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Messages - Rivernut

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Engine Mechanical / Electrical / Re: Sand in water jackets
« on: June 21, 2019, 03:59:12 AM »
My boat has raw-water cooled Chevy 350.  I installed small ball-valves at the front and back of the exhaust manifolds and on two low spots of the water jackets.  I open them periodically and Rev the engine to blow out any debris such as sand.  I also use a piece of stiff wire  to push open any clogs at the ball-valves.  I especially do this in cold weather to prevent freeze damage.  I use a wire from one of those little surveying flags.

Jet Pumps / Driveline Grenaded
« on: June 09, 2019, 05:51:19 AM »
I was going along about 4,000 rpm’s on the CT River the driveline went out.  No warning.  I’ve had 3 or 4 other instances with universals binding and blowing apart with my 20’ Aluminum Gator jet.  This is a SD309 AT pump powered by a vortec 350.  Geometry looks fine.  I grease them a couple times a year, doesn’t seem to matter.  I get about 100 hours on them and they go.  This is the first time the frame of the driveline has cracked apart, the other times it was just the universal joints.  I have a refreshed one (pictured) to install.   It isn’t super hard to fix, but it’s annoying that it keeps happening.

Engine Mechanical / Electrical / Hei module
« on: September 30, 2018, 05:21:20 PM »
Got my 350 powered jet boat running but now have a bad ignition module.  I have an old one from a prior identical Pertronix small HEI distributer.  I want to carry a spare but have not been able to find an 8 pin module with the built in 20 degree advance.  The two modules I have are marked with different numbers.  Nothing comes up doing an internet search.  Anyone know which is the model number on this?  Who sells replacements?

Engine Mechanical / Electrical / Are aluminum risers more durable?
« on: September 16, 2018, 05:40:10 AM »
I’m in the midst of sorting out the water in oil / cracked head issues on my Chevy Vortec 350. It definitely had water getting into a cylinder or two from head cracks and into the crankcase through a leaking intake gasket. I captured most of it in the puke tank.  One of the exhaust manifold bolts was corroded along its length, and an exhaust flapper valve was missing. Trying to sort through the causes, fallout and red-herrings. I’m wondering if a riser or manifold is leaking. The exhaust manifolds and risers are Marinepower aluminum ones. They have never been apart and the boat is 16 years old. It only sees freshwater and is fresh/raw-water cooled. I always drain the manifolds for the winter freeze. The manifolds are still unbolted from the heads. The ports are black with powdery carbon, no gunking up or water washed look to them. I’ve read a lot of the stories of risers going bad and destroying engines, especially in saltwater with iron risers. Very little is written about these high performance aluminum systems. I bought a pair of gaskets just in case I needed them. They were expensive, about $50 with shipping. I’m not sure if I should pull them apart risking damaging the surfaces and replace the paper gaskets. Any of you have experience with aluminum manifold/riser combos?  Do they need frequent replacing like iron ones if only used in rivers and lakes? Here is a pic of the manifolds/risers.

Jet Pumps / Re: Rutter or no rutter
« on: August 11, 2018, 03:57:00 AM »
If you are seen in public with the rudder then you have to turn in your man card.  Like training wheels for a jet boat.

Engine Mechanical / Electrical / Re: Oil leak help.
« on: July 10, 2018, 07:00:39 PM »
Does the engine have an oil pressure sensor / sender unit like this?  They can leak quarts in minutes under throttle.

Engine Mechanical / Electrical / Re: Why would this happen!!
« on: April 23, 2018, 06:41:49 PM »
There is an intermittent open circuit somewhere.  Turn on the affected accessories and wiggle wires until you find the loose one(s) when the accessories power up.  Check under dash wires and switches, and battery connection /engine compartment wires.  Grab and shake them.  You could speed up the troubleshooting with a voltmeter and check for +12v on the positive supply lines.  If plus is there then you have a bad ground somewhere.  Pull out fuses and clean corrosion off their contact points if present.

First thing you need to do is swap out that carb for a marine certified carb.  It is unsafe and illegal to run that.  That Holley 3310-2 is a great carb, but not worth burning up for.  I like the Marine Demons (now part of Holley) because of the fuel sights on the carb bowls and the built-in quick change secondary spring housing.  To cover a lean bog the previous advice is good.  I also include a 50cc accelerator pump and playing with different sized pump squirters to help cover the lean bog.  If you plan on playing with the carb you really need to get accustomed to reading spark plugs.  The proper set up will yield snappy acceleration with brownish plugs.  NGK copper plugs read the best, stainless not at all.  Readings must be taken by shutting down quickly after a full throttle run.  It is a fine dance between tuning jetting, power valve(s), accelerator pumps, secondary springs, float levels, initial and total timing, plug heat range, engine temp,  and fuel octane.   The goal is to run near the edge but backed-off enough to ensure longevity.  It is possible that the impeller clearance is too great causing increased rpm's or the and/or the tach reading is correct.

Engine Mechanical / Electrical / Re: What oil to run?
« on: August 18, 2017, 12:43:24 PM »
A "non-roller cam" could  have either hydraulic or mechanical lifters.  Mechanical lifters take more of a beating and would benefit more from Zinc.

