Cracked Block
09/01/2002
After fully assembling the shortblock and placing the heads on and getting them almost ompletely torqued, one of the nuts on the studs pulled "funny." Backed the nut off, double nutted the stud to pull it out. It was VERY tight. not good. Cleaned the threads and tried reinstallign the stud. It was very tight and would not thread in much. I figured the threads had somehow pulled out of the block (hard to do that with studs.) Pulled all the nuts back off and pulled the head. This is what I found. You are looking at the lower head bolt hole on the #5 (front driver's side) corner.

Top view. Note the crack from the bottom of the deck to the bolt hole, down and back 2 sides of the bolt hole, up to the water jacket, then leading to the front of the block from the top of the water jacket.


Side view. Note the crack from the corner of the deck (visible in top view pic) down the side of the block heading to the oil filer location. It almost makes it to where the filter seats.

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Looks like the block may have been dropped at some time and it just pick NOW to decide to split. if you look at the front edge of the block deck surface there is a small chunk of metal missing. It was painted so it apparently happened before I got the block 2.5 years ago.

I have another stock block, but it is a 302, not a 306, so I will have to have it machined 0.030" over that checked for cracks, etc. and reuse this rotating assembly. I was hoping to have the engine in the car adn running over the holiday weekend, but it looks like it will be another few weeks. :-(