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Cyl 3 spark plug came appart.
Cruising at 3500rpm and boom. Turned the key off and the engine was still trying to run. Bbc 509cid.
https://cimg6.ibsrv.net/gimg/www.off...67c2e90db4.jpg https://cimg7.ibsrv.net/gimg/www.off...2ac1785f78.jpg https://cimg9.ibsrv.net/gimg/www.off...378351bca1.jpg https://cimg2.ibsrv.net/gimg/www.off...a60a878786.jpg |
check your timing, had same issue happen to me......preignition that i couldn't hear
in my case my distributor loosened and one tight wire pulled it counterclockwise best . |
The plug boot has seen better days, might have been arching a bunch
As clean as the ground side electrode is it looks like it was running lean. Might want to use a bore scope and check the piston |
Originally Posted by AllDodge
(Post 4846080)
The plug boot has seen better days, might have been arching a bunch
As clean as the ground side electrode is it looks like it was running lean. Might want to use a bore scope and check the piston |
Originally Posted by SammyJ
(Post 4846079)
check your timing, had same issue happen to me......preignition that i couldn't hear
in my case my distributor loosened and one tight wire pulled it counterclockwise best . |
Plugs blowing out like that does happen more than you think. I've had it happen once years ago
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Originally Posted by Griff
(Post 4846109)
Plugs blowing out like that does happen more than you think. I've had it happen once years ago
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What delco plug # you using ?
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Originally Posted by SB
(Post 4846122)
What delco plug # you using ?
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Ok, the cyl 3 has 10bar compression, wich is 3bar less compared to other cylinders (13bar). Made leakdown test that measured 90%(cold engine) and got more confused, pressure seems to go in intake manifold, exhaust manifold and crakcase. Conclusion is that intake/exhaust valves are leaking, not sure about the piston rings because the large ring end caps and piston to wall clearance, due 2680 forged pistons. Took some pictures of the exhaust ports/valves/spark plugs. Removed the cmi sound eliminator mufflers, wonder if the mufflers caused reversion and caused all this. Other one of those mufflers feels tight compared to the other one. Dont know 🤥🤥
https://cimg7.ibsrv.net/gimg/www.off...c880c74146.jpg Cyl 3 https://cimg0.ibsrv.net/gimg/www.off...1dd456581d.jpg Others https://cimg4.ibsrv.net/gimg/www.off...2ba4620156.jpg https://cimg5.ibsrv.net/gimg/www.off...fb12451f5d.jpg https://cimg7.ibsrv.net/gimg/www.off...e67cc57873.jpg https://cimg8.ibsrv.net/gimg/www.off...1129eb9b54.jpg https://cimg9.ibsrv.net/gimg/www.off...a8b349494f.jpg https://cimg0.ibsrv.net/gimg/www.off...05369ee0ce.jpg https://cimg1.ibsrv.net/gimg/www.off...23dfcae57b.jpg https://cimg2.ibsrv.net/gimg/www.off...18291ea95c.jpg https://cimg5.ibsrv.net/gimg/www.off...53e4c4e2b6.jpg |
In the mid 90's a buddy of mine bought a drag sled, thinking he could trail ride it. If he tried to run just plain premium gas, every time he would let off the throttle from a wide open run it would blow the porcelain out of both plugs, if he ran 110 it would not happen. The few rides we went on prior to reducing the cr required pockets full of new plugs.
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There is a hole lot of white on those plugs
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Originally Posted by JaniH
(Post 4846891)
Ok, the cyl 3 has 10bar compression, wich is 3bar less compared to other cylinders (13bar). Made leakdown test that measured 90%(cold engine) and got more confused.
10 bar = 145psi 13 bar = 188.5 psi |
Originally Posted by SB
(Post 4847085)
Just converting bar into soomething we understand so we can follow.
