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Discussion Starter #1
Alright guys, I need some help here.


454BBC (passenger/2 bolt/ ~325HP).
Berkeley JC pump.


WOT - 4900 RPM & 46 MPH - Sea level with 4 adults
WOT - 5100 RPM & 50.6MPH - 3700' elevation - 1 adult.


Pulling a skier, the pump cavitates and doesn't produce much torque.


Based on the above the assumption has been that the impeller was a C cut, which was causing the high RPMs and cavitation from a stop under load. I was getting ready to send the pump out to get rebuilt with a new impeller so I pulled it apart and this is what I found inside. A2 cut impeller, what looks to me like clean leading edges, no obvious issues. So what gives? Why are my RPMs so high and having trouble with the holeshot?


Now I have no clue what to do with the pump rebuild. I'm glad I might save some money on not needing a new impeller, but at a loss for performance issues.

https://imgur.com/i3e17Eg

https://imgur.com/zIF5Xy9


https://imgur.com/RPWymEK


https://imgur.com/jfIJt1e
 

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Alright guys, I need some help here.


454BBC (passenger/2 bolt/ ~325HP).
Berkeley JC pump.


WOT - 4900 RPM & 46 MPH - Sea level with 4 adults
WOT - 5100 RPM & 50.6MPH - 3700' elevation - 1 adult.


Pulling a skier, the pump cavitates and doesn't produce much torque.


Based on the above the assumption has been that the impeller was a C cut, which was causing the high RPMs and cavitation from a stop under load. I was getting ready to send the pump out to get rebuilt with a new impeller so I pulled it apart and this is what I found inside. A2 cut impeller, what looks to me like clean leading edges, no obvious issues. So what gives? Why are my RPMs so high and having trouble with the holeshot?


Now I have no clue what to do with the pump rebuild. I'm glad I might save some money on not needing a new impeller, but at a loss for performance issues.

https://imgur.com/i3e17Eg

https://imgur.com/zIF5Xy9


https://imgur.com/RPWymEK


https://imgur.com/jfIJt1e
Berkeley Jet Drive - Inducer Pre-Impeller Cavitation Reducer
these work.
 

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Discussion Starter #3

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WOT - 4900 RPM & 46 MPH - Sea level with 4 adults..... Your numbers are not that far off 325 HP with a AA Berkeley impeller would be around 4500 (assuming your tach is accurate ) the "tire spin" as I percieve it Is likley wear and tear causing excess clearance between impeller and wear ring and thus cavitation which feels like "slippage" , possibly some air leakage from worn or burnished packing , leaking clean out cover etc along with it Honestly sound like its simply time to "freshen" your jet I failed to see what Hull or what length but suspect its a full grown cruiser? If so your speed may not be far off If its a low slung 18 ft boat thats a different story Tom
 

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WOT - 4900 RPM & 46 MPH - Sea level with 4 adults..... Your numbers are not that far off 325 HP with a AA Berkeley impeller would be around 4500 (assuming your tach is accurate ) the "tire spin" as I percieve it Is likley wear and tear causing excess clearance between impeller and wear ring and thus cavitation which feels like "slippage" , possibly some air leakage from worn or burnished packing , leaking clean out cover etc along with it Honestly sound like its simply time to "freshen" your jet I failed to see what Hull or what length but suspect its a full grown cruiser? If so your speed may not be far off If its a low slung 18 ft boat thats a different story Tom
I agree Jim, he has not mentioned hull other than 2 seater? I just noticed the hand-hole(clean-out) the boat deffinetly shows cavitation. M
 

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Discussion Starter #11
WOT - 4900 RPM & 46 MPH - Sea level with 4 adults..... Your numbers are not that far off 325 HP with a AA Berkeley impeller would be around 4500 (assuming your tach is accurate ) the "tire spin" as I percieve it Is likley wear and tear causing excess clearance between impeller and wear ring and thus cavitation which feels like "slippage" , possibly some air leakage from worn or burnished packing , leaking clean out cover etc along with it Honestly sound like its simply time to "freshen" your jet I failed to see what Hull or what length but suspect its a full grown cruiser? If so your speed may not be far off If its a low slung 18 ft boat thats a different story Tom
The hull is a 19’ Tahiti with a deep v Hull.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #12
I've decided to go with a full rebuild by Tim @ Place Diverters and start with a heritage AA impeller. After I get the pump and get it back in the boat I'll take the boat out and see how she does. I'll repost the number that I see after I get it back out on the water.
 

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I've decided to go with a full rebuild by Tim @ Place Diverters and start with a heritage AA impeller. After I get the pump and get it back in the boat I'll take the boat out and see how she does. I'll repost the number that I see after I get it back out on the water.
not a fan of that impeller nut you have. made in china, and not all of them were square. well, most of them weren't square. so, the nut gets torqued on and it cocks the impeller to one side. impeller rubs, and it only gets worse. "self clearances" the wear ring outside the desired tolerance. pump should spin smoothly when it's back together with clearances to spec, no rubbing...
 

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Discussion Starter #14
Got the boat back in the water today after re-installing the rebuilt pump and redoing the interior over the last couple of months.

Lake Perris: 2 adults 2 kids.

WOT: 4800 rpm @ 48.5mph.
Heritage AA impeller and rebuild by Tim @ Place Diverters. Boat runs strong from the hole, and I'm happy with the performance I was seeing today.
 

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Great results...

I'm glad your jet rebuild cleared up most of your issues... That said, you also mentioned a new interior was installed while the boat was down... OK, but in the future try to limit the changes to ONE AT A TIME.... True, the interior refresh shouldn't play a role in the performance end, but slight/small changes in boat balance can effect performance and make you think other changes made the difference...
Have fun, be safe, and wear a vest at speeds above plane, especially if you are alone....
Ray
 

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Since you have the 325hp BBC, you 99% probably have the small port heads (peanut port). Those things wont rev much past 5K. They just dont flow enough air. They hit a "wall" around 4800 and depending on your pump setup and timing and cam, that's about all you'll get. I know because I run them too. So your RPMs for that engine seem right to me.
 
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