340 break in question

krazykuda said

I'm not saying that there is no break in for roller cams and lifters...

I'm saying it's a good idea to keep your engine RPM's low as possible until it's warmed up...

Here's a graph of engine wear vs operating temperature... This is for cylinder walls, but applies to any pieces that are moving in relation to each other without direct oil pressure on them...

View attachment 1715669227

Click to expand...

I’ve seen that before. Not sure what year it’s from. I do know that cooler coolant temps do not increase cylinder wear. Cold, thick oil does.

If you can get the coolant down to 160 (or lower) and use a good oil and get it 180 or hotter it will make more power and not wear out the cylinders.

EDIT: bore geometry has as much impact on cylinder wear as anything else. If the bores aren’t finished correctly it won’t matter what the coolant temp is or what oil you use. It will wear out and not seal.

The harder the ring, the deeper the valleys need to be to retain oil. The oil is what seals the ring to the cylinder. The softer the ring, or the more porous the ring face, the more shallow the valleys can be.

The included angle of the crosshatch makes a big difference in oil control, cylinder wear, ring rotation speed and oil consumption.

It’s not just a one finish fits all deal and it hasn’t been that way since the early 1990’s.