I have 280ZX running twin SU carbs, HFI 6 type, with standard 280ZX dizzy (E12-80 Module).
Need to know the best place at the carb/ manifold/ wherever to connect the dizzy vacuum pipe and have searched "tinternet" but now more confused than ever.
Some say the take off position can be upstream of the carb. butterfly or downstream dependant on whether the dizzy is vacuum advance or vacuum retard type ( I believe the 280ZX is vacuum advance type but please say if that's not so). It's also said the distance from the butterfly is important.
So, upstream or downstream the butterfly? And, just how far from the butterfly is best location for the pipe to sense the vacuum?
Presently the take off for the pipe in my set up is from top of the inlet manifold flange, about 1.5" downstream the butterfly spindle (1st photo).
I note both my carbs have a small hole in line with the lower edge of the butterfly (something to do with fuelling?) however one of the carbs (the rear one) has a much smaller additional hole alongside (2nd photo). This smaller hole seems to go through the carb body and is blanked off.
Could the smaller hole under the butterfly be an alternative location for the vacuum tube and if so is it better positioned here than the present position?
You will gather from this rambling that I'm quite bemused by the HFI 6 carb and can make little sense of the many holes I see in and around it.
Any help in locating the best take off point for the dizzy vacuum tube would be much appreciated.
Need to know the best place at the carb/ manifold/ wherever to connect the dizzy vacuum pipe and have searched "tinternet" but now more confused than ever.
Some say the take off position can be upstream of the carb. butterfly or downstream dependant on whether the dizzy is vacuum advance or vacuum retard type ( I believe the 280ZX is vacuum advance type but please say if that's not so). It's also said the distance from the butterfly is important.
So, upstream or downstream the butterfly? And, just how far from the butterfly is best location for the pipe to sense the vacuum?
Presently the take off for the pipe in my set up is from top of the inlet manifold flange, about 1.5" downstream the butterfly spindle (1st photo).
I note both my carbs have a small hole in line with the lower edge of the butterfly (something to do with fuelling?) however one of the carbs (the rear one) has a much smaller additional hole alongside (2nd photo). This smaller hole seems to go through the carb body and is blanked off.
Could the smaller hole under the butterfly be an alternative location for the vacuum tube and if so is it better positioned here than the present position?
You will gather from this rambling that I'm quite bemused by the HFI 6 carb and can make little sense of the many holes I see in and around it.
Any help in locating the best take off point for the dizzy vacuum tube would be much appreciated.