10 bar = 145psi 13 bar = 188.5 psi |
delete
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Originally Posted by AllDodge
(Post 4847084)
There is a hole lot of white on those plugs
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Originally Posted by resurrected
(Post 4847079)
In the mid 90's a buddy of mine bought a drag sled, thinking he could trail ride it. If he tried to run just plain premium gas, every time he would let off the throttle from a wide open run it would blow the porcelain out of both plugs, if he ran 110 it would not happen. The few rides we went on prior to reducing the cr required pockets full of new plugs.
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https://cimg7.ibsrv.net/gimg/www.off...add533e1e9.jpg
Engine is out of the boat. Very curious what i find when i bull the head of. |
1 Attachment(s)
#1 and #7 look just very slightly on the rich side, but okay. Rest look good. The white on the porcelain is olay also. The porcelain can be one indicator of the correct (or incorrect) heat range of the plug. Jmo.
here's one article that explains some things. There's another i am trying to find that I've seen before that explains things pretty good as well. http://www.4secondsflat.com/Spark_plug_reading.html Attachment 577414 |
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Originally Posted by Cap'm Kurt
(Post 4847182)
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Pulled the intake of today, lots of moisture below the intake. Oil in the dipstick is clear and so is the oil laying in cylinder heads, valve cover breathers are very creamy also. Could be normal taking to account that weather is cold here in this time of the year, looking at the exhaust valves, in the two center ports of both sides, the valves looks much brigther, and those ofcourse are just below the riser. I am arrraid that those cmi muflers may have related to this. I definetly have to dismantle the mufflers and check the spring tension adjustment. I try to pull the cylinder head of during this week.
https://cimg7.ibsrv.net/gimg/www.off...d50bf5479d.jpg https://cimg9.ibsrv.net/gimg/www.off...85d8bceed1.jpg |
The sludge. Probably reversion, reversion, reversion (moisture backing up in pulses thru the exhaust when idling, and yes while it is running). There's a million articles on this topic all over the internet and here on OSO. i even wrote one a couple years ago. Only way i completely solved it was to weld on 3" diameter alum extensions to the elbows( I use Eddie marine). I kept welding on 6" at a time until i reached 25". Only then did it stop alltogether. Talk about a difference. The oil looked so much better. And didn't smell as acidic. Also angle cut the tips of the 3" extensions. I'll see if i have pics. Other friends with bigger cams had to go about 5 more inches to get it to stop.
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Look in your exhaust soon as you pull it out of the water. If it looks like this. Reversion.
https://cimg1.ibsrv.net/gimg/www.off...0a06779344.jpg https://cimg2.ibsrv.net/gimg/www.off...2eeb282b9e.jpg |
I went to +3 elbows on my Eddie Marine exhaust and have no issue with reversion (509 dyno 530hp), and I'm using turn downs
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These resonators will stop the reversion also, but i didn't want the restriction.
https://cimg4.ibsrv.net/gimg/www.off...f294f76dc8.jpg |
picture of the 3 inch aluminum exhaust extensions to prevent reversion
https://cimg6.ibsrv.net/gimg/www.off...a53ab4815b.jpg |
Originally Posted by Cap'm Kurt
(Post 4847304)
picture of the 3 inch aluminum exhaust extensions to prevent reversion
https://cimg6.ibsrv.net/gimg/www.off...a53ab4815b.jpg This what I was talking about. They are 3 inch higher then stock and water doesn't come out until end of tube https://www.eddiemarine.com/shop/exh...risers-emi-552 |
Originally Posted by JaniH
(Post 4847285)
Pulled the intake of today, lots of moisture below the intake. Oil in the dipstick is clear and so is the oil laying in cylinder heads, valve cover breathers are very creamy also. Could be normal taking to account that weather is cold here in this time of the year, looking at the exhaust valves, in the two center ports of both sides, the valves looks much brigther, and those ofcourse are just below the riser. I am arrraid that those cmi muflers may have related to this. I definetly have to dismantle the mufflers and check the spring tension adjustment. I try to pull the cylinder head of during this week.
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Originally Posted by SB
(Post 4847321)
Maybe a head bolt or stud leaking water ? Or valve guide ? Or intake gasket ? An actual pcv can help if there are no leaks, but i suspect one..
