5.7 with a broken crankshaft

:banghead: the motor in my 1990 g30 broke the crankshaft in the 2ed motor in 10 years.can i just order a new crankshaft from summit or is it something i need a machine shop to do?it broke right behind the harmonic balancer.and it broke there in the last motor to.last time i just put a jasper motor in it this time i am trying to do it on the cheep if i can.

You can certainly install a crankshaft yourself. Pull out the engine and put it on an engine stand. If your going to try it without pulling the pistons make sure you put rubber boots on the connecting rod bolts and have eight kids to hold them in the proper position.
First you need to put a straight edge on the bearing supports and make sure you don't have an alignment problem. Basically you have somesort of problem and it needs to be fixed. Either a plugged oil hole or alignment problem.
Otherwise get a rebuilt shortblock from a good machine shop or take your block to a machine shop and have them check it out. They sell crankshafts that have been turned .010 which are cheaper than a new one.
A machine shop might loan you a straight edge if you buy all parts from his shop.

being a carpet installer i have a straight edge. but the 8 kids i don't need sounds like a headache to me. i use and old coke box its a lot more quieter to me just add holes in the order you want then in.works for heads to. i think i am going to find a junkyard motor to put in it and then sell it.for the time being i am putting a 83 g20 back together to work out of.:banghead:

In the Atlanta area it is almost cheaper to purchase a short block for a 350 than going the junk yard route. The short block comes with gaskets and a new oil pump. Even getting a valve job at the same time it is cheaper than a low mileage used engine.
Although at U-pull it I think you can get one for $150.00. You have to completely disconnect it and they use a loader with a chain to take it to the door.
The eight kids was a joke about trying to install a crank without pulling the pistons.

crankshaft is ok the harmonic balancer and the bolt broke.i got the bolt out and will have it up and running by the end of the week. had to order a new seal / key / and balancer /bolt and washer.