cudak888: 1972 Q-code - cam failure pictures

[cudak888]

Photos, as promised:

Passenger's side cylinder head:

Notice the difference in the soot texture between #1 and #2:

Pistons in block:

#1 at TDC - note those strange nicks in the center and the grime:

#2, #3, and #4:

-Kurt

 

[matrixx]

Hmm Mrs valve wasn't faithful so seems Mr Piston knocked her up.

Sent from my SCH-S960L using Tapatalk

 

[mjlan]

Those don't look alarmingly bad. Quick check would be to flip the head over so the chambers are up and fill each chamber with lacquer thinner (or your solvent of choice) and see if it leaks past the valves. This will tell you if you have any bent ones.

As far as the carbon and strange marks, I would suspect worn valve guides on Cyl. 1 letting some extra oil in there. What do the valve stem seals look like? If the valve springs have been changed, the seals should have been replaced as well. Who knows where the marks came from, something could have fallen into the cylinder... At any rate they won't hurt anything.

 

[cudak888]

Hmm Mrs valve wasn't faithful so seems Mr Piston knocked her up.

The contact marks on cylinder #1 are not from a valve. It is physically impossible for the valves to touch the cylinder at that point unless alarmingly bent.

Those don't look alarmingly bad. Quick check would be to flip the head over so the chambers are up and fill each chamber with lacquer thinner (or your solvent of choice) and see if it leaks past the valves. This will tell you if you have any bent ones.

As far as the carbon and strange marks, I would suspect worn valve guides on Cyl. 1 letting some extra oil in there. What do the valve stem seals look like? If the valve springs have been changed, the seals should have been replaced as well. Who knows where the marks came from, something could have fallen into the cylinder... At any rate they won't hurt anything.

The valves are original, but my guess is that the stem seals or guides may have been replaced; thereby contributing to the bent pushrod issue.

Haven't done anything to the heads past what you see there. Yet.

-Kurt

 

[cudak888]

Did the acetone test. Not a single solitary leak.

I'm convinced that the pushrod damage in this engine is due to improper cam break-in OR overly-stiff double-springs, OR a combination of both.

Started to pull the LH head today, but got slowed down by the LH header collector. Got it off, but the head will have to wait until the weekend. The very last bolt holding the header on the RH side snapped off in the head. Oh, joy.

-Kurt

 

[matrixx]

Maybe something fell inside like a small nut or something.

Sent from my SCH-S960L using Tapatalk

 

[cudak888]

Maybe something fell inside like a small nut or something.

The P/O's manhood?

-Kurt

 

[Luke]

Kurt the Marks on the piston almost look as if someone has pushed on the piston with a screwdriver. Anyways looks like you may have avoid total disaster.

 

[cudak888]

FYI, a friend of mine has a Bridgeport mill. Should be able to block the head in place and gradually drill the stuck bolt out with left-hand carbide bits.

Kurt the Marks on the piston almost look as if someone has pushed on the piston with a screwdriver. Anyways looks like you may have avoid total disaster.

Good guess. At any rate, it doesn't look serious at the piston tops. I'll be really lucky if they didn't do anything to the bottom end at all.

-Kurt

 

[cudak888]

Got the left head off today. Unlike the right, there is some weird stuff going on here.

See it? Cylinder #6 has a pit in the top of the piston - right where the stamped arrow marking is located. It's not from a valve, and there's no other damage on it. Detonation?

Out comes the head - and header. Figured that it'd be less work to yank the whole thing out as one and deal with the rusted-up header bolts out of the car.

Much to my surprise, the header bolts on this side gave no trouble. Go figure.

BUT...

The intake valves on #5 and #6 do not seal to the point where you can see light through the gap. The shown photo is of #6, which is much worse than #5 (which wouldn't photograph as easily), even though the photo of the acetone test suggests that #5 has a bigger gap than #6:

Just to refresh everyone's memory, the one left-hand pushrod that bent was on cylinder #7, not #5 or #6. That, and the valves show no marks of having hit the cylinders (nor is that weird mark on the top of cylinder #6 shaped or lined up in such a way for the valve to have made the mark):

If anything, this head has to go to the machine shop - but I'm more concerned with what has caused the valves not to seat correctly at all - and why? Not to mention that pit.

-Kurt

 

[caspianwendell]

Had a chevy do that same thing, it ended up being the guides frozen to the valve stems. check to see if the valves slide easily.

 

[cudak888]

Had a chevy do that same thing, it ended up being the guides frozen to the valve stems. check to see if the valves slide easily.

I pulled the valve spring compressor out today to do just that - and then laughed at myself, because I realized it'll only compress the outer spring.

I found a C-clamp style compressor in the shed (30 years of Dad's diesel repair stuff - more tools than I know what they're for), but it is a worthless junker from Sears which is probably good for nothing but a lawnmower. It doesn't even have a proper release lever. Pulling the locking key backwards under tension is akin to playing with a land mine. I don't usually advocate getting rid of ANY tools, but stay away from this POS if you ever see one:

That said, I took a break from the engine today. With the help of BigBlue, I have solved the one thing that has been bothering me since the car was delivered: You can't roll it around on flat tires.

