trax

The second letter on the page, "Bearing the Truth", talks about the possibility of spinning bearings due to torque on the block during a head swap.

MTI writes back that without replacing bearings you should never swap internal parts unless you rebiuld / freshen up the bottom end.

So does this just apply to high-mileage blocks (like the reader's with 180,000) or is MTI saying that all LT1 blocks need bottom end work before changing heads? If that's the case, how come nobody ever says "don't swap them until you freshen up the bottom end"?

KGRESOCK

Weve been discussing this at work. We agree the MTI guys
know their stuff. But were also wondering if this has been
proven out with supporting data.
Very interested in how many people have had this problem.

94formulabz

IMO you are taking a risk with any modification to your car. If it ain't broke don't fix it. What they are saying is that it opens up doors to new possiblilties and their shop chooses not to get involved in situations where something beyond their control coudl go bad and the customer gets pissed. Obviously plenty of people have successfully done head swaps.

I guess you read the recent thread about the possibility of overtorqing the intake causing bearing failure. I have a hard time believeing it but give it a lil more credit if your telling me they published something similar. He was talking about people torquiing them 3x the spec though and i think thats asking for trouble fi you do something that overboard. Anything is possible though and thunderbolts could shoot out of my **** too

Vader

I have not read the article, so I can only go on what has been related on this thread.
The idea that re and re-ing a manifold or heads CAUSES a bearing to fail is ridiculous. There are some reasons why a bearing would fail after that kind of work is done, unrelated to the assembly itself.
First, the use of the small abrasive 3M discs to remove gasket material has been prohibited by GM in a TSB to all their dealers, and for all their technicians to follow. The abrasive dust gets into the oil system, and the particles are small enough to pass through any oil filter made. The dust then abrades the bearings until they fail from extreme wear. The first time I saw someone using those things I thought it looked stupid.
Second, if the heads and or manifold were re and re-ed to install some performance mods, what then follows is an owner thrashing the engine to feel the changes. If the engine has high mileage, and has only the mods done to it, the bearings may fail, just as they would have if the mods had not been done, simply because the engine is being worked harder.
Kind of a cause and effect deal for some people.
Old wives tales and urban myths start in the same way.

speedmiser

Odd. MTI does head/cam cars all the time without going through the bottom end.

llafro

Far be it for a shop to sell you services you might not need to make a buck.

BRAD

atljar

I wouldnt take into consideration the cars mileage, but rather the cars oil pressure before deciding to go throught the engine or not.

pennys58

That's exactly what I was thinking, and I know of people that have gone there for the exact purpose with no bottom end work.