Engine Carnage

[bobcowan]

I went to the track today to get some seat time, and test some new suspenions settings.

The first 45 minutes were awesome. The weather was perfect, the track was fast, and the car was just smokin' fast. When you're in the groove, it just feels so good.

Then, all of a sudden, things went south in a hurry. As I came off the back stretch and in to turn 4, the car instantly ran rough, and smoke was coming out the right tail pipe. Dang it. As soon as I could get off the racing line, I pulled it over in the grass. It didn't appear to be leaking anywhere, just steam from the tail pipe.

I turned the keay, and it started right up. It was clearly running on 7 cylinder, but it ran OK. I drive the mile or so back to the pits, and drove it onto the trailer. When I got home, I drove it up onto the lift, and started taking it aparts.

My first clue was these three mystery bits. The two small ones were on the intake manifold. The longer piece was sitting on top of the #4 throttle blade (8 stack EFI).



When I pulled the valve cover off, the #4 valve springs didn;t look right. I pulled the rocker off, and the valve came with it. Uh, oh. That can't be good.



A dropped valve always cause some damage. I had no idea.
One of the valve heads (intake?) is imbedded in the chamber wall. That's an oil ring stretching across the ports.



The piston didn't fare so well, either.


Well, I was planning to rebuild this engine in a couple of months. I still had three races, two club events, and a show or two to attend. This is going to cost more than a simple overhaul. It will take me at least a month to get it running again.

Sigh.

[Excaliber]

Wow, great pics of the carnage. It's OK, you were looking for a good excuse to rebuild anyway sounds like.

[Skuzzy]

That's an ouchy, for sure. A rebuild is one thing, but recovering from a dropped valve is a little more than just a rebuild.

Hate it when that happens.

[Double Venom]

Perfect timing!
Now I can show my wife what she has done to her Mountaineer. I'm just hoping the piston/bore are still OK?

Always something!
Good luck with your re-build!

[mdross1]

Ouch! but it was fun to the end.Once had near the same thing happen to me in a 69 SS Chevelle giving the wife a ride 2 days after I bought the car.Around 4K rpm going into second gear,instantly hit the clutch and key when hearing a loud knock.Too late kicked a rod and ruined a 375hp 396 block.Did save the complete top end

[Snakebit]

What make are the heads? Did the valve lock break and the valve let go? I noticed a cracked valve lock when adjusting the valves and had to replace it! Scary.

[slider701]

Originally Posted by bobcowan

The first 45 minutes were awesome. The weather was perfect, the track was fast, and the car was just smokin' fast. When you're in the groove, it just feels so good.

They always do seem to run the best just before they blow up........

[vector1]

Originally Posted by slider701

They always do seem to run the best just before they blow up........

what i was thinking. i'm always amazed at how pliable metal really is.

[Jerry Clayton]

were you running lash caps on the valve tips??????

I'm thinking you weren't?

[CowtownCobra]

Bob, my condolences, Friday the 13th bit you pretty good.

[vector1]

Originally Posted by Jerry Clayton

were you running lash caps on the valve tips??????

I'm thinking you weren't?

lash caps? please do tell.

[YerDugliness]

I dropped a valve once on an old Ford 312 Y-Block.

The valve destroyed the piston and then ventilated the cylinder....then the rod ventilated the block.

I hope it's repairable, but don't be surprised if you have to sleeve it (or, replace it?).

Dugly

[bobcowan]

I was planning an overhaul in a couple of months. But this will be more extenive. The #4 cylinder will need to be sleeved; we'll see what the others look like. I wouldn't be surprised if the rod is shot, too. I'll have to check the cam carefully. it might have taken a beating on those lobes.

I'll also have to replace the oil cooler and flush the lines, since the cooling pump was on.

The heads are from Dart, and ported by Gordon Levy. They've been in use for 4 years. Although I did replace the springs at the last overhaul. Not sure what I'm going to do about heads, yet.

Lash caps?

[CobraEd]

I dunno, . . . . a little buffing with the Dremel Tool and it will be as good as new


.

[67FEfastback]

x3 on lash caps

I had a dropped valve, years ago. After looking at the valve tips after disassembly, 90% of them were shearing little slivers of metal. This was a function of the valve lift and spring stiffness.

We were able to save the very expensive heads by redoing the valve seats, sleeving the block.

good luck

[madmaxx]

Holy sheeeeeeeet!!! I would have never imagined that much damage. How many miles on the engine. Is it a stroked small block.

[Double Venom]

OK, I'll Bite- "Lash Caps"? Is that like a muffler Bearing?

Certainly you are not talking about the "Keepers"?

[CobraEd]

Originally Posted by Double Venom

OK, I'll Bite- "Lash Caps"? Is that like a muffler Bearing?

Certainly you are not talking about the "Keepers"?

http://www.jegs.com/p/JEGS/JEGS-Valv...24579/10002/-1

.

[olddog]

I do not know if it is an after market block nor how much modifications were in it. My son picked up a running (but low oil pressure) 351W for $50. I'm not sure I would mess with fixing that block. Metal in the oil passages. Possible cracks from the collision of parts. I would think you could have another block ready to assemble for under $1000.

[Jerry Clayton]

Bob

You are lucky that you are running the stack type injection--if for instance you had an 180 degree manifold you would have killed cylinders 1, 6,7 also besides 4 because pieces would have transferred thru the intake to those cylinders--if you had been running an single plane you would have killed them all!!!

Now to answer the lash cap questions---the unit pressure on the rocker tip to valve is the most highly stresses area of a rocker arm engine. All the force to open the valve goes thru the tip of the rocker, and I am sure everyone will agree with that point. Secondly, the total tension load of the valve spring assy is trying to shear off the lock keeper at the valve groove ( what happened here) there are opinions about the strength of the 10* keepers vs 7* keepers as to if the groove holds the load vs the grip that the taper puts on the valve stem holds the load----However you want to see that fact is up to you, however , IF you use valve train componetry that uses lash caps for the rocker tip to operate against, they will push on the keepers which transfers the force to the retainer , which pushes on the valve spring and the valve in its self only sees pressure(force) when its in the area of valve lash!!!!In effect--once the rocker has taken up the valve clearance(lash) the valve is just along for the ride and has no force from the spring acting on it until the valve closes and the cam is in the lash area of the lobe.

Hope that explains it---lash caps have far more important duty than just correcting geometry.

Also---after 45 minutes of fun were you downshifting at too high of a speed and over revving the engine???rev limiters don't work in that situation

Also in addition to cleaning the oil system components, you will need to clean the exhaust on that side because it undoubtible has trash in it now and reversion can reenter the engine thru the exhaust passages