I pulled my heads on my 23gdsd last year to install worked heads. When i took the heads off and inspected the cylinder, i noticed some pretty heavy pitting (wear, ect) towards the bottom of one cylinder, and light pitting at the top of the other. I think they were caused from rust from the previous owner. I spoke to a mechanic and he said if it isn't smoking/burning oil then its fine as is.

Here recently, i've noticed my motor has been progressively lacking the umph with a load. Last weekend i was running and motor died. Re-started and i couldn't get past 3000 rpm with prop in water. Will rev to limiter with prop out of water. I noticed exhaust was getting red hot. Acted like it wanted to seize. Let it cool down and it ran until it got hot again. limped home. I pumped bulb while running, no change.

Do yall think any of my issues are stemming from the cylinder wall damage (losing compression)?

Ordered a leak down tester, waiting on that to arrive.

FWIW, have a mikuni carb and BPS exhaust. mods were added approx 30hours ago. Carb was tuned with afr meter, so I do not think its a jetting issue.

I'm hoping it's just the pictures being misleading, but the crosshatching doesnt look very crosshatchy. See what the leakdown test shows, then report back.

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The rings are hurt no doubt, but a sudden drop and power loss I'm thinking vacuum leak, floating valve, piece of trash in main,,,,, Its also common to chunk parts off the stock cam like compression release arm

What are my options as far as repairing the cylinder and rings? I’m assuming it won’t be good for overall engine health to keep running like that?

I’m going to dive into it this weekend and clean the carb, check the plugs for fire/fouling, valve lash and push rods condition. Spray some carb cleaner around my mating faces to look for vacuum leaks. I’ll then get some leakdown readings. Anything else good to check?

Is doing a leakdown just at TDC sufficient?

Any way to check cam condition without splitting the block?

Measure the lift.

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Easiest to press the rockers down and release the pushrods to do leakdown on the smallblock Leave pushrods in their respective positions. To rebuild it it will need to be bored .020 over. New pistons from Briggs comes with new rods now and are cheap. Under I can't think of a way to innspect that arm without popping the cover.

Will probably knows the specs. I would just compare. If its real bad, you may be able to see with your naked eye. Can probably measure with a caliper though and be pretty close, unless you have a degree wheel/cam timing kit.

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Just make sure they all dip the same.

Got to do some digging last night.
-Plugs looked good, a little sooty like they are a hair rich. #2 cyl plug looked a tad wet but only at the bend on the ground strap.
-Push rods were in good condition.
-Leakdown was performed at BDC because i didnt have a good way to keep engine turning over.
I feel like the leak down numbers are decent for the cyl damage i see. Both cylinders leaking through exhaust valve and through the crank.
-Valve lash was out slightly, would a couple thousandths really make a big difference here?
-Cam lift numbers listed below. they were taken with calipers, from top of retainer to the valve cover gasket face. Thinking ill probably borrow an indicator from work tomorrow to verify those numbers. yall see any red flags here?
-Cleaned the jets real good. Need to take off the plastics to check for vacuum leak around the manifold/head still. Once i do that, i guess ill go run it with clean jets and see if that was the issue. Boat did sit up for about 5 weeks before my issues.
-Note: #2 cylinder exhaust header is the one that kept getting red hot the quickest

Plug color is useless for anything other than idle analysis unless done after an extended run at full throttle and cutting off without any idle time.

Pull the pushrods then do another leakdown test to keep the valves from being a questionable item. Also, keeping the engine from turning over is as simple as a screwdriver in the teeth of the flywheel or using a board to keep the prop from turning (since a gdsd doesnt have neutral). Dont halfass the tests, but if you're comfortable with it being a carb issue, good luck.

#CFFITR
#GhostBoat
#Whoneedsphysicsihaveamudmotor

Btw, no, valve lash was close enough to not be causing the issues you've described, but keep them at spec when its adjustment time.

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#GhostBoat
#Whoneedsphysicsihaveamudmotor

I did do the leakdown with the pushrods out. Ill go back and do it this week with push rods out at tdc and see if i get any different numbers.

Probably not different enough to explain the issue. More likely a vacuum leak causing it to run lean.

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#GhostBoat
#Whoneedsphysicsihaveamudmotor

Checked lift again with a mag base indicator today. Looked a lot closer. Both intake valves opened a total of .307”, one exhaust opened .280 and the other was at .288”.

Leak down on cylinder #2 was at 24% at TDC. Pretty substantial drop there. Cylinder #1 was unchanged between TDC and BDC.

Found a small vacuum leak between the carb and intake boot. What do y’all do to seal up this area? The clamp is already tightened as far as it’ll go.

I did notice something interesting with the indicator on the valves. The intake valve would close, the exhaust valve would open .010-.015, exhaust would close, then the exhaust would open again the full amount of lift. that does not seem right to me with the little I know about cam lobes and base circles. This was happening on both cylinders. I can upload a video of this if what I’m saying isn’t clear.

After a little reasearch, the exhaust valve double lift is the compression release feature for the pull start. Shoulda figured that one out sooner.

any ideas on how to fix the leak between the rubber boot and the carb? as i mentioned the band is already all the way tight and its still leaking on one side. Running a bead of gasket maker is my only thought other than trying a new boot.

I always put a bead of rtv in between the carb boot and intake.

Yeah i have rtv between the boot and intake but my issue is between the carb and boot. Boot has the lip inside to ride in the groove of the carb, but its still leaking around those two pieces.

Could be as simple as cleaning the crust out of main jet on cyl2