SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: mash on it on July 30, 2010, 09:11:16 AM
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Where to start tuning?
Pump: Berk 12j-c, shoe (back-cut?, tapered?), Ride plate, sport loader, jetovater, AA? impeller , 21' Eliminator daycruiser 45-4600 rpm. I have not gps'd it yet, feels like 40-45
454, +.030" over, 9.1-1cr, edelbrock intake, holley 750, indmar logs.
Ride plate angle?
loader depth?
other info neded?
It feels "too heavy" in the water, any ideas?
Thanks
Daniel
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Mash on it,
I think to really get balls deep into coming up with a direction, I would install a water pressure gauge in the suction piece to see what is doing what....
IMHO starting point;
Ride plate at 0 degrees
It sounds to me like the loader is deep, but a pressure gauge will tell you that with a higher than expected reading. Don't forget to through bolt these badboys...they take a beating and when they come off, it's huge.
I like to get the first pressure reading with a standard rock grate, it is a good starting reference.
40-45 would be much lower than what I would expect...GPS is a must if you really want to squeeze every ounce of performance out of it.
Anything else is just a W.A.G. ;)
Good hunting!
GT
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Pics
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Mash on it,
The first thing I can recommend you do is to climb under there with some 80 grit aluminum oxide sandpaper and get rid of the flaking paint an rough surfaces...This may not be noticeable right away, but it will help
Also be careful with the old style Diverters, they hang down quite a ways and while not a big deal on the JC bowl, the ca hook water when all the way down...
Looks like you have a lot to work with there though :thumbup:
GT
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GT has it in hand, but dude, WTF is up with the fins on your pump intake? :screwy:
Modified circle racng deal? on a 21' boat? I'd be VERY suspicious of what the loader looks like right about now........ ;)
Ray
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I run with the diverter all the way up......about a 1 foot rooster (like my bowrider, no diverter)
Have no clue on the intake fins, prev. owner said gs marine added the hardware, idk.
Do I need better pics?
thanks
Daniel
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pics
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OK, THAT'S better! Whew, looked to me like the intake was all jacked up! :screwy: here it's the loader. WAYYYYY to low looks like.
Ray
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I run with the diverter all the way up......about a 1 foot rooster (like my bowrider, no diverter)
Have no clue on the intake fins, prev. owner said gs marine added the hardware, idk.
Do I need better pics?
thanks
Daniel
Only 1 foot of roost with the diverter sounds weird to me. I have a JC pump with a hydro diverter on it and it throws a decent roost. You can adjust the the hem joint that attaches to the actual nozzle so that it will let you get my roost on it. Atleast on mine it does.... Doens't have much to do with your problem, just the 1 foot caught my eye.
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This is what I was referring too....
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tightening that jamb nut probably wouldn't hurt either.
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the jamb nut is siezed on the cable, thats where the "old "adjustment was,
I threaded the heim joint down for more roost, only bout a foot (now).
loader looks like its hanging down bout 1/2"- 3/4" from the keel
First pic "up" ,
second "down"
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it is my humble opinion looking at some of your pictures that your intake needs to be reset....The epoxy looks to be broken pretty badly all the way around. I suspect your intake is making a serious hook.
Loader should be even or a little above the keel line....
the jamb nut is siezed on the cable, thats where the "old "adjustment was,
I threaded the heim joint down for more roost, only bout a foot (now).
Remove the joint and install a second nut...Safety first above all else... :thumbup:
GT
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GT
sent pm
Daniel
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Well I pulled the loader and trimmed it to 1/8" below keel line, and "massaged" the jetovator till the rev. arm meets the diverter arm (More tail for less coin ;D )
I'll try it tomorrow at Bullhead for the trip this weekend at willow beach.
Thanks for all the help :thumbup: :beer:
Daniel
Mash On It :)