Broken Valve Broke, Piston damage what should I do?

[Hydro-Thunder]

Heres the deal with this. I was out on the lake and all of the sudden the engine started to miss really bad no noise just missing so I shut it down right away and got a tow back to shore. I started to pull plugs and I found #4 was pounded up pretty bad so I pull the head off and found a valve head broken off. It has slapped the piston but there are only dents in the top of it. The cylinder walls look fine. Heres the question do I dare smooth out the top of the piston and run it the rest of the year or will the weight difference from the removed material cause problems? I'm sure I should pull the engine and replace the piston but am looking for a short cut at this point. Do I dare do something like this. I will post pictures tomorrow.
BBF 460 60 over with flat tops
Jesse

[Fiat48]

The weight removed from smoothing the sharp dings in the piston won't cause any problems. Kinda the least of your worrys. You need to determine why the valve broke.

[Dave C]

why wouldn't you take it apart and check for cracks at this point?
Sounds like this could get catastrophic?

[tbanzer]

I would pull that piston out and inspect it. Most likely the top ring land is pounded down enough that the ring will stick in the piston. Probable time to replace all valves and springs.

[SoggyJet]

I have done what you are talking about in a LOW performance boat in my past. I replaced the valve and put her back together. It ran fine for years, but when I finally took it apart to freshen it up I found that it had crushed the ring land slightly and the ring was stuck in the groove. Bottom line it is not the best way to repair, but it may get you back on the water without loosing the rest of the season. If you go this route, just take it easy and fix it right in the off season.
Doug

[Hydro-Thunder]

Thanks I knew I would have to pull it again but did not want to do it now.
Jesse

[Hydro-Thunder]

This is kind of for Fiat48. What kind of things can make a valve break? I was thinking that it could have been from running it hard that day but there are some small pits in the intake valve also so some Detonation taking place? What else should I check?
Jesse

[Hydro-Thunder]

Still looking for help. What would cause a valve to break?

[Squirtin Thunder]

I have had brand new valves break. Valves break in cup all the time well some times for absolutly no real good reason. So WTF fix it and get it wet.
Jim

[GofastRacer]

You need to use the best parts for your application, anything less will burn ya down the road. :rolleyes:

[SoggyJet]

Things that will make a valve break:
1) material defect - small void or impurity inside the stem causes stress point and eventually cause failure. the defect is invisible unless you do expensive tests like x-ray, even then it can be missed
2) improper clearance on valve guide, valve hangs out and gets hit by piston - usually bends sometimes breaks
3) rust on valve stem, causes valve to hang open gets hit by piston- usually bends sometimes breaks
4) over rev engine, valves float and get hit by piston - usually affects more than one valve - usually bends sometimes breaks
5) broken or bad valve spring(s) - valve doesn't close and gets hit by piston - usually bends sometimes breaks
etc
Doug

[Fiat48]

What he said. Or just old age valves or cheap valves. They gotta live in unbelievable heat, especially an exhaust valve. Retarded ignition timing makes exhaust valves run much hotter also.

[Hydro-Thunder]

Thanks I thought there might have been more to it than that.
Thanks Jesse

[cook1]

Are your heads and valves stock or are they after market. I just broke a valve on a set of alum edelbrock heads{second time}. Don't know what to do now.

[chriscraftstinger222]

I just broke(cracked with small chip missing on edge) an intake valve on my SBC and have still not yet been able to determine why. The heads were freshly rebuilt with less than 50 hours and there is no damage on on the piston top. The engine ran very strong except for sluggish throttle response from idle to 1500 rpm. I'm hoping the broken valve had something to do with my poor throttle response. But now I'm stuck trying to figure out why this valve broke. The engine was timed at 36deg total advance and the plugs did not indicate a fuel shortage. The valves were GM parts. We'll see what the local engine builder has to say. I hate to think about putting this engine back together and not knowing what caused this problem. By the way, what is the trick to adding a picture to my posts? Everytime I try to attach a file it does not load. Thanks-Will

[AZKC]

Hey I 've been down this road before
http://www.***boat.com/image_center/data/504/57email_pics0002-med.jpg
http://www.***boat.com/image_center/data/504/57again0013-med.jpg
:eek:

[chriscraftstinger222]

Bingo! I found the problem. I had to look real hard but there it was staring me in the face. Upon close inspection of the piston top I noticed a small mark where the valve hit the piston. I had to clean a little carbon away to see it clearly as it is very small and almost unnoticable. This leads me to believe that it may have occured early post-rebuild since it was underneath the light layer of carbon. Looks like this cracked valve may indeed be the cause of my sluggish throttle response. It might have even occured before I purchased the boat when the previous owner was breaking in the motor. Based on the fact that the distributor cap was not seated properly-I wouldn't hesitate to think that it's possible the previous owner might have mistakenly advanced the motor too much. In any event, I plan to have the valve spring checked and the valve replaced if the heads come back with a clean bill of health. The question now is how did water get into my oil? I'm hoping I don't have to buy new heads but on the other hand I'm always looking for a good excuse to improve performance.
http://www.***boat.com/image_center/showphoto.php?photo=47738&password=&sort=7&thecat=500