You should be able to get loaner tools from your local chain auto parts store.

Thanks for the responses I have a better understanding of what it's going to take and should just enjoy the boat for the rest of the season.then dive into it ....


Sent from my motorola one 5G ace using SoCal Jet Boats mobile app

There may not be a "next season"

Would you be prepared to do additional machine work to the heads to support additional lift?  Otherwise, I think ~.480 lift will be your limit, because of retainer-to-guide clearance.  I also think ~.480 lift will be the limit before you start experiencing piston-to-valve interference.  Regardless, you should measure before you choose a cam.

It is worth pulling a valve cover to get your head casting numbers.  Many stock small block port's flow stalls at .450 lift.

I would recommend doing this in the off season, it could turn into a can of worms, that would consume precious time on the water.

I'm struggling to see the six bolts around the front.  The eight around the back look like the correct countersunk bolts.

Just to verify that everything is as it should be, the intake should be set with Heavy Duty Sea Goin' Poxy Putty and nothing else.   All of the load from thrust is transferred to the keel through this bond.

The intake screws provide a secondary mechanical attachment to the epoxy adhesive bond.  The screws themselves should be epoxy set to fill gaps, provide additional support, and seal the holes.

The screws can create a lot of drag, so it is good practice to fill and smooth over the top of the screws with epoxy.  When finished, it should feel like the screws are not even there.

Looks awesome!  I really want to dive into my pump.  I think its all screwed up but there is not a lot of info for a large 21' jet with delta pad.

What would you like to do?

I was told you can see how well your loader is working by the pressure on you water guage in the intake manifold, is that true?

Not true

Tap the suction before the impeller  1/8-27NPT for pressure gauge(s).  If one gauge, tap at 9-o-clock, directly opposite the cooling water port.  If you really want to "dial it in," tap as high and low for two gauges, roughly 11-o-clock and 7-o-clock.  You are concerned with the impeller inlet pressure, which will be a dynamic pressure, because the water is flowing.

Disclaimer:  it's really difficult to do with gauges.  Usually a data system is used to record through a pass.

I will post pictures, tonight, of where to tap.

Has the current loader been tuned to your pump/boat? That's where I'd start.

Dan'l

As Dan'l stated, you can try cutting the loader ramps back, little-by-little, to see if you start picking up in the direction that you want to go.

Wow, stoked for you.

Take tools, a battery, fuel, and a way to at least fill the fliat bowls to see if you can start it.

I would go and scrutinize every little thing that you need to repair, like does it run?  Has it sucked up any rocks?  Why has it been parked?

Everything today costs billions of dollars and it looks like the seller knows that operating that boat does as well, otherwise they wouldn't be throwing trash in it.

When you determine how much you want to spend, have that cash in one pocket.  Fan out the cash in front of the seller.  $3000 in bills laid out across the deck looks like a lot more than $4000 sounds.

In my experience, if I want something bad enough, I just get it and don't look back.  How long would it take you to earn back the difference between what the seller wants and what you want to spend?  Is it worth watching someone else driving around in your dream?

Someone bought what should have been my boat out from under me.  I had already made the deal with the guy after a thorough inspection.  Some POS walked in, with only 75% of our agreed price, right as we were starting the paperwork.  The kid fanned out the cash and the seller changed his mind.  I said, "I'm giving you full price."  The seller said, "The kid's got cash now."  That's never going to happen again.

Sorry to hear about your troubles.

How did the old spark plugs look?   You would see aluminum specks on the porcelain from detonation.

I'm sure that the machine shop checked the flatness of both the block and the heads.  Just to be sure, what were the findings?

Different types of gaskets require different surface roughness, achieved during the machining process, in order to seal properly.  Is yours appropriate for the gaskets you are using?

I have to ask, because I see a lot of improperly plumbed boats.

Do you have the water line, from the suction housing, plumbed into the front of the engine block, at both water pump ports?  There should be a tee or wye so that each side of the engine block is supplied with equal water flow.  The water jackets on each bank are separate and there is no flow from left to right.

You didn't mention what type of intake manifold you have.  Most use some type of automotive manifold with a thermostat provision.  The water should exit the timing cover end of the heads.  Through the thermostat provision, cast into the manifold, is a good choice.  If you have a manifold that doesn't have a single outlet from both heads, you need an outlet hose coming from each head, to a tee or better yet, a wye, and eventually dumping overboard.

There are various ways to plumb log exhaust manifolds, either before the engine, to preheat the water or after the engine.  I don't want to get into a debate over log manifolds, I'm only concerned that both sides of the engine have sufficient water flow.  You did say, you "have water flow coming out of the pisser on the side of the boat," that would indicate dry headers.  How much water flow?  Hopefully more than a trickle.

