BBC Spun a bearing

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It should be out and apart tomorrow.

Thanks for the experienced thoughts.

Gary

 

Hi, my engine was full of shavings also after losing 2 lobes on cam. Then the bearings where scored by shavings in oil, so still might pay to have a look at the cam when you take it apart.

 

Thanks I pulled the engine today. Will put it on the stand Monday and take it apart. Don't know if the cam was run in when first started. This time after rebuild I will make sure everything is done right.

 

Just pulled the pan and valve covers. The # 1 & 2 rod bearings are spun and a couple of rocker arms are flopping around. Not sure what went first the rods or the cam but there is a lot of junk in the pan and oil pump screen. Looking for a good rebuilder in Nor. Cal.

 

Why not go back to the guy you bought it from, he assembled with a problem, let him step up to the plate! Good Luck!

 

Some of the Causes
Over revved.
low oil, or oil pressure
not enough bearing crush probably your problem
not enough bearing clearance

 

losing #1 and #2 rods kinda makes it look like an oil starvation issue. They're furthest from the pump.

 

Kinda stepping back and hoping he will step up.

Good thought.

 

Screw me once, shame on me. Screw me twice, it ain't gunna happen. I wouldn't go back.

 

Whatever that means? Thanks for the thought.

 

I have built at least a hundred BBC's and always set the crank on the loose side. I always recommend 20/50 oil. I don't have any coming back with bearing issues. I do always recommend pulling the oil pressure gauge off the front of the block at the first side port, Chevy did make this change and it was a good one, this gives you the oil pressure at the last main receiving oil not at the rear before anything get its oil. I still have racers who check pressure at the rear and don't understand the difference. As to the BBC not having oiling problems, yes they did. Back in 1991 with the MKV & later the MKV1 the oil system was finally changed to a much better system. All new BBC's built today by Chevy use the new oil system.

 

Wish you were closer. You sound like the guy I need to fix this engine. Almost worth hauling it down there.
Gary

 

I'd be interested to know what the changes to the oiling system occured in 1991.
Dave

 

Dave with the MKV change a third oil galley was added beside the cam to give oil to the mains and the side oil system was eliminated. The MKV & MKV1 both share the changes which included a new filter pad and duel pressure reliefs for the filter and the built in bosses for an external oil cooler system. I would think google might help find a view of the new system. I should add that even the cam bearings are now installed with the oil holes facing off to the side. I'm a Ford guy and it's fun bringing my Chevy buddies up to speed 10 or more years after the fact. When they stop by the shop ,I here" when in the hell did they change that"!!!

 

interesting, I've never been in the lower end of a big block made in the past 20 years.

 

Thanks guys. I've got a guy in Marysville building me a whole new engine from the original engine. I'll deal with the one I took out when I get around to it.