modified injector pumps

[Powertruck95]

hey has anyone on here upgraded there pump to a 12mm hydraulic head? on either a 4jg2 or 4jb1? ive got my 12mm pump on the truck and running but have a problem only on verry light load it has a bad knock but accelerates through it. it sounds like the pump is to advanced. i set my timing up at .5mm tdc to start with and have backed itcoff to .2mm and still sounds too advanced. it starts fine no white smoke and not down on performance.

[isuzurob]

my 4jb1 turbo is set to 0.56mm 12 degrees before tdc, its 1.2mm at tdc

[Powertruck95]

Hey Rob what is the standard timing on the 4jb1 usually? I've got here a timing spec of .5mm at tdc for the 4jg2 with the csd blocked off.