help berkly pump problems

[cokesbody]

I was out on the lake today and when you put the boat i gear it goes but it will free rap and it doesnt go very well and the hole boat kinda shutters. the boat has sat for a while i just rebuilt the motor it has a 455 rocket ported and polished heads balanced and buleprinted, block is zero decked, flat top pistons punched 40 over, cam is a doug herbert 540 lift. The pump is a berkly 12jc. I any one has any suggestins please let me no im kind new to this. thank you dustin

[Moneypitt]

Does it shake on the trailer?? or only when the jet is in the water? Could be trash of some nature in the pump. It doesn't take much to throw the turbine off.........When you say "rap" I assume you mean rev up and go nowhere.......like a slipping clutch, which is usually trash, or some foriegn object, weeds, fishing line, ski rope, towel, etc........The shake is the lopsided loading of the empeller due to the trash......Now if it shakes on the trailer, I would speak to the balance shop that did the motor. BTW .040 pistons are usually cast........And that is a no, no, in any marine motor...........MP

[Oldsquirt]

Certainly sounds like junk in the pump. With boat on trailer, slide underneath with a light and look up into the intake of pump. Look for rope, weeds or any junk wrapped on the shaft. Look at the leading edges of the impeller for damage. They should be straight. Big chunks missing would be bad. If that is all OK, you can suspect something wrong on the backside of the impeller or front of the bowl. With a boat that has been sitting outside for any length of time you also have to consider the possibility that some furry little creature may have made a home inside the bowl. This means removing the bowl for inspection.

[cokesbody]

Does it shake on the trailer?? or only when the jet is in the water? Could be trash of some nature in the pump. It doesn't take much to throw the turbine off.........When you say "rap" I assume you mean rev up and go nowhere.......like a slipping clutch, which is usually trash, or some foriegn object, weeds, fishing line, ski rope, towel, etc........The shake is the lopsided loading of the empeller due to the trash......Now if it shakes on the trailer, I would speak to the balance shop that did the motor. BTW .040 pistons are usually cast........And that is a no, no, in any marine motor...........MP
The motor doesnt vibrate on the tailer only when it was in the water and when its in gear and you give it gas. I no that cast piston are bad but that was all that i could afford at the time if i had the money it would have a 454 chevy im not much of an olds fan but it runs farly hard when it runs. if you have any kind of info on how to make it faster and get it out of the hole beter and ov corse big roaster that would be great you dont see many older boats on the lake wear im from in south dakota throwing big roasters there all people with crown line boats and to much money ha ha :messedup:

[cokesbody]

Certainly sounds like junk in the pump. With boat on trailer, slide underneath with a light and look up into the intake of pump. Look for rope, weeds or any junk wrapped on the shaft. Look at the leading edges of the impeller for damage. They should be straight. Big chunks missing would be bad. If that is all OK, you can suspect something wrong on the backside of the impeller or front of the bowl. With a boat that has been sitting outside for any length of time you also have to consider the possibility that some furry little creature may have made a home inside the bowl. This means removing the bowl for inspection.
it doesnt do it on the trailer ony in the water and in gear when you go. do you also know any were i could get a cable and control for the trim it has power trim now and it doesnt work very well any advise on makeing it faster

[cokesbody]

when i was inspecting i noticed that the impeller was dull will this affect performance what can i do.

[cokesbody]

there was about two foot of ski rope rapped around the shaft and the impeller no damage but i did notice that the impeller was very dull what are your thoughts on that the boat is 35 years old and hasnt had much dont to it since i did the motor i just got it last year its my first one,im only 22 years old so i dont know a lot about jet boats yet ,but i want to . thanks for your help

[Oldsquirt]

That chunk of rope explains your "free rap" and shaking problem.
The impeller does not need to be sharp as a knife, but is helps if it isnt all dinged up on the leading edges.
Now its time to take it back to the lake and get some performance numbers. Measure your speed with a GPS and get the rpm you are turning at that speed.
BTW, the moderators moved your thread from gearheads and now there are two for the same question here in Jets. Might want to delete the other one.

[Moneypitt]

And remember it's an Olds, not a small block chevy. The big oldsmobiles don't like sustained high RPMs, especially with cast pistons. I hope you maintained the oil system, restrictors to the top of the motor, and a large capicity oil pan. The Hardin Marine olds' had steel cranks, and too many of them have gone to the junkyard only to be replaced with an automotive cast crank, that usually won't live very long. I run an old Olds in a 68 Hydro, and it had/has all the good stuff in it, lots of Mondello parts, and a huge oil pan.....Still, about 5500 is considered buzzing it pretty hard...........The jet should work LOTS better without the ski rope, a small piece of wood chip can do the same thing, and weeds, well, you've now experienced what a poluted jet feels like, so next time you will know right away. NOTE: DO NOT open the clean out while in deep water as the boat may sink before you can get the top back on. If fouled at the lake/river, beach the rear before opening the clean out.........MP

[cokesbody]

how do you measure the gallons per second and do the math on how fast you go. do any of you jet boat enthusists have any adivse on go fast things for my boat its a 70 cobra jet with a 12 jc and an a cut impeller

[Oldsquirt]

GPS is Global Positioning System. Little hand held electonic device that allows for pretty accurate measurement of speed.
And Moneypitt's advice regarding the Olds and sustained high rpm use should be strictly followed. Same with the clean out cover advice.

