speaking of cavitation, this helped me to understand things a little bit more...
http://www.mcnallyinstitute.com/01-html/1-3.html
http://www.mcnallyinstitute.com/index.html

Pfew! It took me an hour to track this thread!

Here are some pics of my pump housing:

And more:

And more (attached, this time!)

So what do You think Volenti? Can I, should I mod this?

I'm thinking about temporarily gluing a plate on top of the impeller (with a hole in it!). This would prevent the water from recirculating within the pump.

BigBen:

Personally, I wouldnt mod that. Looks great as it is. Unless you want the pump to be self-priming? :)

Yes it looks good. Does it cavitate (under heavy charge = COMPLETE watercooling circuit in closed loop) ? If so you could consider porting it.

There is an air issue, but I'm not sure where it's from yet, because I've only tested with thin-walled 1/2 vinyl tubing, which promptly collapsed.

So I picked up 3/4 braided.:D

I also didn't get any hose clamps yet.:eek:

Now all I have to do is convert the rest of the stuff to 3/4 :rolleyes:

Ahh, very interesting, nice to see the impeller design of a fixed rotation pump.

It doesn't need any "modding" as such, if you wanted to do something you could round the edges slightly on the output (from the inside of the impeller chamber, and mabie look at the intake, which from the pics looks to be a little restrictive, but it's difficult to tell for sure.

looks like it'll pump like a champ.

WoW!, nice!, what pump is that BB?...

It's a Little Giant 2-MDQ-SC. ~550 gph @ 0 head, shut-off at 14.4 feet.

I've figured out that its most efficient at 250 gph, at which point the head is about 11 feet.

Picked it up at a flea market for $40...:D

I checked out the little giant website, and this is the closest I found to it: 2-MD-SC specs

I might try to swap some parts for the model 3, if I can get them cheap.