Hot Rods A catastrophic failure

Ouch! This is what happened to my ARDUN flathead Wed. I would like some input. I don't know who built the engine. It was built about 8-9 years ago. I bought it early this year.
Apparently it sat most of the time. I drove it maybe 50 easy miles then blewey. All fluids were changed and everything checked as you would for a car from sitting. Looks like it was built right. Ross pistons, h-beam rods, Heavy duty main caps, Looks like a billet crank, ARP bolts etc.. Looks totally fresh. The cam is broken in half. One rod cap went through the side of the pan and those rod bolts are separated in the bottom of the pan. Wondering if those came loose. The block is broken too. The other rod is broken in half but it's still on the crank. Maybe the cam Broke that's the cam in the pan ? I know There will be questions but this is all I can think of now. Thanks, Jim

 

Title definitely sums it up!!! I'm betting rod bolts not properly torqued or something on those lines..... How are the heads? Hopefully you can re-use them. I'm sure you have a bunch in this.

 

Holy shit! How many R's was that thing turning when it came apart? Nuts. Any damage to the heads? If there's any bright side, a bottom end is probably cheaper than another set of Ardun heads.

 

Rod bolts coming loose usually make some noise before total failure, but the cap and bolts laying in the pan make a strong suggestion as to what happened. Are the others all as tight as they should be?

 

Does the broken rod that is still attached to the crank have a spun bearing? If there is a spun bearing on that rod, I lay the blame on the spun bearing. The bearing spins, the rod temporarily welds itself to the crank, and breaks the rod, and the broken rod attached to the crank make a mess. Sometimes the wrecking process frees the welded rod and it flops around loose, and sometimes it remains welded.

If the rod cap nuts came loose and the cap came off, the parts bouncing around inside the block and pan will tear up everything. Still betting on the spun rod bearing though. Gene

 

Too much nitro. Told you to not put 100% in it.....

 

Did a wrist pin seize due to lack of oil? Bob

 

My condolences...

 

Truly sorry to see this.Reminds me of why I build my own engines.

 

Quite a cast-iron convulsion.

 

Man,I hate to see that,I know Arduns don't come cheap,I hope the heads weren't damaged. HRP

 

What's the main webs look like? How much HP can a 3 main V8 stand.

 

You appear to be taking it in a much calmer fashion than I would!

 

I've seen this before when a CAM bearing seizes along with a main. It breaks the webbing in the block and kick all the parts to the pan.


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I guess an examination of the cam and bearings will be in order but unfortunately won't bring this engine back.

 

You mentioned H-beam rods which the originals were and I believe cast steel. Are these are either an aftermarket rod or from another engine? V8-60 rods had studs and nuts, these appear to use the ARP rod bolts, no nuts.

Having experienced the same thing on turn two at Centuria,with a flat head, I know how quickly you come to a halt, and how many fragments and how much shrapnel is left in the pan and on the track.

Now here's a little known fact...Rod bolts and their mating rod nuts have specific diferent Brinnel hardness design values that make them compatible. I have first hand knowledge from Federal Mogul back in the 60's on an Industrial engine we were using that was throwing rods sporadically.
We ran 100 rod nuts from our service parts stock through incoming inspection and found almost half were too soft according to the manufacturers blueprint. The manufacturer acknowledged the problem by extending warranty.

In your case, might focusing on using the high strength bolts have created a situation with the material of whatever the presumed threaded holes in the rods were! All speculation.

 

those rod bolts came unscrewed, eh? (and the rods don't use nuts, eh?)

 

Thanks for sharing the bad news...that hurts for sure. Very rare stuff. I hope it can still be salvaged.

 

Be sure to post if you find out who built it and why it failed.

Charlie Stephens

 

would be interesting to put a beam torque wrench on a few of the other rod bolts, see what they are torqued to...and figure out what they are supposed to be torqued to. Look like SCAT rods, eh?

 

I am sure it was under 2500 RPM. I will check the other things mentioned and post. Ran out of time today. One thing else. It has a 5000cc SCOT blower at 6lbs. . Thanks for all your replies. Jim

 

looks like the threads in the rods pulled out . seen this happen with too good to be true rods , and some counterfeits , material too soft or threads not correctly made .

 

Damn shame,good luck figuring out what the cause was.

 

I.m betting on your right shoe weighs too much...com'on admit it

 

Ouch!
Clean up the broken parts and lay them out on a table in the order they were assembled---- kind of like an aircraft crash reconstruction. That may provide clues as to what broke first.

 

I use Scat rods, never an issue and they come with ARP hardware. Like Jim suggests, check the torque on a few other rods and even the mains. Clean up everything, try to match up what came from where and take a good look at it.

 

As a vehicle mechanical failure investigator I have seen this damage and at first it would seem hard to determine what failed first. Like stated above^ clean all of the parts and lay them out. Check the torque on the other rod bolts. There will be thread material on the rod bolt if it pulled out. If it came loose you most likely will find a bent rod bolt on the other side. Broken small end on the rod might indicate a seized wrist pin, broken piston or dropped valve. Rick

 

Wow, my condolences for sure, hope at least the Ardun heads are ok! What a heartbreaker. This is why I'm leary of running someone else's fresh rebuild. The only way to confirm something was machined/assembled correctly is to completely disassemble and reassemble doing your own cleaning, inspection, mic, torque wrench, etc work before running it.

Did you drop the pan and confirm torque on the rods, mains, etc. before running?
Any noise or oil pressure issues in your 50 miles?
Curious to know if the cam is decades old stock or a new cam (?), though I agree it's likely spun bearing or con rod bolt related failure.

 

In the middle of your debris field is an item I don't recognize. Kind of shaped like an ignition coil. What is it?

 

Time for failure analysis . Sorry about your engine.