Well I pulled my motor out and was gonna just change main seals and do a little head work. Low and behold I found a busted piston. The block looks good and the pistons looked good also (all but that 1 lol). It has a little chunk out of if right on the edge of the piston. the compression test was from back to front 90, 90, 120 (with broke piston), 90 on the drivers side and 90, 90 , 110, 90 on the passenger side. I am debating on what to do here. just replace the 1 piston that was bad and all the rings and barrings or have a little fun and bore 30 over and replace all pistons and so on but there is a large $ difference between the 2. what would cause that piston to break? detonation? its not fuel injected. it has a carter performer 700 carb and a Edelbrock performer rpm intake and stock junk heads and stock bottom end. o ya and it is a early model 350 out of a camaro or nova.

 

It would probably be cheaper to just pick up another 350 and drop it in.

 

Thought about that also but kinda wanna build a good one. You never know what you are gonna get with a used motor. This one was suppose to have been recently rebuilt and so on and it looks like they did a half a#@ rebuild on it. But if I could find a lt1 or something like that with the harness and computer and so on then a I would have no choice lol.

 

To answer your question about what could cause a piston to break, it would be nice to see a picture of it.

90 PSI is very low for a compression check. Did you hold the throttle open while you turned the engine over? There's no rhyme nor reason to the cylinder with the broken piston having higher compression.

Sure sounds like you're at least going to have to completely disassemble the engine to find out what else could be wrong. That's the only way to know whether or not you should try to fix what you now know is wrong, or if getting another 350 to build would make more sense.

 

This car is new to me so I have no idea what has been done to it. I got it all tore down now and I found a piston from a friend of mine. The block looks good there isnt even a ridge on it. some one prob ran the heck out of it. I am gonna put it back together with and drop it back in. at the same time I got a 93 vortec that I am gonna build for it but that takes money lol so its gonna take some time. at least putting this 350 back in I can move the car around easier and I got a old chevy pickup that needs a motor so this 350 will end up in it.

 

For the record, there's no such thing as a '93 Vortec.