poop

[tim]

Poop-or something along those lines says it all

[cory]

Poop-or something along those lines says it all

Tim
Don't feel bad. Your chambers look great. That broken seat is not a big deal. Go to Toms restoration diary and look up the date 2/5/13. Those are my heads. I think you will feel a little better after seeing that posting of before and after. My stomach was in a knot when I pulled those heads off and saw that mess!
Good luck
Cory

[tyang]

Hi Tim,

Sorry about the valve seat. I hope that little chunk didn't cause too much damage. How was compression and oil consumption on the engine before this failure? Is it rebuild time?

Tom

[tim]

Greetings… Fortunately just some minor pockmarking in the chamber and piston. I heard a rattle not to far from home. Didn't sound like valve train - a regular tap tap tap - but like something rattling around in a can. I thought maybe a pebble in the bell housing. As I pulled into the garage, it sounded like it had a miss. Found a noticeable irregularity in exhaust. Out came the compression tester and I found #'s 9 and 10 not participating. All the others were 155 to 165 psi. A leak down showed 100% back through the intake. Poop. Off came the head and you see the result.

Now the curiosity. There is no apparent damage to #9 but it had zero compression. It shows a little damage from something rattling around but the seats and valves all look ok. ??? Could part of the broken seat have gone back up the intake port and down the next one?

The car had been running beautifully after fixing a carburation issue. The needle and seats were stuck and it caused a very lean condition. After replacing them, it ran . I had it a Concorso and had been to a number of "cars and coffee" type events. No smoke, no overheating. Oil consumption was maybe 1 qt/1000 miles - I think it leaked more than it burned.

So the big question--- Howcumizit seats break? These had been replaced when I did the engine maybe 30k ago. The reason for going into the engine at that time was a broken seat but different cylinder.

Tim

[cory]

Tim,
Just curious, did you get a chance to drain the oil or even drop the oil pan. It would be interesting to see if anything else ended up in the bottom of the pan.
Cory

[tim]

Hi Cory…
I will be draining the oil and removing the sump but primarily to deal with some leaks but as the pistons are intact, I don't see a way for anything to have dropped there. The investigation continues. Still trying to figure out why broken valve seats seem to happen to our Ferraris.

Tim

[DWR46]

It is very common for pieces from one cylinder to go up into the manifold and back down to another cylinder on that manifold.

[tim]

Greetings.. Thanks for that info. Seem weird but that is the only way I could see it happening. Question remains, though, as to why the seats break,

Tim

[tyang]

Greetings.. Thanks for that info. Seem weird but that is the only way I could see it happening. Question remains, though, as to why the seats break,

Tim

Hi Tim,

I know dropped valve seats can happen from overheating the head, allowing the interference fit to fail. Perhaps your running lean caused this to happen, and the seat shifted and then fractured when the valve closed on the seat? I would take a close look at the adjacent cylinder with the 0 compression numbers and see why that intake valve is not sealing. Flip the head over, install the corresponding intake valve, and look at the fit of the valve seat. Is there damage from debris? You may see the seat has moved slightly out of position. If it's not visibly noticeable, machinist blue will show how the seat seals to the seat.

Tom

[DWR46]

Over the years, I have seen a pattern develop. However, I do not know what it means. Most of the dropped or failed valve seats have occured in engines in the 3000-6000 serial number range. This would be about 1962-1964 production, both with 250 and 330 motors. I know that other V-12's have experienced similar failures, but there must have been something in the assembly techniques used in this period that contributed to the failures over the years.

[Jimmyr]

The observation by Dyke were confirmed with my conversations with Bob Wallace. He noted that multiple valve jobs or cutting too much material from the seats tended to weaken them

[cory]

I would be curious to hear if this has happened to others with replacement seats.
Tim, 30k ago where your seats replaced or originals reworked?
I have had this experience with motorcycle heads from this era. The cause was poor head castings. This I wouldn't necessarily expect from Ferrari as I have heard that the material used in their foundries was very good.
Cory

[tim]

Greetings… Seats were replaced. One of the originals broke so we thought it best to replace them all. My concern is that there is a problem with the installation. I've only pulled the one cylinder head so do I need to pull the other one to check it. It was running so well and the compression numbers good, I'd prefer to dismantle as little as possible.

Tim

[tim]

Greetings… So I took the head to Patrick Otis in Berkeley for evaluation. He soda blasted the head to get a better look. Today he called with the news. He could replace the one broken seat and it would run. I asked how confident he was in the other seats and he said he wasn't thrilled with their installation. The seats had been staked in place which he didn't think was the best way and some of the other machine work wasn't great. I told him "lets make it right" so all the seats will be replaced. This means removing the old seats, welding the head, re-machining for new seats, install seats and cutting them for the valves. Yippee. I'll pul the other head and get it to him next week. With that, I called off my trip to look at a drop dead gorgeous Jag XK120 coupe-disc wheels-spats that I have lusted after. Oh well' it's always something.

Tim

[cory]

Hi Tim,
I think that was a good decision. Why chance having happen what happened to my motor with broken valve seats floating around in the motor. It could have been much worse for you. Who did your heads originally? I don't mean to be nosey but I just wanted to store it in my memory for the future. Just as a side, the welding and machine work on my heads came to apx $6,000.00. With the rest of the materials and labor I am sure I was over 10k. Francois did the work. I would be curious to compare west coast/east coast pricing. You are definitely in good hands.
Cory