Part# AS0002 Holden 179 186 202 4 barrel red motor manifold
AussieSpeed 9 port large volume runner manifold great for hot street engine, This is a much improved design when compared to the old John Cain manifolds and other manifolds currently on the market. With a flow bench tested plenum shapped for improved air speed in the ports and centre port divider so cylinders 3 and 4 do not run rich ensures even fuel distribution to all cylinders, this alloy manifold is a real performer.
This four barrel manifold suits hot street engine with rpm range 1500 to 6000+ rpm. Recommended on naturally aspirated street engines, if you are using an auto trans then match high stall converter to lower end of your camshafts pulling range and use diff ratio of 3.5 or lower [3.7] to get it to rev.  If you intend on using a stock converter and standard or highway diff gears then for best results select a camshaft [dur @ .050 < 210 & lobe sep >110deg] to give high air speed in the ports at idle and low rpm and use a vac secondary 4 barrel.