KenP

I installed heads/cam etc... on my stock block back in 2000 and 20,000 miles later I am far from being SORRY... . You should refrain from making blanket statements (quotes) as this one, as it is not true for everyone who upgrades their heads/cam.

Sorry about your luck.

SloLt1Z

The spun bearing is actually supposed to be kinda of common on lt1's after a head/cam change, it was mentioned in Gm High Tech before, though I have seen at least 10 go good and no problems ever being metioned, even after years of hard running. Sorry to hear about your bad luck, but to say to will happen to everyone is just incorrect.

5.0THIS

While it is true that adding more power will bring out any weak points in a motor at a much quicker pace.... it doesnt mean that all cars have weak points such as yours, which will cause a failure after a h/c install

J's 82

The LT1 is simply a small block chevy, nothing unique.

many variables at work here,

you did a cam change on a 105.000 mile engine..

did you drain the block or let coolant get everywhere?

Was it your first time? Did you keep it clean? I mean operating room clean? I used over 50 pairs of rubber gloves and numerous lint free towels working on mine.. so "clean" is a relative term..

The variables coincide to cause a failure, high mileage, stock bearings, high rpm wear and stress (with the new valvetrain), possible dirt intrusion during install..

Sorry for the engine but at 105k it may of been better to save and then spring for a new shortblock to make the mods last, even if you didn't spin it so early.. not to assume the LT1 can't last or be beat on for many miles just imo it would be best to start clean at that mileage than spend mega bucks on a top end to go on a worn bottom..

I did a h&c swap on my LT1 4k miles ago, it has 60k on it now and is running fine with a cam in the 230/240 range.. I had a bit of trepadation after reading all the spun bearing posts but after talking to a few people decided to go ahead with it, the data gathered from these people was not so scary, most of the time dirt causes the problem, next high mileage, last high rpm.. at 56k I considered it a mileage to do it, over 80k and I would of just added nitrous until the bottom gave out..

I think if we actually did a poll as to who spun a bearing after cam install and who didn't the numbers would show that a small number of people actually have this problem they are just more vocal about it.. I had done numerous cam swaps on non-lt1 engines but the posts had me worried, as it turns out it is just an engine, not voodoo science or a poorly constructed boat anchor that warps when you torque it..

Kory 88 Iroc Lt-1

I'm sorry for your misfortune. Blanket statements make you look foolish. There are few absolutes when modding cars. Your theory isn't one of them. I have had the heads off my engine 2 times and changed the cam once. no problems in the 8000 miles I've put on it since then.
Kory

MTL_Z28

This thread is just what I need right now, with the heads and manifold off currently being ported, and meanwhile my mechanic is swapping the cam on my stock bottom end motor

grygst76

Out of every cam-head swap I've done in my life on various high mileage and low mileage motors---I have never spun a bearing I may have spun rod bearings, but that was my own negligence and spinning WAAAYY past the motors redline.. Blanket statement--like saying If you put a C.A.I on your car you screw up your MAF sensor because of the extra air..

Ai

Of all of the customers we've had with LTx's (since that seems to be the group who feels this is a problem), no one has spun bearings immediately after a head or cam swap to my knowledge.

Rev is spot-on, most people don't realize how serious a lost head gasket can be and will drive until they're somewhere convenient to stop. Aside from that, don't take offense, but it's primarily young people who own these cars and do modifications to this extent, and for many of them it is their first time. Quite honestly, I am surprised how few people spin bearings after cracking engines open in filthy bays, makeshift garages, etc.

Good luck with the upcoming rebuild

-Phil

dnz28

honestly most bearing failures=dirty installer.

turbo_Z

I believe most people spin bearings because they abuse their motors after the cam swap... not necessarily because of extra dirt and debris. My cam install went fine and after a good 10k miles I still have great oil pressure and no problems to speak of but my motor did look very clean to begin with which also plays a big part in cam swap success if you ask me. I actually helped a guy install his hotcam a couple months ago and the shop was filthy as well as his motor but everything went fine and it still runs great to my knowledge so I just dont buy the extra dirt theory.

Smokn '94 Z

Well I too must be one of the good, unexpierienced, lucky head and cam swap guys... I am lucky I guess. The only thing that I think will cause me to spin a bearing on my 88,000 mile short block with heads and cam is my right foot. Sometimes a car/engine has just seen its day. 105,000 miles are a lot of miles and who knows how the car has been maintained over those miles. Be clean and change the oil regularly and those bearings for the most part should be o.k. IMO. Were you the original owner of the car? The only thing that broke after my heads and cam was my eaton posi powerd rear end!!

94 CAMRO Z28

I did a cam swap on mine (hot cam) at about 80K miles. Im now up to 101K on the ticker and still going strong.

Aaron

90 Z28SS

I've had a Hot cam and cc306 in my stock shortblock over the past 2 years and countless 6800 rpm blasts . 110,000 miles and still going strong

disco192

I really hate to break it to you.... but you either screwed up or had crap for luck. It is NOT a case of common occurances. You hear about it most often on head/cam swaps because they are the most involved things that most of us do ourselves and some people just take shortcuts. I put the heads on my car and I didnt cut ANY corners. That was after i swapped the head on my saturn and blew it up... lesson learned.

There are many things it could have been. Maybe you didnt torque the heads in order, 3-4 times. I torqued them down in 5 stages to make sure. There are a million things you could have done wrong, who knows... thats just the 1st thing that comes to mind because of the block shifting theory.

S.J.S.

I agree with everyone here...everyone has a good point and I think the original poster is very frustrated. It has to do with a lil luck too. My motor spun bearings at 79K and all I had on it was a K&N and pullies. I don't think anyone can say for sure what exactly went wrong, too many variables. Dirt, builder, 100k+ miles, coolant, like I said, just plain bad luck. I don't think anyone should be criticizing you either.

Good luck on your rebuild dude.