Broke connecting rod?

[Old School]

The piston dings come from bouncing around in the cylinder after the rod broke and hitting the edges of the chamber. Bearing looks good, everything but the rod looks good, it just broke.

May have been mentioned before, any chance the engine is loading up on fuel and hydraulicing? Maybe put a gas carb on in and see if the carnage stops?

[lance flake]

The piston dings come from bouncing around in the cylinder after the rod broke and hitting the edges of the chamber. Bearing looks good, everything but the rod looks good, it just broke.

May have been mentioned before, any chance the engine is loading up on fuel and hydraulicing? Maybe put a gas carb on in and see if the carnage stops?

I was wanting him to do away with alcohol injection this time. I like a gasoline carb set up myself.

If it hydrauliced i would have though the rod would have bent first and burnt the bearing and/or wrist pin up causing failure. I suposse the rod could have just shattered if this was the cause.

I really hope it wasn't just parts failure. That would really be terrible.

[Rick360]

Maybe his tach is wrong and he is constantly revving it higher than it appears.

Rick

[Roundybout]

It looks like something got in there with those divots/cuts. There's no missing pieces that would cause that carnage, or really lack of carnage. Everything looks good other than the broken rod. If it just failed I don't think we'd see those witness marks, especially the chamber picture. It's odd though not much evidence of anything passing the seat/valve. Did this happen at low RPM? I hate that saying bad things happen in threes but I think this may be the case here.

[lance flake]

Maybe his tach is wrong and he is constantly revving it higher than it appears.

Rick

I don't think tach is wrong. He has a electric shifter with rpm chip at 7200 and a high side rev limit of 7800 so both would have to be bad for an over rev condition

[lance flake]

It looks like something got in there with those divots/cuts. There's no missing pieces that would cause that carnage, or really lack of carnage. Everything looks good other than the broken rod. If it just failed I don't think we'd see those witness marks, especially the chamber picture. It's odd though not much evidence of anything passing the seat/valve. Did this happen at low RPM? I hate that saying bad things happen in threes but I think this may be the case here.

The marks in the piston and head were something passed through it are very small. You could polish them out and never know they were there. I just can't make myself believe this small of an object could break a rod. Like i said i have seen complete valve heads broken off and rod not broke

[prairiehotrodder]

i hydraulic locked a motor when gasoline from a nitrous fuel solenoid stuck and filled one cylinder with gas. It bent the crank and ripped out the 3 center main bearings but did not hurt the piston or the rod. The nitrous bottle was not even turned on. Just gas. Not sure what happened to you. Is there a way to turn on the fuel system on the floor and see if the injectors are all working properly ?

[lance flake]

i hydraulic locked a motor when gasoline from a nitrous fuel solenoid stuck and filled one cylinder with gas. It bent the crank and ripped out the 3 center main bearings but did not hurt the piston or the rod. The nitrous bottle was not even turned on. Just gas. Not sure what happened to you. Is there a way to turn on the fuel system on the floor and see if the injectors are all working properly ?

It is mechanical injection. Belt driven fuel pump.

I had a customer with a efi turbo deal several years ago that had a rod break upon disassembly we found 3 other bent rods. He put it all back together and found his injectors were shorted to power and flowing with the key on. They were 160 lb injectors so it filled it quick. I know that one was hydrauliced

[Tom Walker]

Please keep us posted on what you find out is the cause of the failure please. Would be very interested in knowing what is the primary cause of this carnage. Good luck, and I feel for this poor guy, what a run of bad luck.

[cgarb]

mechanical injection...does he have a primer solenoid on the car by chance? I know Ron's set ups use a nitrous solenoid to prime them with gas to get the motor started. Maybe that could be stuck or leaking or perhaps over used by accident and hydraulic locked a cylinder. Just a thought.

[stealth]

Could this mark in head be contact with piston? Look like distorted material at head. Piston would wedge and cause rod to buckle as shown

[lance flake]

Could this mark in head be contact with piston? Look like distorted material at head. Piston would wedge and cause rod to buckle as shown

That mark was left after Rod broke Pistons was twisted slightly. I think the bottom broke part of the Rod slapped the piston back into the head after it broke

No primer pump on set up

[needforspeed66gt]

Is that a Callies Ultra rod?

[Newold1]

Still a bit of a semi-intelligent guess, but there could be some other fueling and loading questions.

Rod failures like this usually come in one of two states, under Compression or under Tension.

Extreme compression of the rod from let's say pre-ignition or detonation will normally start showing up in bearing pounding of the upper shell and when it gets bad enough for long enough you can have rod bending and outright failure. Improper timing and advance issues would show up here and can cause rod compression failure.

Extreme tension (pull) of the rod from let say extreme high rpms, rods not strong enough for the application or rods with cracks or failure points in the rod will pull apart and send the piston up into the opening valves, beat the hell out of the block and cylinder walls and such and bend valve and damage the chambers from the damaged valves and piston domes twisted off axis in the bores. This type of failure usually is quick and without any form of pre-warning.

Based on the pics and information supplied here my GUESS is a tension failure and because it appears so quickly there is no obvious lower bearing shell wear or crankshaft damage apparent.

I think it might just be a case of structural rod beam failure. X-ray and measure those remaining rods and it might be time for a new stronger set. JMHO

[P R S]

Check the butterflies for missing hardware,I had a customer lose 2 of the 3 Allen head bolts from a Ron’s toilet on a new build with 3 runs.got lucky and only dinged up a couple pistons but it took awhile to figure out where those bolts came from...