455 catastrophic failure
 

I had another thread about water sleeves missing on an engine. This is the engine. I was told it never overheated. i have my ideas on the cause but want to know what the actual smart people think. That's the 3 / 4 rod journal. Thanks

Not a great idea to jump to conclusions, but I will. From the pics, looks like oil starvation to 3/4, spun rod bearing, then everything else went to hell after that. Why the oil starvation? Low on oil, extreme cornering, or over revving the engine.

Maybe too tight of side clearance on those two rods started it?Like Mike said,oil starvation on them for sure.Tom

Would have thought it was 5/6 journal?

Is the cam broken in 3 sections?
Is crank in 3 sections?

The rods seized on that journal, broke a rod (or more) pieces went flying everywhere and took out the lifter bores and other stuff.

Surprised it ran long enough for all that though?
(usually puts a rod through pan and locks engine up)

:confused:

Crank stayed in one piece. Cam in at least 3 sections. Owner stated he was not running hard just driving to a car show.

ditto Post 2. Why is there a seed in sprout in a (2-bolt) Main boss?

That rod journal got hot!!!

Wondering how old the build is??? Miles???

Wondering, if it is at least a semi-fresh build, how it was built??? Just assembled, no measuring, no checking clearances. Possibly less attention paid to assembly, than even what I mentioned...

I've seen non experienced folks do stuff like this. They couldn't give you any details on what happened, because their engine building knowledge, was a zero.....

Very hard to believe someone was just "driving it to a car show" ... unless they had the radio up to 10 I'd think that bearing would have given some warning before it got so bad it grenaded. Looks to me like a "let's see how fast she'll go" explosion.

I bought one off a guy who was just driving to a car show. 455 was Not balanced by his buddy after a piston swap for more cr.
The crank Parted ways, rods junk, luckily block was saved.
This one didnt get like that from 1500 rpm cruising....

One set of .030 rod bearings on a .020 journal and others OK?

I'm thinking oil starvation from whatever reason would have shown up at least a little on other journals?

Looks like one of the factory cast Rods went out of round.

When this takes place the misplaced edge of the Bearing starts to scrape oil off the journal, then Bearing burns and the hammering that then takes place breaks or shatters the rod and at that point even at 2500 it's game over!

Back in 1998 I picked up a junk yard 2 bbl 455, all stock.

I pulled the pan off, checked all the bearings , installed a 60 psi pump, and even went so far as to yank out the two front galley plugs to run a 1/4" threaded rod in then to check how much crap had settled in there.

The motor in short was well taken care of from what I saw and the cylinder walls and the bottom of the piston skirts as seen from the crankcase side looked great.

I put in a 068 Cam and lifters that I got from HO racing that Came out of a 400 that I had put those in one year before .

I never buzzed the motor over 4800 rpm even for the few full throlle burst that it did with.

There are many other things like tuning that can be so far off even in just one cylinder so as to beat a rod out of round enough to cause the failure as seen in your buddy's motor.

Too bad, it looks like it had 4 bolt main caps also.

Two weeks later while just cruising out of my neighborhood at 1800 rpm a rod started to knock out of the blue.
I was able to turn around and limp the car back home at a rpm of just above 1100.

By the time I got into my drive way and back at idle the hammering was so dam loud it was like a guy with a jack hammer was inside the motor working away.

All the while the oil pressure was 40 psi.

Once a cast rod goes out of round due the bolts giving up preload or the Rods changing shape, then like I posted, its game over if the motor is above 2500 rpm , I just got very very lucky and was even able to save the Crank.

Naw, impossible. See, longk ago we bought a 70 AToll Blue GTO with a rebuilt 400 that didn't run right. Motor needed the rear oil Galley Plug. We drove it awhile with lifter tappings for about 300 miles, even up hills. Well, i pulled motr and found STD bearings on 010 cut rod journals. New rod bearings and that motor ran hard until we, gulph parted it out to reuse motor in the 1st OO Judge resto.

My thoughts also.

Rod 1 and 2 receive oil last.

