CK5
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HELP needed please

engine is out. #1 piston is broke between 1st and 2nd compression rings. Thats the only piston out so far.
 
Yep, that'll do it.
Now, the question is, is the cylinder damaged?

With any luck, it was just a defective piston, and it didn't scar up the walls. If the wall is damaged but repairable, then you need to do all the cylinders.

I have seen engines with one cylinder bored larger than the others, and they ran well. But I would not trust it for long life.
Back in the day, we ordered a rebuilt short block from Fred Jones for a 371 Ford in one of our route trucks.
I was walking by it sitting on a pallet. Happened to look, and saw 7 pistons marked STD, and one marked .060.
It never came off the pallet.

Our truck engines had to run at least 200K to be profitable. With 300K being being expected.
The old 360s would give good service for at least 300K, we would do an inhouse rebuild, and get another 300k.
By that time the truck was worn out.

Never got that with the 371s. Crappy engines.
 
engine is out. #1 piston is broke between 1st and 2nd compression rings. Thats the only piston out so far.

First off there is only one compression ring (Top ring is compression, second is a scraper ring, and the bottom is the oil ring). Now to let you know what caused the piston to "break" there. That engine has had detonation happening. Detonation will break the ring lands everytime. There is one other thing that could cause the ring land to break and that's if it's a KB piston and the ring end gap wasn't big enough then the rings will grow when hot and the gap will close up and break the ring lands right off the piston. Get a pic up here and I can tell you which caused the problem. :deal:
 
Speed pro cast pistons. .024 ring gap. Cylinder is good. It dosent look like the rings were turning in the bore. Rings are shot!! I think that the piston broke on the dyno. It was pushing oil out of the dipstick tube after we broke it in.
 

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