It's probably cylinder # 5 where the exhaust valve seat dropped out of and got pounded to bits.
Pieces of steel in cylinder??
- Thread starter Righty Tighty
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It's probably cylinder # 5 where the exhaust valve seat dropped out of and got pounded to bits.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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hokie-doodle that seat is wide! Or am I not seeing the right surface?
Cuda416
Well-Known Member
nm9stheham
Well-Known Member
You're seeing it right.... maybe a too-small seat got put in. There are a ton of different seats sizes out there and wo knows what migth have been used because it was on-hand.
As said, the OP needs to pull out #5 exhaust now and see if the seat is gone. That is the one that is badly sunk.
Yes, you can see the gap around the #5 sunken exhaust valve where the hardened seat is missing. It will stick out like a sore thumb when he pulls that valve out.
Well gents (and ladies?), here you go. Lost a valve seat in the #3 exhaust. I’m so relieved to finally solve this! I’m also relieved to know that it wasn’t someone messing with my ride.
New guides, too. I would be suspect of everything. But these old 675 (If they are original to the car) heads have some power potential on an eighteen.
Damned if I wouldn't take that back to the shop that did it. If for no other reason to show them what crap work they do.
There's no evidence they even staked the seat. Nowhere.
nm9stheham
Well-Known Member
Always good to find the real cause!
IMHO, I would think twice before re-using those head. Yes, they have been gone through, but obviously not in a quality fashion. No telling if all the insert work is marginal or not; look at the big step under the seat in #7. And there is a lot of erosion/rust pitting in the throat under the #3 exhaust seat. Not suggesting you make big upgrades just for the sake of more HP and torque (and since the rear axle may not take it).... just for getting good, reliable parts in the engine.
Cuda416
Well-Known Member
Probably the most important thing right there. If someone had done it once, they could do it again after money was spent.... Glad this was solved ...
"If you don't point out when people are being ignorant and stupid, they will keep going around thinking it's ok..."
Gallagher...
I was thinking the same thing. If they did it once, what’s stopping them from doing it again?
So, playing devil’s advocate here. What if the last shop who had hands on it did everything right, and the seat failed from me driving it so hot? The driver side valve seals were all pretty burnt up, and I know for a fact the headers on that side had a leak after I installed them.
So, playing devil’s advocate here. What if the last shop who had hands on it did everything right, and the seat failed from me driving it so hot? The driver side valve seals were all pretty burnt up, and I know for a fact the headers on that side had a leak after I installed them.
GEO
Sarcasm Inc.
Well now you know , I'd throw the whole pile away and get a 360 to build.
Well, some exhaust valves you've pictured sit proud (correctly) in the head and some low (incorrectly). So that right there means they did a crappy job. Also, as I said before, there are ZERO signs of stakes around any of those exhaust seats. That's an important step to help keep the seats from falling out. So in short, they screwed up. One more point. 10,000 plus HP top fuel engines ALL have hardened seats pressed into aluminum heads. Do you not think they drive those hard?
The hardened seats are interference fit... The machinist must get the interference correct or they will not be held in tight enough...
My head guy uses dry ice to cool/shrink the seats before pressing them in.... This helps get the interference fit needed to retain them while reducing the force needed to press them in properly...
Running the engine too hot can loosen the interference fit for the seats and can reduce the interference fit and retention of the seats...
nm9stheham
Well-Known Member
While it is possible, it is not at all probable that overheating was the cause. It's far, far more probable that this failed due to poor workmanship.
BTW, you actually got quite lucky with this failure. The usual outcome is that the seat drops, jams the valve open, the piston hits the valve repeatedly and eventually breaks the valve head off, which tumbles around, eventually jamming sideways between piston and cylinder head. At that point, the head busts, the piston busts, the rod bends, the cylinder wall cracks, or some combination of those things.
So IMHO, it's risking terminal engine failure to use these again. And I'm pretty dubious that these can be re-worked with new seats that will hold in unless you go to larger seats and valves (which certainly is possible). But with all that, it is a good time to re-think the head selection options, at the very least. Your budget and how you want to use this engine/car ought to be stated.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Hmmm, very tempting. I suppose eating macaroni and cheese for the next year won't be all that bad...
I was thinking the same thing. I have a feeling the seat failed just before I parked it last to repair the coolant leaks. So, the running theme here seems to point me towards either new heads or a new engine. I was just gonna take my current ones and have a shop replace all the seats, but I don't think y'all would agree.
My intent with the car is to have it as a daily driver with some added HP for a little get-up-and-go when I wanna get-up-and-go. I won't be taking it to the track or anything, just a grocery getter that goes fast. Initially, my plan was to add headers (done), upgrade the intake, carb, and air cleaner, and pretty much call it good. But that was just a beginner's plan...