Engine Mechanical / Electrical / Re: What oil to run?
« on: August 18, 2017, 06:17:32 AM »

You didn't say if your cam is a flat-tappet or conventional hydraulic.  You need additional zinc during break-in on non-roller cams, then I use Mobil1 15-50 synthetic. 
Advantages of synthetics include less carbon deposits in cylinders and throughout the engine, less wear, and longer oil change intervals.  Mobil1 advantage is its wide availability at stores lite Walmart and Autozone and reasonable price, $22.88 per 5 quart jug.  Disadvantages of synthetics are the higher price and they leak more from engine seals and gasket gaps as the engines wear.  The conventional Dino-oils clog up over-clearances so you have less "sweating" and drips of oil.  Many good oils out there to choose from.  My engines usually die from breakage rather than wear!  I change it once or twice a season, whenever it looses its transparency and darkens up. My boat engine consumes oil from all the sustained hour+ runs at 4,500 rpms while bouncing in 1-3' waves.  I add a quart every 5-10 hours or so of run time.  My spark plugs never foul with Mobil1.  I have a mild Chevy Vortec 350 with a carb.  My set-up also has dual oil filters, and of course I use Mobil1 filters.  I also use mobil1 red grease on my jet pump. Happy shopping.

I retained both power valves to aid in drivability during acceleration and fuel economy.

I took my choke out years ago and just left the hole alone.  No apparent ill effects.  I suppose you could silicone it closed or put a tiny piece of gorilla tape over the hole on the bottom side if it worries you.

Jet Pumps / Re: Diverter with no roost??
« on: July 03, 2017, 02:56:26 PM »
Does trimming up give you some bow lift and increased speed?  I would try a full throttle run and trim it up all the way, then slow down and shut it off without touching the trim again.  Peek over the back and see where the diverter angle / position is in relation to maximum up travel.  Again, make sure the connections are all tight.  Is there any fluid leaking out?  It sounds like air is getting sucked in at one of the fittings or solenoid valves.  The most common trim pumps are made by Bennett.  The ones in jet boats have four cylinder shaped solinoid controlled valves.  They are hand tightened.  Check them (righty righty).  It is also possible that the wrong fluid is in the system.  I use Mobil1 transmission fluid.  One other thing to check is for a slipped O-ring in the pivoting joint.  They sometimes pop out of the recessed groove and get pinched preventing full articulation.

Jet Pumps / Re: Diverter with no roost??
« on: July 03, 2017, 09:25:20 AM »
I have the same set up in a different boat.  Need more info...Where are you seeing bubbles?  Does the nozzle trim up and down fully with the boat on the trailer?  There is a physical limit on the trim range where the nozzle pieces make contact, is it close to that in its articulation?  The trim motor should move from full down to full up position in about 5 seconds.  If it is much slower then it may be an electrical issue such as a weak charging system, battery or bad diodes in the trim control circuit.  Is the trim pump reservoir full?  Is there a chance that the reservoir might have been submerged?  Water will make the fluid frothy and it won't hold the force necessary to keep the trim up under throttle.  These units self bleed provided there is enough fluid in the reservoir (almost to the top), the nuts are tight and there is no water in it.  I just realized the word "trim" may confuse newbies here.  On inboard and outboard engines they call the tilting effect "power trim".  These "diverters" are really power trims and use the same hydraulic pumps as inboard and outboard engines.

When all is working right it should resemble this:

Or this:

Engine Mechanical / Electrical / Re: oil on spark plugs
« on: May 29, 2017, 06:02:58 PM »
It probably doesn't make much of a difference, but windage occurs with cranks.  I'm sure that a windage tray and good valve cover baffles helps control oil atomization much more than which hole gets which.  It doesn't cost anything to put the PCV on the other (right) side where there is less oil getting the crap beat out of it, unless it is interfering with the throttle linkage.  There are lots of little seemingly insignificant engine performance tricks that when taken collectively add up to a win.

Engine Mechanical / Electrical / Re: oil on spark plugs
« on: May 29, 2017, 02:42:07 PM »
On a clockwise engine pcv valve goes on the right because oil is slung up on the left side by the crank.  Breather in the back left for cross flow.  This one has an improvised "puke can" detour on the PCV hose.  It is a Craftsman water trap for an air compressor.

Engine Mechanical / Electrical / Re: Drive Line / Vibration
« on: May 09, 2017, 02:29:27 AM »
If the driveline is assembled differently - "out of phase" than it was balanced it will vibrate.  Check out this video on driveline vibrations:

Engine Mechanical / Electrical / Re: Motor oil recommendations!!!
« on: March 23, 2017, 03:55:53 PM »
And the winner is...

Engine Mechanical / Electrical / Re: Grease?
« on: March 17, 2017, 08:50:43 PM »
Mobil1 synthetic.  Great reputation, widely available, and always mentioned in these discussions on jet boat forums.

Engine Mechanical / Electrical / Re: Oil leaking from head
« on: February 16, 2017, 06:54:02 PM »
Make sure it isn't just leaking down from the valve cover / breather if equipped.  If it is oil leaking out the head gasket on a performance engine you are likely on borrowed time.  You can seal it with Permatex black or JB Weld.  Clean it well with brake-clean beforehand.  You of course run the risk of blowing a head gasket leading to more costly repairs.  Maybe a good time to pull the heads and freshen them up.  If you do the grunt work yourself it should cost less than $1,000.

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