Is this a good deal for a rebuild project???

[knightfire83]

You are correct, but normal wear on engine parts has to be taken into consideration also. Eventually the cylinder bore will wear and create a ridge at the top of the cylinder where the piston rings don't travel up that far. The rings will exspand out and the pistons will seal, but as more wear accurs, the more blow by you will have, creating lower power, smoking, and what not.

All bearings will eventually wear too, but not as fast as the cylinders because the part housed in the bearings is in fact floating on a very thin layer of oil.

When ordering parts it's best to measure the bores and journals to see how much they are worn, as they may need machining. A machine shop can measure everything for you, or you can learn how to use a micrometer.

Sometimes engines come from the factory with over sized bits too, due to production problems. They typically wont throw away engine parts that they can make usable. A .010 - .020 oversize isn't uncommon to find on factory new engines.

As far as bearings. you can also get them in .001-.003 oversize and so on to make up for normal wear, and tighten oil clearances.

If you get a chance to rebuild an engine, I would recommend it. There is no feeling in the world like starting up a freshly painted rebuilt engine that you yourself have created.

[70_F100]

BUT!!!

As far as bearings. you can also get them in .001-.003 oversize and so on to make up for normal wear, and tighten oil clearances.

Bearings are considered an UNDERSIZE component.

Rings and pistons are oversize because the bore is increased.

Bearings are undersize because the crankshaft diameter is decreased.

Just a "point-of-order"...

[knightfire83]

Oops...

That is true... I was thinking since the bearings were thicker.... It's been a while since I had to order bearings.

[70_F100]

That's not an uncommon thought process, even though incorrect.

Just remember that the wear parts (bearings and pistons/rings) are ordered and sized to fit the machined components (crankshaft and block).

In the case of bearings, the inner diameter is smaller (undersized) when the crankshaft is turned. In the case of pistons, the outside diameter is larger (oversized) when the block is bored.

Now, by that same token, if the connecting rod bore or main bearing bore were to be enlarged, the bearings (based on this naming convention) would be oversized.