I have been reading more and more posts about people spinning bearings shortly after their cam install. WTF!!!! I am putting a new cam in soon (224/230) and would prefer not to blow the bottom an hour later. What's going on here? Should I be worried cause I am?

Brad

 

You're probably referring to that recent thread. I think it can happen to anyone, really, but people without any mods aren't posting it on here.

Like I said there, I spun 2 bearings without so much as an air filter at 70K miles. Not exactly high miles, and not exactly a cam. It happens.

 

Usually sloppy techs and inexperienced modders get dirt in the engine (a lot more than they think) when they put in a cam and then that dirt, bits of rag, etc. get sucked into the oil pump and distributed all over the engine. People use Abrasive scotchbrite pads to clean the surfaces of the heads and block and spray bits of scotchbrite all over the inside of the engine. In my experience, the most likely cause for a spun bearing is wear (either premature or normal) or excessive RPM.

 

Theres always that risk of spinning a bearing when you open up the motor to swap cams.. you allow a lot of dirt and crud to get in there. If you have taken care to change the oil every 3k miles and dont have sludge built up anywhere then i say the chances of spinning a bearing are pretty slim. After talking with a guy who knows quite a bit about assembling a motor, I have learned these things dont happen very often and motors can take a lot more abuse than you think. in fact when i pulled my cam out I noticed one of the journals was scored all the way around deep enough to grip it with your nail. after asking the guy about this he didnt seem at all worried about the condition of the bearing and said it was not a big deal at all.

 

Yall are making me scared to go crank my car.

I just installed a cc306.

 

As mentioned, dirt dirt dirt. Unless you actually have the engine out, it's very hard to keep things clean as they need to be. I'm like a surgeon when it comes to the engine. Keep things clean and there will be one less thing to go wrong.
Another major issue is the fact that you have bearings with 85k or so on them most of the time if not way more, then you sling in a brand new cam. Those bearings already have a wear pattern. Putting in a brand new cam can accelerate that wear pattern as it adapts to the new cam.
You can also nick the bearings installing the cam if your not careful. Thats bad news. I actually pulled 2 bearings after building my last engine just to be safe. Sure enough, the ends were nicked cause I was tired and trying to get things done, and got a lil sloppy.

-Shannon

 

Yup. I suspect that's what happened to mine even though a professional installed the cam.

I had the same cam inspected and polished before it was installed in my new short block (out of the engine bay. I expect (hope) that it will last as long or longer than a factory installed stock cam. Had new lifter installed at the same time.

 

Yeah I'm keeping things pretty clean during this cam swap and probably won't mash the gas for a couple of months of regular driving after the install to ensure a very broken in motor and parts. Hopefully with 52K on the clock I won't do any more damage than the broken timing chain caused when she finally fires up. I feel a little better.

Brad

 

It's easy to damage the bearing when installing a cam, especially when you are working in a confined, dirty space (ie when an installed LT1). Be careful, take your time, and be very clean!

BTW: I have been there/done that though not on an LT1.

Rich Krause

 

I can see spinning a rob bearing possibly due to the dirt problems mentioned and also due to the fact that the engine is making more power (tougher on bearings) and is probably being shifted at higher RPM than before the cam swap.

To eliminate these problems, slightly less RPM (do not overcam and make powerband too high) and cleanliness will be two helpful things.

And yea, those scotchbrite pads are tough on bearings. Most dealerships do not allow the use of them for this reason.

NightTrain66

 

I replied in that other post. I thought I had a spun bearing but now I think it was just my timing set desintigrating.

 

what exactly does a spun bearing sound like?

 

knock knock. Who's there? Spun. Spun who? Spun Spun and soon no run.

 

sometimes a knock and rod bearings sometimes make a "chirping" sound.

NightTrain66

 

Well I just realized that i've had a blown head gasket since i got my car. The oil and coolent are mixing. I drove my car for 1000 miles after i bought it then when i did an oil change i realized it was all F***** up. Should i be safe just doing the head gaskets or will i need to rebuild the bottom end because of the increased wear on the internals?