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I've heard some stories of people spinning bearings, and I certinaly wouldn't want that to happen, but what do you usually need to replace when you spin a bearing?

Is the block all shot up? Oil pan have large holes? Top end destroyed?

Also if the timing chain snaps, does the engine kill itself, or is it protected somehow? (And do timing chains really ever snap?)

96m6lt1

a spun bearing usually hurts the bearing,i have seen a few that hurt the rod as well causing replacement or resizing of the rod,if a main goes it can do damage to the block in which case you will then need to have the crank mounting surface ALIGN BORED this brings it back to its normal geometry,in the 18yrs. of hot rodding i have,this has happened 2 times and a 3rd being 2months ago in my z28 @112,000 heavily raced prior to me and blown headgaskets no worries a new engine will be in this week..still sux!

mmmchickenboy

most, if not all, American engines designed with the camshaft in the block are NON-interference motors, this means that the pistons will NOT contact the valves, no way shape or form. most modern imported overhead camshaft engines are interference which means if the timing blet/chain snaps(or slips) the pistons will contact the valves and damage will occur. a timing chain might slip if its worn enough, but snapping is a rare occurence. timing belts are much more likely to snap/slip.

96m6lt1

lt1s are commom for broken chains due to high RPM,the lt4 hd chain is a good stock replacement....

96camaroz28lt4

I spun a rod bearing and the bearing was bad, warped the crank .040 and bent a rod.

hotrod18_69

Yup happened to a buddy of mine, he bent 3 pushrod and valves.

cat1055man

What causes the stock GM timing chain failure? I just changed my cam recently and replaced the chain and sprockets to be safe. The original looked good at 30k, crank sprocket had minor wear on teeth. I ran up to 6200rpm frequently, 1.6 rockers ,crane dual springs. Did the failures mentioned in this thread happen at high miles or was the application more severe, very high rpm or high spring pressure?

1racerdude

Did you increase the spring tension?
You should have got the LT-4 ED Cloyes chain.
Sometimes the two sprockets don't line up.If viewed from the side one may be out farther then the other or not on all the way causing the chain to run at an angle. Will break a chain in short order.