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Pontiac - Boost Turbo, supercharged, Nitrous, EFI & other Power Adders discussed here. |
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#1
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Carb help
Did a test run today at 9lbs of boost and was happy with the run.My afr in my Holley was right in the 11.5 range.Would like to step up to maybe 12lbs boost.My main jets are 71 square and my pvcr's are .062 four total. Two in the front two in the rear.My question is,can I main jet up enough to stay in my afr range or do I leave my main jet alone and just play with pvcr's depending on boost or maybe adjust sizes with both?How much can a main jet air bleed change afr?I know how much fuel it takes to get my afr correct at 9lbs.So can I calculate how much fuel it would take to run 12lbs and the correct afr?
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#2
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Play with the PVCRs as that is the common way boosted carb calibrations are done.
Some people actually have 6 PVCRs in each metering block. Usually not all the same size. Two are large, two more are to get the fuel close, and the last two are fine tuning of the calibration for each metering block to get the exact A/F they want. This way for a boost increase you typically only need to replace two PVCRs with a different size. The big ones do not change much, the smallest ones take care of the fuel balance to both main wells and the medium ones adjust for the boost change. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#3
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Unfortunately blow thru carbs are trial and error. I would up the rear jets and see what happens you can always change them back.... its hard to un-drill a hole.
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