MoeMonney

I recently purchased a 3.4 crank for my rebuild and some people told me to never lay it on its side. Although Im not the one directly building the engine I sent it to be measured and its straight as an arrow.

Any thoughts on this?


Thanks!

Sula

My thoughts incline toward the notion that a crank that can't stand being laid on its side isn't one you want in your engine.

But I'll await better-informed views.

jaetee

agree....

dkraige

I suspect somewhere in its journey from manufacture to your location, it sat on its side somewhere. So it's probably already compromised

charlieaf92

When I rebuilt one of my previous cars engines I'm sure I had the crank on its side plenty with no ill effects. It lays horizontal in its finished installation as well. Maybe people who have said that were confused and thinking of plasma TVs.

okbarnett

never lay a crank down

Mike Murphy

Apparently a bit of poking around on other forums reveals that it can be true - a crank can bend over time.

I think a lot depends on how it's stored and what it's actually resting on. If you lay a crank down on its side on a concrete surface, you could easily damage a journal. Apparently folks have reported a bend in a crankshaft after it was sitting for a long time.

charlieaf92

After doing a bit of research there is a sound argument for not storing one on its side for any extended period. I think its a stretch to insinuate that it would be ruined by laying it down for a short duration though. This is going in a normal car, not the space shuttle. I don't think the tolerances are critical enough that a few out of place atoms will be detrimental. That being said, no reason to risk it. Just store it on its end or build some wooden stands to support it along the points where it rides on the bearings.

relinuca

Way "back in the day", critics of Henry Ford's 60hp V8 said the V-config would result in oval bore wear.

relinuca

Sula

Plastic deformation of steel? Googling suggests that this begins at temperatures around 600C.

If you keep your garage thermostat in a reasonable range, you should be okay.

Mike Murphy

I'm just saying that there's tons of forum posts on this and everyone is weighing in for or against with no real science. Someone suggested a perfect case for Mythbusters. I also found someone suggesting that this is a"very basic bridge-esge statics problem"

Source here: https://grassrootsmotorsports.com/fo...s/27724/page1/


"You have force acting on the system, gravity and crankshaft weight, acting in the center of the unsupported span, middle of the crank in this case. Then after a bunch of seemingly trivial math, based from you force diagram, you end up with how the forces are acting on your object. Then after some more math, involving material strength and thickness, you end up with either something broken or holding its own just fine, but bending in the direction of the force applied.

Easy visual is to use a piece of string and a significantly weighted nut. Place the nut in the middle of the string, then attempt to pull the string taunt horizontally. You will see that the nut always droops a bit even though you have the string to the point of breaking. Eventually, your crankshaft will do the same. Reason is the unsupported span doesn't have either enough mass in the vertical direction to avoid the deflection or doesn't have enough mechanical properties, total material strength or already deflected in the opposite direction, to resist the deflection either."

extanker

a thread about the block bending if left on an engine stand went on for a few pages......mostly by our inhouse engineers ........some times the entertainment value here is priceless...........engineers ....ninja pleeezzz

thebowl

The essence of the internet revealed and placed on display, all in 12 posts...

jandackson

Uh this isn't how the physics works. The crank would have to go through plastic deformation in order to bend and stay bent after it was removed from its horizontal resting position. As stated above, the crank would need to be over 600F for that to happen with gravity as the force.

Entertaining stuff, though.

KoB

If you are truly concerned, my recommendation would be that you get a rotisserie motor and build yourself a Crankshaft Storage Device. If you live in an area with an unreliable power grid, you may want to consider UPS or solar backup.