Jet pump tolerances

[SKEETR]

Been fiddling with my turdbojet for some time now. It is a 1994 115jeera. Irregardless, in a jet pump, I'm sure jet skis are similar in design, shouldn't there be a very minimal clearance behind the trailing edge of an impeller and the stator vanes which direct the water flow out? Isn't that a major aspect of a jet pump? On my turbojet there is about a 3/8" gap. Seems a bit much don'tcha think. I guess it could be an engineering compromise for an occasional stone to pass. Any input would be appreciated.
I'm considering having the gap built up to see if it will provide more thrust.

 

[H20Rat]

Re: Jet pump tolerances

the impeller to stator clearance isn't critical, and usually isn't adjustable either. Pumps are designed a certain way, changing the clearance of that could load the pump up too much.

 

[SKEETR]

Re: Jet pump tolerances

I found out what my issue probably is. The prop shop that I had dress my impeller honed the leading edge backwards, like a prop in other words. Found an interesting file online, impellersharpening.pdf, which shows how to properly do the job.
As far as overloading my pump, well I doubt it could hurt, I spent last week camping/fishing and due to the high elevation could only get 4800rpm which should still get me up and goin. I was regretably only able to reach a scorching 10mph plow. She will bite at sea level and do 30+.