What exactly is a "spun" bearing? What causes it?

June 10, 2021, 10:40 AM

Curly1

quote:
Originally posted by 183N:

This exactly. A few years back I learned the hard way that a dragster needs a billet oil pump. At about 700’ into a run it felt like the engine “tightened up” and nosed over. I immediately took my foot out of it and shut it off. When I took it apart the melling pump pickup was laying in the pan. #1 journal on the crank got hot but luckily I clicked it off before any bearings spun. Had to turn the rod journals .010, put it back together and the crank broke at the first journal 60 passes later. No doubt due to being turned.

Now all three of our engines have Moroso billet oil pumps.

That was one thing that always worried me about Hoosier tires. The tire shake was brutal and I did not want to break oil pump.

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"Dunning-Kruger Effect"
-a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge.

Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue.

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June 10, 2021, 11:08 AM

183N

quote:
Originally posted by Curly1:
quote:
Originally posted by 183N:

This exactly. A few years back I learned the hard way that a dragster needs a billet oil pump. At about 700’ into a run it felt like the engine “tightened up” and nosed over. I immediately took my foot out of it and shut it off. When I took it apart the melling pump pickup was laying in the pan. #1 journal on the crank got hot but luckily I clicked it off before any bearings spun. Had to turn the rod journals .010, put it back together and the crank broke at the first journal 60 passes later. No doubt due to being turned.

Now all three of our engines have Moroso billet oil pumps.

That was one thing that always worried me about Hoosier tires. The tire shake was brutal and I did not want to break oil pump.

Yes!! I had Hoosiers at the time. MT on both cars now, much smoother when the tires hook at the end of the burnout.

June 10, 2021, 11:17 AM

Alaskaracer

quote:
Originally posted by TheBlueTruck:
quote:
Originally posted by Coloradoracer:
I was running King Hp mains, never an issue. Rods were King XP bearings. Was running them because I had mid ordered so figured they would be ok. Other racing buddy was running the same. Turns out they were delaminating then would "grab" the crank and at that point it was game over. That was my third pass on those bearings. My buddy was getting about the same, 3-5 passes before boom. King HP never an issue.

XP as in the coated bearing?

Yes.