Well.....something went very bad. Not sure what yet, but we have 4 broken connecting rods. The other two are bent.
Two of the rods went through the block.
One of the wrist pins with a piece of rod attached was in the pan. It ripped the wrist pin right out of the piston. The piston is wedged in the cyl. In fact all of the pistons that are disconnected from their rods are twisted in the cyl. All broken rods show the same twisted format.
All cyl. walls are either cracked or missing part of the cyl.
The camshaft is in at least 4 pieces. The rear camshaft "freeze plug" is gone. I think the back half of the cam pushed it out. Both #6 area freeze plugs are blown out. One in the bellhousing, one on the return road.
Timing chain is OK. Oil pump was still attached by one bolt. The other was apparently hit by #1 rod and it was in the pan along with pieces of the block.
Spark plugs look great. No signs of detonation, no damage whatsoever.
Fortunately, no obvious damage to the aluminum cyl. head. No valves touched a piston. No bent pushrods.
No apparent head gasket leaking.
How it happened:
I was warming it up for Kelly by driving it around the pits. I went all the way down the return road, made a U-turn and stopped. Checked all gauges, everything normal and engine is coming up to temp. I think it was about 140 degrees. Started to roll down the return road. Shifted into 2nd and pushed the thottle down to around 3/4. I wasn't floored. It came up on boost, I noticed the boost gauge swing past 5lbs. then BOOM!
It didn't rattle at all. I would guess the BOOM occured somewhere in the 3000-4000rpm range.
We haven't fully dissassembled the motor yet. The only real "clue" thus far is #6 piston top compression ring is out of it's groove and bent into where the missing cyl wall used to be. So this ring bent when the piston was still moving up. When we pulled the head this was what we saw in #6.
Here's a pic of #3 & #4.
A pic of #6, #5, #4 (L to R). NOTE the rods.
And here's the window'd block.
If you want to see these pics in full size go to http://www.cardomain.com/ride/686815
So any idea what the hell happened?
Anybody have another 250 built short block they want to sell?
I guess we'll just have to build it stronger!
Later,
Will
Two of the rods went through the block.
One of the wrist pins with a piece of rod attached was in the pan. It ripped the wrist pin right out of the piston. The piston is wedged in the cyl. In fact all of the pistons that are disconnected from their rods are twisted in the cyl. All broken rods show the same twisted format.
All cyl. walls are either cracked or missing part of the cyl.
The camshaft is in at least 4 pieces. The rear camshaft "freeze plug" is gone. I think the back half of the cam pushed it out. Both #6 area freeze plugs are blown out. One in the bellhousing, one on the return road.
Timing chain is OK. Oil pump was still attached by one bolt. The other was apparently hit by #1 rod and it was in the pan along with pieces of the block.
Spark plugs look great. No signs of detonation, no damage whatsoever.
Fortunately, no obvious damage to the aluminum cyl. head. No valves touched a piston. No bent pushrods.
No apparent head gasket leaking.
How it happened:
I was warming it up for Kelly by driving it around the pits. I went all the way down the return road, made a U-turn and stopped. Checked all gauges, everything normal and engine is coming up to temp. I think it was about 140 degrees. Started to roll down the return road. Shifted into 2nd and pushed the thottle down to around 3/4. I wasn't floored. It came up on boost, I noticed the boost gauge swing past 5lbs. then BOOM!
It didn't rattle at all. I would guess the BOOM occured somewhere in the 3000-4000rpm range.
We haven't fully dissassembled the motor yet. The only real "clue" thus far is #6 piston top compression ring is out of it's groove and bent into where the missing cyl wall used to be. So this ring bent when the piston was still moving up. When we pulled the head this was what we saw in #6.
Here's a pic of #3 & #4.
A pic of #6, #5, #4 (L to R). NOTE the rods.
And here's the window'd block.
If you want to see these pics in full size go to http://www.cardomain.com/ride/686815
So any idea what the hell happened?
Anybody have another 250 built short block they want to sell?
I guess we'll just have to build it stronger!
Later,
Will