This is very interesting. So the next question, is why are these LT1s eating cam bearings? I don't think older small blocks do it, I've torn down tons of them, and a lot of the time you could just leave them in, even hi mileage engines.
I wonder if Greg has a point about the water pumps, is there some way the stock one can put a side load on the cam?
Or is it possible that the procedure GM uses to install them on these newer engines is halfassed, meaning they are not getting them as straight as they should in the beginning?
does everyone spin their cam by hand after the install and verify that they turn nicely as they should?

 

I remember you have had yours for some time like me. I really toyed with the idea of leaving it alone, but thought "that always happens to the OTHER guy". What a huge mistake.

 

I would really like to know what's up with this.

I did my heads / cam swap two years ago this December. It was my first time swapping a cam, and I'm definately not race-mechanic material... yet I had no problems. I didn't prime my oil pump either on installation... just turned the motor over a few times without the coil to get oil pressure.

When I did my swap, I did it ***-backwards... took the heads off, then took the cam out. Put the ported heads on, then put the new cam in. Maybe that prevented this core-shift bearing/block warpage voodoo?

There has to be some explanation... not necessarily GM quality-control related, but more like a subtle thing that happens in the way people are doing their swaps.

 

I'm still yet to have a problem w/ my car.. And I've swapped out cams numerous times in this current motor 224/236, CC306, 230/236, 233/242, and I've got an LE2 waiting to go in very soon - possibly this w/e. But, why so many others have the same problem over and over.. Shrug.. I dunno.

Maybe it's the fact that I'm not running factory GM bearings anymore? The block's a 357 now.. So...

 

That would be interesting...there has to be some coorellation to this. Too many happen for it to be a coincidence each time, or every person that installs it messes up a cam bearing, or being dirty. I will be the first to say:

No elec. water pump - spun bearing

Anyone else?

 

I am not trying to slam anyone just a couple points of view from 35 plus years of doing my own wrenching from everything ranging from lawn mowers to porsches to keeping a 350K mile lincoln running. I have been a chevy man my whole life an my very first car was a 63 impala SS with a tired 409! Anyway.

The attention to detail is very important when doing anything to a motor. One common thing i see here and remember this is just my point of view, is that people tend to do head and cam changes after some diaster as already happened like a blown head gasket. Which i am sure crapped out the oil and put some undue stress on the motor. Spinning any bearing after a cam change says to me that the motor was already weak in the bearing department and with the new cam you are driving it harder and all that the cam change did was bring out the weakness. OR during a cam change lots of debri got knocked into the motor and sucked up by oil pump on the initial start and starved the bearings if only for a short amount of time. I think the notion of a cam change trashing a motor is not accurate at all. With the LTx motor the waterpump drive is in fact driven off the cam. But the any extra loading that has been taken care of by a pretty robust bearing is in the block. Initial startup on new parts may be a factor as well. By that using the proper cam lube and lots of it. Yeah it is messy but so what. From my personal experience if you get lube with a cam kit it is never enough. My personal favorite engine building lube is good old STP. Sticks like glue and wont run off the parts. But that is just me. If i am doing a cam i use one whole container just on the cam and lifters and another 1/2 on the rockers and the remainder on the cam chain set, but again this is me. I know one egine builder that swears by white lithum grease. Personal preference but you get the point. Plenty of lube. Care when putting in the cam to protect its bearing surfaces ant those in the block are important. Think of your engine starting dry for 15-20 seconds. You got the manifold off, why not prelube the engine right before you bolt on the intake? This is not ment to be a rant or a slam just an observation. There are plenty of LTx's out there with 150k plus on them. I dont think it is fair to blame a spun bearing on a cam install because by doing that you are really blaming it on yourself. Hell i had a buick that the water pump was leaking, not to bad, replaced it and within 100 miles the fuel pump took a crap. So would it be valid for me to say the WP replacment caused the fuel pump to go out?
I very much enjoy this forum as it is a great source of information and also a great source of thought provoking posts as well. I personally have changed 1 cam in a 55K LT1 and it is still running 4 years later with 125K on it now. That don't make me an expert for sure. Just my 2 pennies, well maybe 3 in this case.
Keep the posts flying!

 

Good post 944.

I like plenty of lube on my journals and lobes too. Don't care much for STP but Clevite Cam-guard is a great product for new bearing assemblies. Designed with cold-start conditions in mind.

I do think the extra loading from driving the waterpump plays a part in the wear. I can't see how it wouldn't... especially on the front journal. New bearings throughout and it'd probably run another 100k plus, but putting a new cam on old bearings.... hmm, maybe not.

Cleanliness is next to godliness with engine stuff. Dirt is the #1 bearing killer so any time I work on something internal to an engine.. I run a high detergent oil and change it and the filter after 100 miles. Then go back to synthetic. But this is just the way I do things.

-Mindgame

 

You make a lot of good points 944. I did have a very reputable shop put in the cam so I really don't have any answers. I guess I will know much more when I tear down the motor.

 

birdman1,
The factory cam brgs are just good enough to do their job in stock form.The water pump put's a very big load on the front brg.With the addition of heaver valve spring's and more lift the brg's can't take it.Some get away with it some don't.If I had to guess,I would say that the engines that do make it have a different kind or grade of brg than the ones that don't.

 

I lubed up the lobes with ARP assembly lube, but the instructions told me not to use that on the bearings, so I just put some motor oil on the cam where it goes into the bearings. To me it looks like the assembly lube would be too thick for the bearing journals. That might be one of the problems.

 

2000+ miles on mine.
heads came off 1st, then cam came out. new cam went in 1st then the new heads went on

i poured 2 quarts of oil into the lifter valley before the intake got buttoned down, then put the other 3 in thru the heads and ~half a quart in the filter.
i didnt use any cam lube at all, just good ole new 5w30 motor oil on the journals and lobes, just kept pouring it onto the camshaft as i slid it into the block with a bucket underneath to catch the excess oil
i didnt prime the motor, just after all was buttoned down and ready to go, fired it up like i normally would on any given day

also switched to a CSI pump

80,000 mile stock bearings that now have ~82,000 miles on them with the new valvetrain

not that the above has any technical merit but i thought i would share how i did mine

 

I swapped cams a year and 21K miles ago still run the mechanical WP. At any rate here are my thoughts on this.
Just use oil as a lube, this is a roller cam so no breakin and no breakin lube is needed and the lube could clog tight clearance oil paths.
The water pump probably does contribute to front bearing wear.
The heavier springs used with our roller lifters probably also stress the bearings.
The ever popular 5w-30 M1 is a bad choice for the LT1 and will lead to higher wear than necessary, how many of you that had a problem were using it.
In car swaps can be tricky to get the cam straight even on a b-body with it's cavernous engine bay I imagine it even tougher in an f-body, could easily do harm here.
Dirt or gasket bits, I know the timing cover gasket on mine was like cured epoxy, in all the efforts needed to clean that off it would be easy to let some crap get where it should not be.

Now by the no breakin I did not mean beat on it immediately, drive it easy and change the oil and filter often for awhile to flush out any dirt and to allow any problems to reveal themselves under part throttle not at WOT.

 

That would be interesting to see for sure. I swapped to a electric WP at the same time as the heads/cam swap and have had zero problems in the 35-40k miles since.

-Tony

 

Whats wrong with mobil 1 5w30? I always use 10w30 m1.

 

Of course, I am told after my engine took a sh#t that I should not be running 5w30 in Texas during the summer due to the heat. Mine came with 5w30 from the factory so I thought that is the way to go. What a big mistake.