Dropped off my heads on Monday. They were done Thurs. It seems I was not to far from a larger disaster.
Now I'm off to find some exhaust.
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Dropped off my heads on Monday. They were done Thurs. It seems I was not to far from a larger disaster.
Now I'm off to find some exhaust.
Sweet. Back on the water by Memorial [emoji106]
I forgot to add the important things.
Broken valve
Attachment 52923
Newly reworked heads
Attachment 52924
Who you calling slow?Quote:
Originally Posted by Hotboat
That was a close one. It's nice to catch it before catastrophic!
Cool, see you in Parker this weekend [emoji106]Quote:
Originally Posted by Cigalert
You're towing now? :partytime:Quote:
Originally Posted by Hotboat
Never lolQuote:
Originally Posted by Cigalert
OUCHIE!!! that was going to be an ugly one... Can we see a pic of the face of that valve please??? Just for grins you should measure the overall length and compare to some of the other valves that don't show as much of the melt down/stress... :)Quote:
Originally Posted by Cigalert
I would look for a deeper issue/cause... Lean is mean but not tooooo lean... Maybe too much spring for the quality of that particular valve??? Could be a few different things going on... Cool stuff, ty for sharing... ;)
This is from the AERA (engine builders association)
"The two intake valves shown in Figure 2 are both out of the same engine. The one tuliped valve is .220" longer than its original length. This was the result
of an abnormally high combustion chamber operating temperature. This temperature is in the cylinder of the engine, NOT THE ENGINE COOLANT TEMPERATURE. The temperature surrounding the valve got much higher than the valve was ever designed to withstand. That excessive temperature resulted in the valve material softening, allowing the valve head to stretch to create what is called a "tulip" shape.
A normal combustion process operating temperature in the combustion chamber could be considered 2500° F with cylinder pressures between 900-1200 psi. Engine valves will only survive the normal temperatures because they are seated during the combustion process and transfer heat as designed to the head casting.
An abnormal combustion process may increase the operating temperature in the combustion chamber as high as 5000° F with pressures between 3,500 - 5,000 psi. If this "tulip" condition re-occurs after rebuilding of the engine or reconditioning of the cylinder head, the original problem has not been fixed. This condition may affect one or more valves at a time.
Items to check; properly working EGR system, correct ignition timing, ECU operation, vacuum leaks (intake manifold, hoses, etc.), correct air to fuel mixture, correct angles between the valve and the valve seat, excessive valve spring pressure and any other source that affects the combustion process.
The AERA Technical Committee"
I don't have a pic right now but lost the electrode from #6 spark plug. One theory is electrode got swatted and hung up on this exhaust valve. As the valve was returning to seat it decided to flower inward with the electrode as a pry bar. No pitting on piston head or valve.Quote:
Originally Posted by 2manymustangs
My idea would be a little different, look at the other plugs and check the color/condition/age... I dont know BBC engines and which holes run hotter but it could be that either from age/detonation/bad plug it could have melted but your REAL lucky you noticed or took action when you did...Quote:
Originally Posted by Cigalert
If that particular hole runs hotter in a BBC, you could be on the ragged edge with your A/F - temps...
I would dig deeper, I'm pretty sure that if the electrode broke away and blocked the valve it would have left some evidence behind on it's way out of the hole but I may be wrong, if it was one hit and gone... Hard to say but the plugs are a real good way to draw a conclusion of what led to this...
Good catch, your damn lucky :) THEN AGAIN, if you were looking for an excuse to build a bigger/badER mill, try a little harder... :D
I'm already waiting for my 429CJ to fail so I have an excuse to bump it up to 540 inches and really utilize the CJ heads if they survive...
Maybe the MILLER (Buzz/Paul/TheDr.) klan could lend some free advise here as to which hole gets hot in a BBC or what they have experienced over the decades of blowing things up / A-F / melting plugs / etc... :)
Some additional information....motor is 25 years old, either the riser or the exhaust manifold (or both) are bad/leaking, allowing water into the piston, compression of water knocked out the plug, upon exit/down stroke hung up valve. BTW, the electrode was found after pulling starboard exhaust. And really, no evidence of damage. To internals. And since I wasn't there for the machining rebuild process I cannot comment about any damage/pitting to the head/seat of that exhaust port.
:thumb: so maybe the messed up valve was the expansion valve when you tried to compress the water... ;)Quote:
Originally Posted by Cigalert