Hooker Impeller Pitch - Cavitation

[Ericfox]

Does anyone have experience with a hooker impeller on a big engine? 870 lamey

Dave recommended a 13/18 hooker impeller for me and its cavitating pretty bad... I cant figure it out since I swear it didnt cavitate the first time I took it out... its really puzzling

I resealed everything and inspected the whole pump... I even sealed the packing with the right stuff to totally rule that out as a cause....

I can only think its the prop pitch or the 86mm nozzle bore... I run the stock cone with it, so i dont see that as being a problem

 

[orangefinger]

its going to be tough to compare , I run a ported 760 with a 10/16 hooka and a 771 with 11/17 hooka both with stubby cone and stock nozzle
I am happy with both but I think the 11/17 is cavitating a little too and it might be that my pump seal is not sealing 100% correct, did you shine light in from the intake to actualy see the clearance between impeller and wear ring..I have the feeling that my 11/17 is showing too much a gap just thru the visusal...

 

[sflsurfrider]

dont rule out the intermediate housing as a cause of cavitation.

 

[waterfreak]

dont rule out the intermediate housing as a cause of cavitation.

exactly!!...a broken seal between the rubber and the housing will cause excessive cavitation by sucking air from the engine bay into the pump.

 

[Ericfox]

So what is next? Is there any good way to figure out if there is a leak at the intermediate housing? it cant leak through the holes around the circle can it? or would it leak around the perimeter of the housing? I guess I could goop up a bunch of 5200 or whatever around the perimeter to see if that fixes it??

 

[Ericfox]

its going to be tough to compare , I run a ported 760 with a 10/16 hooka and a 771 with 11/17 hooka both with stubby cone and stock nozzle
I am happy with both but I think the 11/17 is cavitating a little too and it might be that my pump seal is not sealing 100% correct, did you shine light in from the intake to actualy see the clearance between impeller and wear ring..I have the feeling that my 11/17 is showing too much a gap just thru the visusal...

The gap is 7-8 thou max... well below the 22 or 24 thou limit whatever yamaha suggests...

 

[Lucaumpits]

I have Dasa 921cc and I was running Hooka 11/17, 7mm setback, but didn't work, had no leak or bad seal, now using magpump, is worth every penny!:smoker:

The gap is 7-8 thou max... well below the 22 or 24 thou limit whatever yamaha suggests...