The following is my opinion, and it is not a popular opinion:

150-degrees is too hot for your water temperature.  Water temperature really means nothing.  What is important is the temperature of the components of the engine and how they relate to each other with clearance to move properly.  Oil temperature is a better indication of what is happening inside your engine.

The cooling water is plumbed off the suction housing, between the trailing edges of the impeller and the wear ring.  If you have an A cut impeller, there is 1/8" gap around the outside of the impeller, between the impeller and bowl, which is a cross-sectional area of 1.78sq/in.  If you have a AA, that gap reduces to just 1/32" with an area of 0.45sq/in.  Both areas are much bigger than hoses and fittings downstream.  However, the diverter nozzle is a huge leak and I don't think the engine gets sufficient flow during extended periods of ideling, such as ideling through the channel at Havasu.

Every hose, fitting, and the water jackets within the engine itself are a restriction to flow.  If a smaller impeller is installed, the water flow through the already restrictive system is reduced at any given RPM.  Example, water flow at 3000 RPM will be greater with an A cut impeller than with a BC cut impeller.

What does all that mean?

Flow is going to take the path of least resistance.  The diverter nozzle is much bigger and a shorter path than any part of the cooling system.  At idle, you will have much less cooling flow than when under way.  The water is going to get hot at idle

While under way, water flowing through the cooling system will have a higher velocity compared to that of a car.  There will be less time that the water is in contact with the surfaces of the water jackets.  To see an explanation of this, see https://sciencing.com/calculate-time-heat-water-8028611.html

If the velocity of the water is slowed so that the water temperature reaches 150-degrees, the water is moving too slow to properly extract heat from the engine.  That's more than doubling the ambient temperature of the lake water.

To operate a car engine, with a closed-loop cooling system, at 160-degrees, the temperature of the water coming out of radiator is not half the temperature of the water entering the radiator.  The (cooled) water coming out of the radiator is way above ambient air temperature, enough to burn you if you grab the lower radiator hose.  The number that I remember is that a properly functioning automotive cooling system should keep the coolant temperature about 80-degrees above ambient air temperature.

In a jet boat, while under way, you should be able  to touch the front of the head without blustering your finger.  The front surface of the head should feel "uncomfortably" warm.  If the head surface is so hot that it will blister your finger, how much hotter are the cylinder walls and valve guides?  There will also be a greater temperature differentials across the decks etc., increasing distortion.  Keep in mind that you have ice-cold lake water being used to cool the engine, not water that is already hot enough to burn you, as would be coming out of a car radiator.

I'm also not a fan of thermostats on jet boats, unless you have a closed-loop cooling system.

4-degrees up, relative to the keel, is a good safe starting point, for a V-hull.  Yes, the ride plate will have a slight bend near the shoe.  It should not have an "S" shaped bend (hook) near the ride plate.  If it does, your cradle might need to be machined.

Good luck

I?m not sure why it broke, I assume I sucked up a rock or stick. There was no vibration and was running fine. I only took it apart to replace the wear ring (my rpm was rising). It?s only on that 1 vein and the crescent shape crack goes all the way threw on 1 side and is slightly bent. But with a brass hammer it won?t pop back into its original position.


As far as adding a sleeve to the aluminum impeller I think it would be fairly easy to do and I imagine stainless on stainless would wear down much slower with the small sand particles? Does a stainless impeller last longer then an aluminum one all things bring equal?


I never thought about the road grime and will definitely start doing that. But I do all the other tips

The RPM wouldn't increase with wear ring clearance.  There was a thread, a few years back, where someone purchased a boat that had a top speed of 35 MPH.  Turns out, the pump was assembled without a wear ring.  The hit and top speed would suffer, but it wouldn't just start riding the rev limiter if you let it go unchecked.

That damage to the trailing edges will cause RPM to increase.  Also damage to the leading edges.  How do the leading edges look by the way?  Any signs of cavitation?

Yes, a stainless impeller, combined with a stainless wear ring is the most wear resistant.  The softer the material, the faster it will wear.

One thing I have thought about was spray welding hard facing material and OD grinding the impeller.  I don't know if there is a similar process for aluminum, because most customers, with an aluminum impeller, get pretty long life.  You might have access to and/or be familiar to just such a process.

P.S.  I'm sure you are aware that welding will kill the heat treating in that area, which is highly stressed.

P.P.S.  Front and rear axial clearance is slightly more important (within reason) than radial clearance.