The Magnum 500's on BigBlue's parts car had good tires, but they also had wheel locks with an obsolete pattern - and no removal tool. A few hours of grinding, hammering, and twisting later yielded three of the four wheel locks, which was enough to get junker Eleanor looking decent:

At least it isn't in a state that allows everybody to laugh at it (not to mention laugh at me once they've got their kicks laughing at the car).

She rolls free and easy now; I can free myself of that concern.

With that, I'm putting Eleanor on hold until I can get a proper spring compressor. That gives me time this week to permanently weld the quarter on neglected Soylent Green, who's been moved into position for the weekend welding:

"Soylent Green, meet Soylent Yellow..."

-Kurt

 

[caspianwendell]

You can take a block of wood, and a hammer to them, if they don't bounce you know it's the guide

 

[cudak888]

You can take a block of wood, and a hammer to them, if they don't bounce you know it's the guide

Right now, I wouldn't trust any test in that manner. The double springs are way too stiff - I'd expect the block of wood to take on the impression of the valve top and retainer before seeing the valve move.

Incidentally, I suspect that the double springs may have been the source of the pushrod problem. I'll bet anything that the inner springs were used during the P/O's "break-in" (where he damn well broke it in, all right).

-Kurt

 

[cudak888]

Oh, and did I mention that someone "upgraded" the rear brake lines with their own homespun work?

I didn't get a photo of it, but I'd be wrong to say it looks like a child did it. Given what the bending looks like, saying such would be an insult to the kids.

-Kurt

 

[cudak888]

Got a valve spring compressor on its way.

FYI, I'm informed that the springs that were installed in it are single springs with dampers. If they put the Comp recommended 940-16's in it, the specs as follows:

Seat load: 93 @ 1.900

Open load: 237 @ 1.300

Coil bind: 1.200

Rate: 241 lbs/in

By comparison - this PDF gives stock spring specs for the 351C 4V as follows:

Pressure:

85-95 @ 1.820

271-199 @ 1.320

Wear limit:

79 @ 1.820

244 @ 1.320

Free length (approx):

2.05

Spring assembled height, pad to retainer:

1-13/16" to 1-27/32"

No other useful info.

At any rate, the dampers shouldn't have been in there for break-in. I'm not going performance-nuts on this build, and I don't want to take the heads off to put dampers back in. Single springs at stock specs it shall be.

-Kurt

 

[Totalled]

The dampers really don't increase the rate much. Those are the same springs used on my comp hydraulic roller. They aren't that stiff. They probably didn't A: use break in oil with zinc. B: didn't keep the RPM up or varied it.

 

[cudak888]

The dampers really don't increase the rate much. Those are the same springs used on my comp hydraulic roller. They aren't that stiff. They probably didn't A: use break in oil with zinc. B: didn't keep the RPM up or varied it.

Ok, let's go with the theory that the double springs aren't the cause of the bent pushrods.

If so, the next thing down the line would be the mushroomed lifters binding in the block - but if that were the case, wouldn't we have seen at least four valves smacked at cylinders #2, #3 and #7? At worst, we have two valves bent at cylinders #5 and 6, and zero indication of them having smacked the pistons.

It just doesn't make sense, and that's what bothers me. I am not going to start throwing parts at it until I know what caused the stock pushrods to fail - because they didn't fail on their own.

Furthermore, the break-in procedure is pretty much a case of the darn engine starting up right the first time - and to continue to do so for 30 minutes. No workie, cam wipey.

Funny thing, I learned this evening that at least one of the cams that came with the 400 (dare say not the '77+?) cam isn't that far from the 351C 4V:

351C 4V:

Lobe lift: Int 0.247 / Exh 0.262 /// Theoretical lift: Int. 0.427 / Exh 0.453

400 2V:

Lobe lift: Int 0.247 / Exh 0.250 /// Theoretical lift: Int. 0.427 / Exh 0.433

This will sound stupid, but I know I can dig up more than one 400 with matching lifters at the junkyard. Question is - truck cam or not? Who knows? Too many variables to be feasible.

Nah.

-Kurt

P.S.: On that note, it remains to be seen whether the lifters scored the block to the point of sleeving.

 

[cudak888]

Let's consider this mathematically. Rough measurements, for now - really didn't figure on calculating this now:

The worst pushrod measures about 207mm after being bent out of shape. The proper rod, by comparison, is approximately 213.7mm (8.412" to be exact).

That's 5mm of metal pressing against each other to account for.

That said, there's an interesting comment relating to 400/351M's in regards to this. Seeing that the heads are based on the 2V, this may not apply, but it's interesting to note:

Stock intake valve springs go solid (coil bind) at 0.490" valve lift. The stock springs on early non-rotating exhaust valves allow the same lift as the stock intake valve springs, but the springs on the later rotating exhaust valves go solid at just 0.480" valve lift.

Not that we're dealing with stock springs, but that Comp 268H / 32-221-3 has 0.494" of lift.

Going to leave this here for now and come back to it in the morning when I can verify what data goes to what and where - and then see if anything of it makes sense.

-Kurt

 

[Gold Rush]

Something looks funky with the bent pushrod. I wonder how long it is straightened? Could they be 400 m pushrods?