SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Sin City Spectra on March 14, 2011, 12:32:24 AM
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Well guys, I took my Spectra out to Lake Mudd today to see how it survived the winter and had a great time for a couple of hours. i was running about 4500 RPM and i had a pop, bang and all of a sudden 7 cylinders. Got it back to the trailer and took it home, tore it down and found cylinder 6 was missing the exhaust valve, it was broken off at the stem. of course the piston is beat to hell, the head is screwed, rocker arm is worn and wow you should see the spark plug... im looking for some parts, on a budget, maybe a complete motor? Above all im looking for some advice, any ideas what could have happened? I mean the valve head is gone, at the bottom of Lake Meade. So are there any takers? Guesses? My first thoughts are water, but i was underway, so who knows... maybe just the end of that valves life?
Any help would be great,
Mike
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I will toss out my idea, since I have seen it happen to guys before. How old was the gas in the boat?
Yes it's possible the valve was tired, but if you go out with old gasoline and run hard with old gas (maybe it sat 4-5 months?), then you probably had some detonation and heat going on.
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That was my first thought, gas was from about 5 months ago, less than a 1/4 tank in each tank, treated the fuel before i parked it for the winter and filled it with fresh gas before i hit the lake Sunday. all the other pistons and valves look fine, no signs of detonation...
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i ran 1 year old gass through my boat and it was fine. just mixed it with new gas and mix... maybe i was lucky
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That was my first thought, gas was from about 5 months ago, less than a 1/4 tank in each tank, treated the fuel before i parked it for the winter and filled it with fresh gas before i hit the lake Sunday. all the other pistons and valves look fine, no signs of detonation...
Don't know what kind of exhausts you have, but another possibility would be previous exposure to water and rapidly changing temperatures. Was it a "stock" automotive type valve?
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take the opportunity to switch to a bbf or bbc? i hear nothing but problems with the olds motors...
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Does anybody have or have access to an A frame hoist, my cherry picker wont reach over....
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What part of town are you in?
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We are in west Phx,az. and I have a bunch of Olds stuff. Will be in Havasu this weekend too with the truck. TIMINATOR 623-877-8553
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I'm in the south end of town, Warm Springs and 215 area. I found a motor, its a pluck out of an old jet boat. it has Hardin exhaust, water pump plate etc etc... but it has an HEI, thats not normal is it? I dont remember seeing too many boats with HEI's, so i wonder if this was a stock car motor swapped into this boat years ago??? The block cast number is 396021 F, any thoughts?
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That # is 68-76 and is a car block The Fa is a marine block the thing you need to know is why was it pulled out of the boat and does it have a spun bearing ????? I have a Fa block for marine use 30 over forged pistons and a set of Ka marine heads if interested Iam in Havasu 928-846-4709
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I'm in the south end of town, Warm Springs and 215 area. I found a motor, its a pluck out of an old jet boat. it has Hardin exhaust, water pump plate etc etc... but it has an HEI, thats not normal is it? I dont remember seeing too many boats with HEI's, so i wonder if this was a stock car motor swapped into this boat years ago??? The block cast number is 396021 F, any thoughts?
Is that the one out of that old blue boat at the industrial yard off of lake mead and nellis? If so that one looked to be rough. Also, HEI is a good way to go.
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the guy bought the boat, could not get the right paper work for it and pulled it out before scrapping the boat.
i am having some crazy thoughts, someone kick me... im thinking of putting the heads from this new motor onto my short block, i know the piston has some cosmetic damage but i have measured from the deck to the top edge of the piston and compared to the other cylinders, and the rod isnt bent, thats a plus... This way i keep my marine block, forged pistons and i can get back on the water and save my money to buy some parts over the summer and build a new motor next winter, how far fetched does that sound guys?
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the guy bought the boat, could not get the right paper work for it and pulled it out before scrapping the boat.
i am having some crazy thoughts, someone kick me... im thinking of putting the heads from this new motor onto my short block, i know the piston has some cosmetic damage but i have measured from the deck to the top edge of the piston and compared to the other cylinders, and the rod isnt bent, thats a plus... This way i keep my marine block, forged pistons and i can get back on the water and save my money to buy some parts over the summer and build a new motor next winter, how far fetched does that sound guys?
Personally, if you've got it that far down, I'd keep going, pull the block and check everything. Nothing but gaskets, rod nuts and a little more time if all is well. ;)
But it CAN be done your way successfully..............
Ray
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I picked up a set of heads, I'm gonna do a quick lap job, valve seals and put it back together, we will see what happens. I am just gonna start collecting new parts and build a new motor next winter. Still looking for someone who has an A frame or Gantry...