Motor Issues, Pulled Plugs and Look Unused?
 

Long story short, after I pulled the boat out of storage, I swapped the jets on my carbs to run a little leaner. I swapped in new plugs as well. Everything went fine, fired the motors on the hose and everything seemed good. Snappy throttle, excellent idle - just as before I swapped jets and plug.

Went out on the boat today, seemed to idle fine out of the marina. Ran it for a bit to ease into it and eventually worked up to 4k rpm and a decent pace. Powered back to the marina seemingly okay. Came in at idle and the port motor turned off. Fired it back up, ran for a few seconds, then died again. Came in on one.

Pulled the plugs:

Starboard
https://i.imgur.com/8uUr38o.jpg

Port
https://i.imgur.com/dxDZQzg.jpg

I pulled all the port plugs and they look the same, basically too clean and like theyve never been fired. The first one I pulled seemed wet with water, as it did not smell like fuel. The motor fires up every time, but now idles rough and sounds very sputtery and wants to die, especially when I bump it into gear. I can rev it up, but seems slow and it just sounds off and vibrates. I checked all spark plug wires, everything is properly seated and connected. I can even pull a few spark plug wires off and see no noticeable difference n idle quality or rev. Oil pressure is good. I didn't have to tools with me to do a compression test. Checked the oil, that looked perfectly clean and no milkshake.

After trouble shooting, an observation is the port motor water temp would not get over ~110 at idle and seems to be dumping more water than the starboard motor. I have a silent choice, and when it closes the valve, there is an abundance of churned water on the port side, more so than starboard.

Any ideas as to whats going on?

That is risky business without a AFR meter, or keep stopping and checking plugs every so many rpms

Brand new plugs and starboard appears to be running rich, and with seeing water on port, you may have detonated and have some damage. Suggest compression test

In order to do a plug color test you use used plugs and run the engine at the RPM you want for a couple of minutes and pop it into neutral and shut it off right away. don't idle at all. Pull the plugs and check the color.
sounds to me like you may have damaged your engine.
Also understand that you can melt pistons at just about any RPM besides idle.
I melted pistons before at cruise RPM (3500)
There is more to changing your mixture with a carb than changing jets.
The idle screws set mixture even after the throttle is cracked open.
The main jets are mostly for midrange on up but are not the main fuel flow at wide open throttle.
The power valves are for any time the engine is under heavy load. ( getting on plane and wide open throttle)
And there are many other adjustments that can me made.

That's a huge swing. I'm surprised I don't see aluminum on them. You did this without AFR's? What carbs are on them? Have you confirmed what original carb jetting is?

That was a drastic change in jetting on the secondary side.
did you ever run the engine at above cruise speeds?

dumb question but does this boat have one fuel tank or two? if they are pulling off different tanks you could have a lot of water in the tank as you said they looked like they had water on them.

Quick video I took of both motors idling with the silent choice "on" to keep things quiet. Note the water churning behind the port motor.

That's what I was looking for, you did your due diligence.

Head gasket

or burned a valve

I try and do as much research as possible before making changes. In a previous thread, comments were made that the motors were likely extremely rich with my previous jetting. Constantly checking the plugs last season, it confirmed most peoples thoughts. Having not wanting to change anything last season in regards to jetting, I waited until winter "break" to look into it further.

Based on the Holley factory jetting, HP500 jetting, and a lot of other peoples' builds (502s, HP500s, 540s, etc) lead me to jet down to the 79 primary and 89 secondary. Again, today was more of a test and tune anyway, and was just a first season check and I was not hard on the boat.

I monitored all gauges throughout running the boat and nothing was out of whack.

All plugs are the same and what come recommended for the DART heads. Plugs were gapped 0.040, which was the same as the plugs that were in it before. Same model and everything, just new.

Port eng plugs appear to be steam cleaned. Looks like water is getting in from somewhere. Have you cranked it over with plugs out to see if water shoots out any of the holes? Need compression test results.

I believe you have a bad head gasket or leaking header/exhaust manifold.

Misfires/ no fires will cause exhaust water reversion.

Those plugs are not only real cold but also non resistor.

BTW: What kind of ignition and what inital and total timing ...since we are discussing things. :)

Okay...back to the carbs...Any chance a piece of gasket remained in a fuel bowl or you installed a wrong meter body gasket or a jet fell out ? :) lol

Do all 8 plugs appear to be "steam cleaned" to the same degree? If so, I would take a fuel sample before messing with anything else. How long was it in storage? Fuel stabilizer used? Have you added fresh fuel? Replace fuel/water separator lately? If you're running ethanol laced gas like most of us, that stuff attracts water like a magnet.
The fact that you have 2 fuel tanks and I assume each eng feeds from it's own tank makes me more suspicious.

I pulled 5 plugs at random, 3 from the port side port motor and 2 from the starboard side port motor. All appeared to be too clean. To confirm any suspicion, I pulled one from the starboard motor, and it looked rich but definitely firing.

Im going to pull all the plugs this weekend and do a compression test, but I assume all 8 will look clean at this point.

As for storage, it went in in October and came out earlier this month. It went in with low fuel left in the tanks and was winterized and stabil was added. Prior to going out on the water, I filled up both tanks with 93 (~100 gallons each)., so if there was any water/condensation, Im assuming it would be very diluted. Plus, the boat fired up on both motors, on the hose, with no issues after I swapped the jets and plugs on the old remaining fuel. Both idled and ran fine. It ran fine all day on the water until I came into the marina at idle, then it was obvious something was off with the port motor.