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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All the more reason for a 5.9Magnum
The major increase in low-end torque will be worth every box of MacNcheese you have to choke down. And the bonus is that, with the 5.9, you won't have to be using as much throttle to get the job done, as the teener would have needed. The potential for a reduction in fuel useage that, that the higher compression 5.9 has, over a cammed up 318 (however small the cam), will pay dividends in the long haul.
And finally; the go fast parts (headers, carb and intake) will have the potential for larger increases on the larger engine.
A 360 is "only" 42 cubes bigger than a 318; but those 42 cubes at stall speed are worth more than any bigger cam that you could ever install into your stock-compression-318,ever. Those 42 cubes at stall-rpm, are probably worth more than the headers, carb and intake all put together, installed on your 318. In terms of performance; 42 cubes is like adding 13% to the rear gears behind your 318; like going from 3.23s to 3.55s, while simultaneously going up in stall some 300 or more rpm..................... without actually doing it. And this is just ar stall-rpm.
By the time you get your heads gone thru, and cylinders rebored/repopulated, and whatever else you're gonna find wrong in that pile, a used drop-in 5.9M is likely gonna be cheaper, or at the very least, within reach. And this is a zero-dissappointments swap.
nm9stheham
Well-Known Member
Actually, that is a pretty good plan for a grocery getter IMHO.
Honestly, maybe you should check in the local boneyards for a good used 5.9 Magnum. I have no idea what they cost out there.... in my neck of the woods, they are pretty reasonable. There is a subforum here on FABO about Magnum swaps that might be worth checking out. It's not original, but it will be quite step up...more cubes, better compression for low RPM torque, better breathing parts overall, roller cam, so no ZDDP issues. May need a different flexplate IIRC, and I am sure there are other bits to change, but it sure would be an easy upgrade. (And of course, you could get a poor/bad one too.) Edit to add: I see that AJ and I were typing at the same time.... great minds and all that rot LOL
Honestly, maybe you should check in the local boneyards for a good used 5.9 Magnum. I have no idea what they cost out there.... in my neck of the woods, they are pretty reasonable. There is a subforum here on FABO about Magnum swaps that might be worth checking out. It's not original, but it will be quite step up...more cubes, better compression for low RPM torque, better breathing parts overall, roller cam, so no ZDDP issues. May need a different flexplate IIRC, and I am sure there are other bits to change, but it sure would be an easy upgrade. (And of course, you could get a poor/bad one too.) Edit to add: I see that AJ and I were typing at the same time.... great minds and all that rot LOL
Thanks guys, I'll start looking into the 5.9. Pardon my ignorance, what do you mean by ZDDP issues?
yellow rose
Overnight Sensation
There are really only two things that make a seat fall out. Heat and bad machining.
Heat because of slow timing (another reason to get the timing correct). The easiest, most simple way to remove a seat is to heat it up. Once it cools, they fall out.
The other is machining. If the fixture and tooling aren't absolutely rigid, the bore will be out of round. And no matter what you do, the seat will fall out.
No chemicals, no mechanical methods will keep a seat in if either (or both) of those things happen.
Heat because of slow timing (another reason to get the timing correct). The easiest, most simple way to remove a seat is to heat it up. Once it cools, they fall out.
The other is machining. If the fixture and tooling aren't absolutely rigid, the bore will be out of round. And no matter what you do, the seat will fall out.
No chemicals, no mechanical methods will keep a seat in if either (or both) of those things happen.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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ZDDP is an additive that Dyno oil used to have in it ( see edits below) that was a sacrificial ingredient between the lifters and the cam nose. It's job was to prevent metal to metal contact between these highly stressed working surfaces.
When the oil companies started not putting (Edit see below) it in any more, a lotta guys, me included,with FTH (Flat Tappet Cams) suffered catastrophic camshaft failures.
Magnum engines have roller lifters with little tiny wheels on them that roll along the cam lobes and so drastically reduce the pressure on them and the wheels.
This is a bonus to you, cuz you don't have to add the ZDDP at every oilchange anymore, which you should have been doing to your 318LA engine......... Well, those grocery-getter engines with hiway gears, will probably survive with low-ZDDP oils due to their relatively low over-the-nose spring-pressure and lower operating rpms.
I mean 4500rpm with 2.76s is ~50 mpg in first gear, and who does that....... all the time?, lol.
Corrections;
used to have lots of; and
Started putting not as much in
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yellow rose
Overnight Sensation
All engine oils must have zinc in them or they ain't engine oils. They have reduced the zinc because of catalytic converters. More junk government regulations causing more junk regulations.
Too much zinc is a power killer. So it goes both ways.
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