't been touched at all, to the extent that the plug was still in the mixture screw hole. My question is, assuming it was fitted to a 1275 in a previous life is, will the spring be right for my car? And how do I identify it? Any other tips for tuning it? I'm after a fun weekend drive on the twisty bits.
I've got a 998 A+, Stage 1, standard air filter box, ABD needle, SW5 cam.