In my 409's I've got 69's in front and 73's on the mechanical secondaries. My heads are alittle more conservative ported Torquer II's with 170cc runners, but that moves the velocity up. I've got so much torque down low its silly. I'm spinning 22" Q-IV's at around 4700. But I have pretty restirctive stock Mercruiser exhaust with muffled tips.

The cam is the XM262 with 1.6 roller rockers on 2.02/1.60 valves and about 9.5:1 compression.

My 750 Has does not have jets in the secondaries, it must be using the metering block to replace the use of jets..maybe All I know is I went to check them and there and were no jets to be found in the secondaires. No threaded holes or nothing. maybe they are there and I don't see them, I am not the brightest when it comes to carbs. I just found a scamatic of the design on there website and they show secondary jets in the metering block, I swear there wasn't any jets. maybe I should take a look for myself