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Discussion Starter #1
Well the crank came through my timing cover last friday. it was funny it happened at about 2000 rpm pulling out in traffic leaving work. oil pressue was all normal and no warning just came appart. Now Im in the middle of an unscheduled build but its all good because Im improving on what I did 6-7 years ago adding a main girdle is the first on my list and a new cam, t sump canton pan, a good balancer and alot of new extras. so farwell to my 306 who has served me well you had 80-90k miles of hard playing. ( taps playing in the back ground)
 

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Main girdle will do you nothing. Main studs and a line hone will do much better on a 2 bolt block. As well as a 28oz or internal balance crank.
 

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I find it hard to believe you didn't feel a 30 pound chunk of metal working itself loose. There had to have been some sort of vibration.

when my old motor ate all the main bearings, the damn car shook like crazy at anything above idle.

I would be more worried about figuring out why this happened.
 

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Discussion Starter #4
Yeah I have the main studs and getting machine work done on my new used block
What about the 28 oz balancer the stock is a 50 oz.
As far as vibrations before this happened not a thing other than the f303 cam
In the car it was running great I still have to take that one apart and see what went bad
 

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28oz is better than 50oz, but the entire assembly has to be 28oz. Meaning you'll need a 28oz crank, balancer, and flywheel. If it just let go at low RPM out of nowhere, it wasn't cap walk that killed it most likely. Sometimes cranks just fail after a while.

Make sure the machine shop line hones the main bore with the studs on.
 

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28oz is better than 50oz, but the entire assembly has to be 28oz. Meaning you'll need a 28oz crank, balancer, and flywheel. If it just let go at low RPM out of nowhere, it wasn't cap walk that killed it most likely. Sometimes cranks just fail after a while.

Make sure the machine shop line hones the main bore with the studs on.
why with the studs on ? whats the difference.
 

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Because the studs have more clamping force than a bolt. They will distort the main bore slightly because of this, so you have to re-line hone the main bore to get it concentric again.
 
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