[cokesbody]

how come cast pistons are bad for jet boats when ive had it out before at full trottle it runs around 3800 3900 rpms with an a impeller

[Floored]

38-3900? tell me your kidding. my olds is slow at 49-5000 with a Jacuzzi B which is the same as a berk A. check your tune-up.

[olbiezer]

i had a old sunkist with a 455 that would do 5000 with a a cut berkley. it would do about 68 mph and thats about all u can hope for unless u do some pump work.

[kp216]

3800 -3900 on a "40 over, ported and polished j heads, the blocked is zero decked, it has a doug herbert 540 lift hydrolic cam, flat top pistons. and its balanced and blue printed" 455 at WOT? Something is seriously wrong there. My 403 Olds turns an A impeller 4200.
What style of CobraJet do you have? The one with the wrap around windshield that looks like a Sidewinder or one that looks like this?
http://www2.***boat.com/image_center/data/520/327Picture_004-med.jpg

[cokesbody]

I have the one with a wrap around winsheild. I dont no a hole lot about boats but i do no it goes a hell of alot faster than 40 if u guys are around 49 5000 rpms than your motors must be about 500 horse. I dont know y you want it around 5000 any way thats y you would put a load scoop on to lower the r's and to load the pump

[Oldsquirt]

Going by the Berkeley charts, an "A" at 3800 is roughly 175hp. An "A" at 5000rpm is just short of 400hp.
Like I said yesterday, you need to go out and get some rpm/mph numbers. Might also consider checking your tach for accuracy.
My previous boat, a Tahiti Olds/Berkeley, mildly warmed over, would run 67 at about 5000 rpm. That was with the stock all original pump with "A" impeller.

[cokesbody]

I no what the chart said, that motor stock is way more than that the guy that oringinaly owned my boat said that it would do 60 mph when he last had it out, i dont know if there is something wrong with the tach or maybe the cam i have is kinda shitty but or may be there is something else wrong im not shur. i dont know a lot about olds motors ,or jet boats .im a chevy man i can make a small block run like no tommrow. i dont know whats wrong with the boat.

[Oldsquirt]

..... i dont know whats wrong with the boat.
You need to start with ACTUAL performance numbers. So verify the tach is accurate and either beg, borrow or buy a GPS so you can get accurate MPH numbers. Go test the boat and bring back the rpm/mph numbers.
..... cam is a doug herbert 540 lift
This provides little information. What are the duration numbers? What is the design rpm range for the cam? What are you running for intake and carb?

[cokesbody]

Im sorry i dont mean to sound like an ass but im just frustrated with my boat do you no were i can get a gps from.

[Oldsquirt]

Any decent sporting goods store or outdoor sports store should have them. One of the most commonly used is the Garmin E-trex. Costs about $100.

[cokesbody]

ill go get one and try it out, do you no were i can get just a manual cable and foot pedal or lever for the trim because the power trim it has doesnt work half the time or it wont trim up all the way.

[SmokinLowriderSS]

The cable you ought to be able to remove, take to a place that makes commercial comtroll cables (like Power Drive Systems I have here in Kansas) and buy a replacement cable. Only a steering cable is unavailable that way, it's a specialized piece of hardware. The cables may be on a shelf or may have to be fabbed, either way, no real problem. The trim handle, I don't know offhand a supplier but they are available. It would be helpful to know the brand of "place diverter" or "jetovator" you are running.
The jet drive is very simple. It's simply a water pump. It should be smooth and silent, and very reliable. ANY noises or vibrations that occur, FIND OUT WHAT THEY ARE, SOON! Expensive things can happen when you keep using a worn or failed moving part in a jet, especially the thrust bearing in the front of the casing! :cry:
Your olds motor is OK but do not treat it like a free-revving chevy. The oiling system will pump even the largest oil pan up into the valve covers faster than it will drain back unless certain mods have been done to restrict oil flow up into the heads at high RPM's and to assist drainback. I run a 454 so I have no such issues but I know many olds drivers, many are here, they know of what they speak in keeping an olds alive above 4,000RPM.
Basics of running a jet fast:
The main thing you do to run a jet fast is attatch plenty of muscle to it and use an impeller of the RIGHT size to allow your engine to reach it's power. Too big an impeller and your engine never winds up to it's power-producign RPM. Too small, and you rev past your peak power zone. The rest is tuning, not of the engine but of the drive & hull combination. To run fast, get the 'glass in the air, not on the water. Fibreglass skimming on the water creates drag and slows you down, 'glass carried above water in the air does not. You use a RIDEPLATE (a largish aluminum plate below your pump if you have one) to set the boat attitude at full speed. It kind of behaves as an extension of the hull. Trimable nozzles allow you to lift the bow with an adjustable factor that also allows you to hold it down in rougher water. Racers use a fixed nozzle but add wedges to tilt it to do the same thing. The adjustable part is bad for them at well over 100MPH.
There is more but it starts getting into the voodoo details, those basics should get you moving for now. Welcome to the world of owning & driving a jet, the funnest boat there ever was (IMO). :cool:

