small block chevy spun rod bearing

In this video I show what a spun bearing looks like. I also talk about my 305 chevy rebuild project. My plans is to build a stock 305 chevy engine and turbo charge it. This spun bearing was out of an engine that I was taking apart so that I could use the rotating assembly on a 305 factory roller block that I am building.

[@Mr39036ce]

common stuff D. Seen many a dead one back in the day. Prob ain't the mill it's everybody that has one thinking it's a Z 28 302 motor.

[@realdeathpony]

I have a 91 305 that I put rebuilt 081 tpi heads and a ramjet cam. Thing ran great in my wagon. Sitting on a stand because I did a LS2.

[@davidcraft4909]

I will eventually get into LS engines, but I wanted to mess with the old school small blocks for a few more years and do something I have never done before. I want to turbo charge a 305 and then a 350. Thanks for watching and commenting.

[@hughobrien4139]

I’ll lend two bits of advice- information.
First. Anytime a rod bearing or main bearing fails, there is friction-heat generated that is obvious.
What is not obvious is the magnetism that generated because of all of the friction and heat. You can grind that crank and recondition that rod, but if those parts are not demagnetized every metal particle in that engine will be attracted to those parts and their surfaces.
A very real detail that is often ignored.
The next it is that the 305 and 350 Chevrolet have the same stroke and basically the same crankshaft.
Often these two crankshafts are swapped out for one another in exchange situations for more quick fixes and even in a major overhaul.
Here again the detail is quite obvious in that the two crankshafts have two different balances because of the weight of the piston.
What happens when these are swapped is generally never noticed and I’ve seen this seemingly work perfectly.
In reality you must know that there is a gross imbalance in the reciprocating mass that is generating harmonics that you likely can not hear.
Harmonics will ring at levels not audible to human ears but that ringing is certainly impacting bearing surfaces all throughout the crankshaft and the bearings do exactly what you’re seeing here. They’re falling out of their housing bores because they’re taking a beating.
You’ll also likely get the idea that some of those bolts may have not been torqued down. Another phenomenon that occurs during gross harmonics is that threaded applications get slowly rattled lose making it seem like they were never torqued in the first place.
This should make it clear how a bearing failure manifests. It should also lend a clear understanding that the money saved by not dynamically balancing your engine can be a bigger gamble that once thought.
One last note. That rear cap appears to be blackened. I would make sure you do not have a burned rear main bearing or burned thrust surface on that rear bearing.
This can indicated a ballooned converter or bad clutch setup. Maybe a pilot bushing installed where it should be.
These are just a few high point details. The rabbit hole gets deeper but I’ll cut it short to this.
Hope this helps.

[@davidcraft4909]

Thanks for the info. I will be trying to keep a factory matched rotating assembly, and if I do have to replace that rod, I will make sure it weighs the same as the rest of them. Also, I will be comparing the weight of the new pistons vs the old ones. If I change anything more than a few grams, I will get it balanced. I am aware of the thrust on a crank. I will be taking my crank to a machine shop and have them check it out and turn it. The magnetic stuff you mentioned is new to me, and I will read up on that. Thanks for the advice, and thanks for watching.