The schematic starts with oil out of the filter on the left hand side.
R = rod.
M= main Bearing .
C= Cam journal.
IL= Intake lifter EL = Exh lifter

Except that would increase clearance where my suggested .030 bearing on a .020 journal would tighten that bearing snug around crank journal.

To do that much damage at "cruising speed" and not hear it the driver was deaf as a stump or he liked his subwoofer more than his engine. That had to have made noise for a while.

With that much carnage, root cause may never be known...

But yes, hard to imagine rod bearings being that bad without it signaling before final fail.

I once bought an engine that had been "rebuilt" but was locked up. The PO had assembled one rod cap with a bearing shell rotated out of position by at least 15 degrees. That engine did NOT turn.

I think it started making a noise and he figured he would drive to his
destination rather than walk. Been there before LOL

GT

It looks to me that detonation could have been happening from the looks of the lower main bearing sitting on the block. Wear in the center of the bearing. Did detonation pound out the bearings? I'd be interested to see what all the rod bearings look like too, along with the lower half of all the mains.

After turning 400s, and 428s with stock rod bolts in stock rods over 6000 RPM myself for 2 seasons of racing on dirt tracks. I've also run stock rods, and rod bolts over 7000 RPM on a street 400 engine, with heavy stock cast pistons. I'm not buying the rods went out of round. They're tougher than people give them credit for, they're not made out of porcelain, glass, or china. Also the rod bolts will run with no bearing left, and hammer quite hard before they actually break in half. After doing a lot of autopsies on Stratostreak V8s, I can usually see a chain of events from taking all the components apart.

More likely the rod bearings didn't have enough clearance for any abuse, the crank gets hot, causing less oil clearance, and it grabs a bearing. Now that crank didn't get that black in an instant, it was making noise before the rods broke. Sometime the rod bearings spin but after the tangs gets flattened out it spins both bearing halves inside of the rod, without any oil on the back side of the bearing it gets hot fast, then the destruction happens. I have seen that scenario too.

I'd like to see what all the rod and mains look like, before assigning a cause of the destruction. There could well be other bearings that were on the verge of spinning, but without seeing them, we're shooting in the dark as far as causes.

Also talking about just cruising to a show, what rear axle ratio was in the car? It could be from a 2.56 axle, to a 4.33. It makes a ton of difference what the axle ratio was, as to what RPM this happened at. What torque convertor was in it if it, was an automatic car with a high stall convertor? From my own experience, when things go sideways at 3000 RPM, it can cause the same destruction as shown here, speaking from experience.

I've lost 2 engines in the past at cruise speed that the bearings weren't the cause. One a valve head broke off causing a whole chain of events. The other, a thin wall 389, bored .060 over cylinder wall collapsed, stuffing the piston into the water jacket, total destruction to block, and crank. Rods bent a lot before they broke, and some never broke, they just bent. That is the reason I don't buy that rods distort, and snap, I've seen the contrary evidence that they take a lot of abuse, before they fail catastrophically.

Take a Pontiac with a stock bottom end, with .001-.0015 bearing clearance. The crank gets hot from beating on it, the oil clearance goes to next to nothing. With no heat being taken out by oil flow, the crank grows further, until the rod bearing adheres to the crank, and spins. Meltdown has begun, like a runaway reactor in a nuclear plant. Had the rod bearing oil clearance been .002-.0025 beforehand, the engine would run fine, for a long time. Pontiac factory Ram Air engines bearings were .001 undersize from day one. Same with main bearing clearances, they're too tight as they come from the factory. On the performance engines, many came with full grooved mains, while the everyday engines only had the upper half grooved.

Oil supply, and oil clearance makes a huge difference in longevity in Stratostreak V8s, because the cranks are so massive, and with large journal sizes, they tend to generate more heat, and grow more than other makes of engines.

Case in point was Smokey Yunick wanted the Pontiac engineers to keep the 3 inch main size in the 421 engine for friction reduction, he was right, for performance applications, it does work better.

:2cents:

Being a 455 block, inspect the bulkheads from the cam tunnel to the main bore. Possibly cracked in one bulkhead and lost oil pressure.
(still would make noise with that black journal)


:confused: