How common is it for an LT1 to spin rod or main bearings? I've seen a few posts about it. What I want to know is, those that have, was it shortly after a cam swap?

Frank

 

It's not that common for an LT1 to spin a bearing after a cam install UNLESS, the person is revving the sh*t out of it, or they weren't careful during the install and got dirt in the engine. Not following proper torque sequences would also have some affect as well.

 

I spun mine about 1000.miles after my cam. two mains and one rod, but i had loss of oil pressure. My oil pickup tube fell off , and when i braked oil pressure went to 0.

As for the post above me

You don't mess with the main caps or rod caps, so why would i have to be cairful to torque them properly?? I could understand the dirt thing, but unlikly.

 

Agree with roadtrip, It can happen if, and when you do your cam, but it was probably going to go anyways. Most people spin their cammed motors to 6500 or higher, that is the cause of some spun bearings, if you spin your stock motor that high all the time it will probably spin some bearings. These bearings go out very easily on LT1's so its important to keep the motor clean and make sure you have great oil pressure. Alot of people have had problems with pickup tubes coming off the pumps, me being one of them, if this happens you need to fix it ASAP cause that will eventually cause lack of oil and spin some bearings. But most of the time a cam install WILL NOT spin your bearings!!!!

 

LOL...I shifted my stock motor at 6000, and I shift the CC305/ported head motor at 6000. It hold 70# of oil pressure/cold, and 40# idling/hot.

What I was "fishing" for is to find out if people spin bearings after cam installs because of using break-in lube on their roller cams. I just used 10W30 oil on mine, but it just seems like most spun bearings I've heard of happen shortly after cam swaps. I wanted to know if those people used break-in lube.

Frank

 

I had 3 main cap bearings spin, this is after 6kmiles, but previous owner did the work.

Its been said its due to maybe that when the motor was retorqued, (since it was the first time ever since factory, that it has been taken apart). that it may make bearings miss align.

But generally beating the **** out of it, or poor matience should be blamed first.

Bearings sound like marbles in a glass, soft, thudding. Also it will useually sound towards the front of the motor, but thats due to the sound traveling via the engine oil.

 

About 3000 miles after cam install for me. I have some ideas about what adding a more agressive cam does:

-makes it easier to reach higher rpms
-makes you want those higher rpms more frequently

If your car had many miles on it when you did the install (mine had 92000), bearings are not going to be in the best shape to start abusing them. They may have held up for many miles without the added abuse.

When I pulled mine apart, #2 rod was spun and there was another rod bearing that looked like it may be not far behind. The cam bearings were also pretty spent.

I don't abuse my car, but I know exactly what caused it. I had not really wound it up hard since the cam install and I bounced it off the rev limiter in 2nd gear (I checked my programming and the rev limit was only a couple hundred over stock). I was not far from home and never heard anything bad from the engine, so did not think anything of it.

It was a few days before I drove it again and heard a slight knock on startup, but no noise thereafter. After a trip on the freeway, it was knocking when I came to a stop. Never was my oil pressure abnormal.
Though it was knocking, I decided to limp it home and it was actually quiet other than at idle.

Therefore my recommendations would be to go through the engine if doing a cam swap with higher miles. I know that this view may not be popular and that no two situations are alike. I did see another thread once, that was talking about the same thing [seemingly high occurance of spun bearings after cam swap], so I don't consider it a rarity.

 

I seriously doubt the break - in lube idea, you have to think when building a motor, you do use this break-in lube on the bearings, how would that cause a bearing to spin if you put it on the bearing. It is also a great idea to change your oil after the first couple of miles or 30 minutes or so. This helps get all the grime and gunk out of the oil and filter. And some say that pulling the heads and cam will distorte the block and cause some mis-alignment leading bad bearings, but i dont think ive heard of that theory from just a cam, your really not distorting anything when doing a cam. Main thing is keep the motor clean and dont rev the crap out of the motor with the new found power and you should be fine!

 

Camshaft (moly) lube is different from engine assebly lube. Moly lube has fine grit in it to allow parts to "break in", and create a wear pattern between the 2 parts (IE cam and flat tappet lifter).
Roller cams don't need break in lube, because they don't have to create a wear pattern, but yet, many people still use it on rollers. The extra grit from the moly lube can't be good for main and rod bearings...Especially when it's not neccessary.

Frank

 

Yeah, i wouldnt use break in lube on a cam, that qould not be good. Some good ol assembly lube on the cam would be fine, thats what i use and has worked for a long time! So NO NO on the break in lube, fine particles dont sound good!

 

I was just trying to get a general concensus. I use TORCO assembly lube on my bearings.

Frank

 

I only used oil when I installed my cam. When I did the rebuild I used some Permatex assembly lube on the cam and bearings. I just used oil on the lifters.

 

Doing a rebuild I always used 90w gear oil for engine assembly and have never had any problems, I change my oil after 30 minutes, Then again after 500 miles and 1000 and then regular intervals after that.

 

Why would you not use GM EOS when installing a new
roller cam? It's what the factory uses. I would think that
it's just the ticket, especially since assembly lube is a no no.

 

I spun a crank bearing on #8 200ish miles after my cam install 82k miles............Im glad though, it has since been replaced with a BADASS 383