I'm not liking the bubbles/water coming out of the port motor. I'm trying to understand the logic in that or why that is.

Here's a pic as I just left the ramp;
https://i.imgur.com/deqo9xD.jpg

Sounds like you got the fuel covered. I've seen single or even multiple cyls get steam cleaned when an intake or head gasket leaks but hard to imagine how all 8 could look the same. :food-smiley-007:

Did you come off plane fast and take some water up the tail pipes? seen it happen numerous times...just a thought??

Update: Went down to the boat

Brief synopsis/symptoms: Compression is 158-160 all cylinders. No water/milkshake on dipstick, but precipitation/water on valve cover oil fill cap. Second plugs in (on both sides of motor) appear to have more water drops than others. Other plugs starting to actually have some color to them, but still not like starboard motor plugs. Port motor does NOT get past 130 degrees, no matter how long I idle/rev. Starboard motor locks in ~150. Oil Pressure is good. A lot of tiny little bubbles coming out of port motor exhaust when silent choice on. Vacuum is all over the place even though "idle" seems steady rpm. Distributor cap and rotor appear very clean and excellent shape.

Pics of plugs in order from front to back on port side:

https://i.imgur.com/eGyUofD.jpg

https://i.imgur.com/uwvcBDD.jpg

https://i.imgur.com/aR25DbB.jpg

https://i.imgur.com/lKqhMwg.jpg

Dip Stick:
https://i.imgur.com/iePw3KB.jpg

Port motor fill cap:

https://i.imgur.com/PzOKy6v.jpg

Port motor/starboard side, 2nd bank from front plug:

https://i.imgur.com/CVAvIHr.jpg

General gauge info:
https://i.imgur.com/AfmJ7BM.jpg

Videos:


High Idle/Silent Choice ON

Both Motors on, turn of starboard motor ~30 second mark

Silent Choice Off

Vacuum Gauge

Bouncing vacuum tells me work valve guides

Eeeww, that's not good. Definite intake valve issue. What's the intake vac look like on the other eng?

IMO you have a leaking head gasket.

Looked back for history in case there was some and found it. Here is a refresher for everyone on awol's engines/boat, and performance last year when it was new to him:

https://www.offshoreonly.com/forums/...-attached.html

Please read it so you/we can get a better understanding of it all.

Note for those after reading that and involved with that last year:

It is not just a basic rebuild
It does not have a 'like' HP500 cam and etc
It has a 230/236 .598/.610 114LSA Crane cam.
The HP500 had the 721 which was 222/230 at .050" 110 LSA cam.
The Hp500 had GM cast iron heads upgraded from 2.19/1.88 valves to 2.25/1.88 valves. the OP has Dart heads. Which ? I don't know. The part# on his build sheet is for Dart Iron Eagle small block heads. So that's wrong of course.
The HP500 has a Dart 4150intake. The OP's has a newer designed Weiand 4150 singleplane intake.
The HP500 cae with Gill exhaust manifolds/risers. The OP's seems to have Stainless Marine exhaust. I don't know if dry or not.

The OP got 89+mph out of his 33 PowerPlay with his engine's. Def faster than stock HP500's !

BTW, beautiful boat Awol !!!

Vacuum is rock steady on the other motor.

SB has the link to my progress on the boat since I bought it. It's come a long way. 89 was it's best last year, it's usually an 87 mph boat. I was hoping for 90 this year.

As far as the current dilemma, I've tapped out and contacted a shop and will be bringing the boat in this week. He's a week out, so I'm thinking I wont get any info until 2 weeks or so. I'd love for it to be an intake manifold gasket leak or something simple, which would cause a misfire and vacuum fluctuation. The compression being solid across the board has me doubting a head gasket, but you never know.

If its something really serious, I may bail on this season and work up some blower motors and get this thing running 100+.

If you have any more ideas, Im all game. At the very least, I'll update this thread if a diagnosis/repair is reached.

The intake vacuum jumping around (seems a bit low too) plus passing the compression test makes me think that one or more of the intake valves are intermittently sticking open. At cranking speed , the valve/s may be un-sticking fast enough but when running it doesn't close in time.

Another possibility would be lifter problems or improper valve lash adj. I would try adjusting the valves paying particular attention to how much the adjusters need to be backed off before they start to tap (assuming hyd lifters) . On a SBC, tapping should start at 1/2 to 3/4 of a turn. Not sure if big blocks are different. This may be more than you want to get into but thought I would throw it out there.

it could be valves adjusted to tight,that can cause water reversion because the exhaust valve doe,s not close all the way.even if only one exhaust valve is set to tight a small amount of reversion can happen.

water reversion is easy to figure out - if you have risers and manifolds pull ur risers off and look for water and or rust in the exhaust portion down in the exhaust manifolds - especially at the lowest exhaust portion of the manifolds. With reversion the spark plugs should show some water on them or rust itself. Also with plugs out crank over the engine and see if water comes out - before doing this disable the ignition for NO spark.

If you have headers / NO risers pull them off and look for water in the exhaust portion and in the exhaust ports of the heads. Rust will be in the exhaust ports of the heads (cast iron heads ) and will be able to see whats on the exhaust valve stems as well. rust / pits or carbon or whatever

I cranked the motor over without the plugs (and ignition coil pulled) and no water came out.

Agreed, and If adjusted too tight they will only get tighter over time.