grannyknot Posted November 13, 2014 Share Posted November 13, 2014 I have a standard Cannon intake manifold with triple carbs on my L28 engine, I have also installed a 123Igniton programmable distributor and would like to use the vacuum advance feature. Would 4 vacuum take offs from the 4 inner intake runners be enough to even out the pulses or should I take vacuum from all 6 ? Thanks, Chris Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 13, 2014 Share Posted November 13, 2014 A restrictor in the line allows one to be used. Quote Link to comment Share on other sites More sharing options...
grannyknot Posted November 13, 2014 Author Share Posted November 13, 2014 Tony, that's interesting and could make thinks a lot easier. What form of restrictor would you recommend? Thanks, Chris Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 14, 2014 Share Posted November 14, 2014 Carburettor jet, LPG orifice out if a grill, a brass plug with a small hole drilled in it, a needle valve. Some guys put a small engine gas filter in the line downstream of a larger orifice before the MAP sensor. The filter media and bit of a "vacuum tank" smooths out what pulses are remaining after the orifice. More cylinders means larger orifice can be used as pulsations are closer together. Adding the filter then smooths it out and you don't really lose any resolution. The spikes are not your trUe vacuum anyway...it's more like an "RMS Average" signal you want. 400hz power is more precise than 60hz power, which is more precise than 50hz power. Follow? Quote Link to comment Share on other sites More sharing options...
Leon Posted November 14, 2014 Share Posted November 14, 2014 FWIW, most Cannon manifolds already have a built-in balance tube. Do you have a photo of yours? Quote Link to comment Share on other sites More sharing options...
grannyknot Posted November 14, 2014 Author Share Posted November 14, 2014 Tony, I do follow. The gas filter idea is brilliant, I'll try it and post the results, thanks so much. Leon, I think what I have is a Cannon clone, I remember checking when it was off the car and there was no internal balance tube in the supporting structure. Quote Link to comment Share on other sites More sharing options...
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