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Originally Posted by Cap'm Kurt
(Post 4847296)
The sludge. Probably reversion, reversion, reversion (moisture backing up in pulses thru the exhaust when idling, and yes while it is running). There's a million articles on this topic all over the internet and here on OSO. i even wrote one a couple years ago. Only way i completely solved it was to weld on 3" diameter alum extensions to the elbows( I use Eddie marine). I kept welding on 6" at a time until i reached 25". Only then did it stop alltogether. Talk about a difference. The oil looked so much better. And didn't smell as acidic. Also angle cut the tips of the 3" extensions. I'll see if i have pics. Other friends with bigger cams had to go about 5 more inches to get it to stop.
https://cimg5.ibsrv.net/gimg/www.off...87451bbf6e.jpg https://cimg7.ibsrv.net/gimg/www.off...8e920f1716.jpg |
Originally Posted by JaniH
(Post 4847334)
New gen6 502 block, head bolt holes should be blind. What i did notice, is that i forgot to use any sealant in the cylinder head side of the intake gaskets around the coooling passages, but there was permatex in the intake side of the gaskets. Damn!
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Those pics of my elbow extensions where not the final version., but shows the general layout. ended u with 25.5 inches with a 60 deg angle cut.
The regular alum Eddie Marine added 3 to 4 inches height over stock. Which made did NOT stop the reversion. Reversion is a result of pulses of exhaust, not from water just being able to go up a pipe that doesn't have much slope. A bigger slope might help keep a slug of water from coming in from a wave a little better. but as far as reversion, no does NOT stop it. It purely took a certain amount of 3 inch exhaust pipe length to solve it. Nothing else did, and the 25" inches or so of 3" inch extension took it away 100 %.. You can see the reversion(salt specs) up to the beginning of the elbow now but NONE get inside the elbow. Saved the exhaust valves from short certain death, which had occurred frequently before. Hope this info helps, I've spent 100 to 15 hours building and testing with the exhaust to get the reversion stopped. It was continuously costing me valve trains. Many people think motors are "normal" to rebuild every few years. They should last much longer. It's always water leaks, REVERSION, detonation from running regular when you should be running premium, bad gas, enthanol, water in gas, overproped, etc. that gets you. Motors should last a long time. |
Originally Posted by JaniH
(Post 4847334)
New gen6 502 block, head bolt holes should be blind. What i did notice, is that i forgot to use any sealant in the cylinder head side of the intake gaskets around the coooling passages, but there was permatex in the intake side of the gaskets. Damn!
Side note. I see your intake has an exhaust crossover. If you have electric choke, look for blocked (with steel) exhaust crossover intake gaskets. Will get you a little more hp. It’s just something i do because my opinion. If heated choke (rod and spring on intake) i get blocked off gaskets and drill one with a 1/2” hole or so. |
Originally Posted by Cap'm Kurt
(Post 4847304)
picture of the 3 inch aluminum exhaust extensions to prevent reversion
https://cimg6.ibsrv.net/gimg/www.off...a53ab4815b.jpg |
Cheech, yes, from the elbow to the 4" exhaust tips at the transom.
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Originally Posted by cheech
(Post 4847604)
Are you then running rubber exhaust hose over this setup?
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6 Attachment(s)
Any of you guys try running a small crossover pipe/tube to prevent reversion ?
My 2007 VP 8.1 has silly-tall risers, Corsa Captains call and a 1-1/4" crossover hose between them to stop reversion. |
New season, switched to ngk br6fs. made 10min pull at 3000rpm and turned ignition off at 3000rpm. innovate dlg-1 was reading 10.3 while cruising. This makes no sense.
https://cimg1.ibsrv.net/gimg/www.off...006a179deb.jpg |
The Swedish 7.4L engine mod thread by "jocke" got me thinking about Jani and his engine ordeal.
I can't believe everyone missed or ignored this post. Jani - What is this picture? Another blown out spark plug issue like last year? Is your boat up and running? |
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