[SmokinLowriderSS]

Cast pistons are bad?
I been running the same cast slugs that came in my Indmar 454 in 1978, that's 27 years, 26 years on Nitrous (330 for the engine, 150 for the gas, about 480HP and 5300 RPM). Guess I ought to mention that I discovered on this winter's rebuild/upgrade she has been spinning a CAST STEEL crank all that time too. Cast can be successfully run, as long as you don't exceed what it is designed to do. I wouldn't build a 600 horse motor with anything less than forged parts, but 400HP big block is calm enough in my opinion to live on cast items, at least in the Chevrolet incarnation. :cool:

[cokesbody]

my boat is the same as you smokin lowriderless except an olds i just got it and have been trying to get the bugs out of it but cant afford to take it to a perfesional shop. How woudld you tell if the boat has been started out off the water what would happen how would it affect performance in the pump i never have but maybe the other guy did i dont know, what parts could be damaged. the wear ring and the impeller or more.

[SmokinLowriderSS]

If your boat is identical to mine, then you will have a Berk E or F pump. There is a tag on the top of the bearing housing just aft of the engine to be sure what pump you have. I don't THINK any of the Taylors like mine came with any other pumps but I could easily be mistaken.
If you open the hand-hole (cleanout hole) and look inside, you will see the front edge of the impeller and that is the location of the wear ring, in the suction housing immediately foreward of the impeller. You most likely have a metal one, stainless steel or bronze. There should be a SMALL gap between it and the impeller outer ring face. You cannot tell if there has been a little wear from the impeller rubbing on the ring at the sides unless you remove the bowl and then the impeller. if there is a LOT of space, your RPM will go up from high-pressure water blowing back into the intake and causing a pressure drop (as well as cavitation likely). That makes you a candidate for a rebuild, not hard or expensive but it will kill most of a day. If you have a metal wear ring you can manage to get away with starting it dry but NOT RUNNING IT LONG. no lube or cooling water. The impeller is lubed by water at the wear ring, the packing gland seal is lubed & cooled by water arround the front of the pump shaft, the engine needs cooling water. I do not reccomend dry running a jet period. Some of us do it, some do not. I run a polyurethane plastic wear ring. It self-heals from minor sand damage, it is softer than the impeller accepting more damage to it than just tearing up the impeller. It lies directly against the impeller and CANNOT BE SPUN DRY even for a couple secconds. Just enough to make sure a starter will spin the motor is OK, any more will heat and melt it, ruining it. Mine is still tight after 10 years of care.
A Berkeley jet needs lube in 2 places, a top-quality marine waterproof grease in the thrust bearing in front and 90-wt gear lube (I'm runnign the 85w-140 I have handy here at home) in the rear of the bowl under the 2 plugs at the top. Reemove both, shoot GL-5 into 1 till it runs clean out the other. This lubes a pair of babbit sleeve bearings at the rear of the shaft. Some other jets have slightly different requirements by design but most are similar.
Incedentally, from your engine RPM claims, It seems your pump is tight enough. If you cannot spim 4,000+, look at your engine unless you are turning too big an impeller. You should spin an A much faster, a AA might explain your RPM but so would a minor engine problem. A jet drive acts like a water-operated dynomometer. It will spin faster and faster as long as you have enough HP to overpower it. Once it matches your engine power at any throttle setting, your motor stops accelerating and maintains a steady load and RPM. The Tachometer is the #1 diagnostic tool on a jet. Any changes are reflected in the tach. Without any changes made on purpose, reduced RPM indicates a loss of power, increased RPM indicates pump wear problems (loose clearances). Engine upgrades should show more RPM, impeller changes should show RPM changes according to the impeller change (bigger = down, smaller = up). A good top-loader will usually reduce RPM (mine did but only slightly) by reducing cavitation.
And (I think this was spoken before) unless you have an E or F pump with the cleanout cover on the OUTSIDE of the boat, NEVER OPEN THE COVER WHILE AFFLOAT if it is inside the boat. You will sink in about 3 minuites.