Rebuilt my holly 600 DP and it was easy like everyone said it would be although I have a question or two....I tore into the primary side first, replaced the powervalve and all the gaskets and pump diaprham but when I went to the secondary side there was no powervalve and no threads to even put one in...is it suppose to be like that? I was under the impression that there is one on both sides....also my kit came with needle and seat but the instructions showed them in the fuel bowl...which I had none in there does mine have a different setup? and last what are the two little screws sticking out the side of the metering blocks? (one on each) are they for idle adjustment??

no pv on secondary side of that small of a double pumper, the 850s and bigger had them though. The needle and seat are under the float adjusting nut on top of the float bowls. The two screws out the side are for a/f ratio at idle.

Many double pumpers don't have a secondary power valve. Totally normal.

The inlet valves screw into the top of the fuel bowls from the ouside. The float and it's related hinge are attached with 2 screws on the inside of the float bowl.

2 little screws sticking out the sides of the metering blocks, one per metering block? Not aware of any screw(s) like that.

The only screws coming out the sides of the metering block(s) are the idle mixture screws and there are 2 of them per metering block, typically only on the primary-side metering block, unless you have a carb with 4-corner idle adjustment (in which case there will be 2 identical idle mixture screws on the secondary-side metering block as well, for a total of 4).

BUT... I think you might be referring to the large-head screws on the sides of the FUEL BOWLS (one per fuel bowl, on the pass. side of the carb). Those are your float level adjustment observation ports. On a runnign engine removing those screws allows you to observe the fuel level in the bowls to confirm that your foats are set at the right height.

I don't remember if there where four or two but I know there in the meatering blocks...there really small and I think there was a spring on them as well you would need a screwdriver end about the size of a pen to get to them. As for the needle and seat, the ones that came in my rebuild kit seem to long to fit in there but I guess I'll have to pop the screw out and have another look.