boost gauge for paxton
- Thread starter Daniels1414
- Start date
Find a vacuum line, whether it be on the intake manifold or whatever, drop in a T, and run the line to your boost gauge and you should be all set. You won't read boost however if the carb setup is on top of the SC(I am pretty sure), you have to use a vacuum line "after" the SC, so like I said pick a line on the intake manifold and you should be set.
Daniels1414 said:
Yea, you're correct. To read the accurate boost level the line should reference BELOW or downstream of the throttle valves in the carb. If it's located above the carb throttle vavles, you will not get a true reading of MANIFOLD pressure as the carb hat or enclosure will tend to stack-up the compressor discharge pressure when the throttle is suddenly opened or closed, and you will be reading what is know as "Upper deck pressure".
What are you putting together? Just curious.
Salpper, I'm confused: he asked if it should be in the carb enclosure and you agreed but then said it should be below the throttle valves on the carb., which would indicate he should get his reading from a manifold port. Either way, wouldn't he get innacurate readings at a sudden throttle opening or closing? Should it be in the line from the supercharger? 
What are you putting together? Just curious.
I have a 289 in my 67 that I already have a paxton system waiting to go on. It is a novi 1200 and I believe it should put out about 7.5-8 lbs of boost with the stock pulley. I already have a A/F ratio gauge(norrow band) which is kind of worthless but I need another gauge to go with it in a gauge pod and a boost gauge is always cool!
I have a 289 in my 67 that I already have a paxton system waiting to go on. It is a novi 1200 and I believe it should put out about 7.5-8 lbs of boost with the stock pulley. I already have a A/F ratio gauge(norrow band) which is kind of worthless but I need another gauge to go with it in a gauge pod and a boost gauge is always cool!
The carb. enclosure has many fittings available on it and you just put a fitting there and run to your gauge. This information is direct from Paxton. Anybody could have called them, so why didn't you?I also asked about erradict(SP) readings during sudden open and shut throttle actions and the tech stated that there would only be about 1/2 lb. of difference. It really doesn't matter whether you go above or below th carb. throttle plates in the enclosure because you are measuring boost or vaccuumm in the enclosure.
mustangdave said:Salpper, I'm confused: he asked if it should be in the carb enclosure and you agreed but then said it should be below the throttle valves on the carb., which would indicate he should get his reading from a manifold port. Either way, wouldn't he get innacurate readings at a sudden throttle opening or closing? Should it be in the line from the supercharger?
Sorry. You're right. I wasn't very clear.
To get a TRUE manifold pressure reading, the reference should be below the throttle valves, from the mainfold. This is where I ran mine. If the reference is taken from the carb enclosure ABOVE the throttle valves, It will sense the compressor discharge pressure, and not nessesarily what is filling the engine induction system. There will be a slight difference, with the pressure from the carb enclosure being slightly higher due to the restrictions created by the venturis and the throttle valves. Yes, at sudden throttle openings and closings you will see spikes on the gauge from the pressure entering the carb enclosure, but it's accurate enough, and nothing to be concerned about. I use a reference from my carb bonnet(enclosure), to pressurize the mechanical fuel pump diaphram and fuel pressure regulator as it is more responsive than from the intake manifold, which is below the throttle valves. This is "in line" from the supercharger.
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