H2 carb setup
Posted: Mon May 02, 2022 7:23 pm
Hello All,
I have an H2 carb, model AUC924 on my '59 948 Tourer.
I recently stripped and cleaned it and fitted new gaskets but nothing else was replaced as all seemed in good condition. Pretty sure the needle is standard.
When trying to set it up on the car I’ve found that the only time I can get the lift pin to increase revs then drop back is with the bottom nut screwed right in against the spring/body. Even then the increase in revs happens very near to the top of the pin’s travel.
As background, the engine has been previously rebored and fitted with 998 (+30 thou) dished pistons. Compression is good and equal on all cylinders. Tickover is smooth at around 700 rpm, timing is 4 degrees BTDC, fuel pump is working well, there’s oil in the dashpot and as far as I can tell there are no air or fuel leaks.
The car pulls fine on the road, attached photo of plugs after a run. Previously when the nut was set to 12 flats the plugs were black.
I don’t want to fiddle unnecessarily but why would it be that I can’t get the carb to adjust in the “normal” range?
I have an H2 carb, model AUC924 on my '59 948 Tourer.
I recently stripped and cleaned it and fitted new gaskets but nothing else was replaced as all seemed in good condition. Pretty sure the needle is standard.
When trying to set it up on the car I’ve found that the only time I can get the lift pin to increase revs then drop back is with the bottom nut screwed right in against the spring/body. Even then the increase in revs happens very near to the top of the pin’s travel.
As background, the engine has been previously rebored and fitted with 998 (+30 thou) dished pistons. Compression is good and equal on all cylinders. Tickover is smooth at around 700 rpm, timing is 4 degrees BTDC, fuel pump is working well, there’s oil in the dashpot and as far as I can tell there are no air or fuel leaks.
The car pulls fine on the road, attached photo of plugs after a run. Previously when the nut was set to 12 flats the plugs were black.
I don’t want to fiddle unnecessarily but why would it be that I can’t get the carb to adjust in the “normal” range?