spun bearing? I think, little play SBC 5.7

Also, rod side doesn't really matter because it should be stationary.
 
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Its Smooth with fingernail trick lol
 
When a bearing spins, it eats into the rod, so it wouldn't take long before it spins again. The rod needs to come out and replaced or (and this is what they do to most rods when doing a rebuild using the original rods) take it to a machine shop and have them to clip both the rod and the cap, and then hone it back to"round" and correct size. Not the right way but the crank needs at the very least polished like what was mentioned earlier in this thread.
 
Polish it up, buy a stock bearing, and send it.
 
so guys go easy on me....
I'm wanting to understand what causes this? Like how can cylinder 8 spin a bearing and all the others, especially 7 right next to it on the same crank journal, still be perfectly fine? For that matter, how come usually only one rod spins and the others usually from what I'm reading/gathering will not? Now I'm just wanting to learn what causes this since apparently it's a pretty common issue among these SBC motors. thank you
 
skyhighZJ said:
The fastest way is to just focus on the crank, slap a bearing on it run 15w40 and send it to the moon. Either way that motor is living on borrowed time.
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I'm very well aware this isn't the "right" way to fix it...I'm still gonna get that other motor from a friend but I want to put it on a stand, go through it completely before going through all the work of swapping so I'm just trying to get this one to allow me to play on sundays couple times a month for a while until I get the other motor ready to drop in.
 
marty79 said:
so guys go easy on me....
I'm wanting to understand what causes this? Like how can cylinder 8 spin a bearing and all the others, especially 7 right next to it on the same crank journal, still be perfectly fine? For that matter, how come usually only one rod spins and the others usually from what I'm reading/gathering will not? Now I'm just wanting to learn what causes this since apparently it's a pretty common issue among these SBC motors. thank you
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It's not a SBC thing. It's an "any" engine thing. Just like all of the 4.0s you've rebuilt over the years. Just in a V as opposed to straight.
Dirt or debris can get in there for one thing. Poor lubrication too. Among other things.
Crocus cloth is typically 1000 grit.
 
Jody Treadway said:
Dirt or debris can get in there for one thing. Poor lubrication too. Among other things.
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I guess I was wondering if there was a "specific" reason this usually happens among just one cylinder. I personally find it so odd/weird that it's just one lol, like I'd understand better if they all did it, but when one goes it's like wth why
But I suppose for my current needs I'm glad it was just one and not all. I've got a new bearing set coming tuesday so I've got time to pull all the caps, polish that one the best I can and get this thing together and back in the woods. Now that winter is here, there are some trails needing clearing and cutting hehe!
 
btw, since I bought this tahoe with a "race tune" PCM, it redlines at 6400ish...like wth, I'm not a v8 guy, don't know them but I've owned 9 Tahoes, 3 Suburbans and I know these motors redline at 5400rpm so did that play a role in this possibly? I can't promise that I haven't had it revving in the 6000+ rpms a couple times haha, but now I'm wondering if that's what gave way to this happening???
 
Either that or the race tune caused it to "spark knock"/detonate on Cylinder 8 too many times?!? and that caused it to prematurely wear the bearing?? I'm sure it can't be good for any engine to put around mostly a low speeds when burning stupid rich lol
 
skyhighZJ said:
High revving would cause other issues like bent connecting or push rods. Spun bearing is almost always trash in the oil causing extra frictional wear causing gaps = spun bearing.
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well I guess trash in the oil it is.
so does a tune allow a motor to rev up another 1k rpms?
 
Crocus cloth is similar to 1500-2000, vastly different from Emory cloth. It’s for polishing not removing material.

It’s like $11 for 1” x 30’ roll.

Bearing problems are always an oil problem. Only related to rpm if you don’t have 10psi per 1000rpms. So at 6k rpm’s need at minimum 60psi.

But if using cheap oil/filters or dirty oil etc this can wipe a bearing quickly.

The oil pressure keeps the bearings from actually touching the crank journal itself.

Bearings spin when they touch and gall onto the crank and then spin with the crank.
 
Mac5005 said:
Crocus cloth is similar to 1500-2000, vastly different from Emory cloth. It’s for polishing not removing material.

It’s like $11 for 1” x 30’ roll.
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napa? so it will say Crocus cloth and it's one set grit rating? (that's what I'm gathering)
 
LBarr2002 said:
Any tune can adjust the Rev limiter, doesn't mean it's a good idea. I can't remember, are these plug and tune yet, or were they still swapping chips?
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didn't know you can set rev limiter with tune, learned something new lol. This is the whole ECU not plug and play. Anybody want one LMBO.
I will say though, when i bought the Tahoe, was lifted on 35s with 6" lift, 2 door, 5spd and long tube headers with Flowmaster exhaust and with factory gears on 35s, it would def boogie down the road so I guess for street chevy the ECU has some power output for sure but for my uses, I could care less.
 
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