Had one of those 'wild hair you know where' days and began tearing down my
original 455 (numbers matching block). The cylinders looked pretty clean except for some surface rust in a couple of bores. The head gaskets were pitted, but I'm not sure they failed. Any thoughts? I'll post some pics tomorrow.

 

Post a pic of the timing chain and number of miles/condition as these seem to be the weak link on all the older V8's.

 

Here's some pics of the block after I pulled the heads and also the timing chain area. The big sprocket appears to be laminated steel and I don't see any nylon teeth.

P6071981.jpg

P6071982.jpg

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P6071984.jpg

P6071985.jpg

 

Well, for one it looks like a pretty good layer of sludge. It kinda looks like low compression pistons. Do the numbers on the pad under the number one cyl. match the vin of your car.
The timing chain is shot. There is no plastic left on the factory gear. I'm willing to bet the chain jump a couple of teeth, and no longer ran. I'm thinking time for a major over haul.

Gene

 

The block is out of a '71 Cutlass SX and the the VIN derivative matches the VIN on the car. Not sure when it quit or how long it sat, but a '70 455 from a Delta 88 is in the car now. I assume the dished pistons were part of the move to lower compression ratios in '71. The large sprocket has a GM stamping, but I didn't realize it was missing the nylon teeth. The rotating assembly won't turn, and not sure what else to check for. I'll just continue tearing it down to tank the block and check it for cracks.

 

Nice photos,

Yea, with no nylon teeth left it's hard to tell that they were all gone, the looseness of the chain and the sharpness of the teeth are the givaway. I've seen bad chains but with pieces of nylon teeth still on the sprocket. My 350 is at 80K I'm not looking foward to doing the chain sometime down the road. How many miles on the engine?

 

I'm unsure of the mileage on the original motor, but there's 36,000 on the odometer. I do know the car sat for years before I took ownership 2 years ago. I was real happy to still have the original block, and am trying to figure out why it quit.