How long should it take to break in molly rings?

 

Has nobody used molly rings?

 

sure lot of people use moly rings, and some have even used the plsma moly rings, i know of a few adverous types who use chrome rings and i've used lot of cheap cast iron rings in the little B&S kart engines i use to run

 

So, how long should it take to break in moly rings?

 

from what i hear and have seen very fast. someone once told me moly rings seat almost as soon as the engine first fires. they do require a fine finish on the bores

 

Thanks ede. The reason I ask is, I just rebuilt my engine and only have about 11 miles on it, (I know it's not much yet), and I'm getting a little bit of blow-by. Should I be worried yet?

 

Are they barrel-faced?

 

Ummm....I don't mean to sound like a complete idiot, but what does barrel-faced mean?

 

Barrel-faced refers to the surface of the ring that rides on the cylinder wall. It will have a barrel face to out - as in a rounded edge that resembles a barrel when viewing the cross-sectional view of the ring - so that the ring itself breaks in faster since there is less wear that needs to take place before the break in is complete. From what I have heard, the break in is nearly instantaneous with this type of ring.

 

I hate to contridict what you have said but my machinist says that molly rings take twice as long as regular rings to break in. Thats why they require a finer finish on the bores so that they don't have as much ruff surface to cut through., He does not recomend them on motors that aren't going to be ran hard because they can never really seat. The reason for this is the extra lubricating qualities of the moly. I pulled my motor apart after 10,000 miles ( wiped cam lobe) and the cylinders still had the cross hatching on them. I trust him since he has built motors for 30 years and builds most of the circle track motors in the area.

 

I am referring to barrel-faced rings - not necessarily moly.

 

Ohh ok that would make sense. But have you heard the same things about molly? This is what i have been told and I have never really heard a discusion on the topic. Any of the guru's have anything to add?

 

Well I'm no machinist and I only know what my machinist friends tell me (or more accurately, what I understand that they tell me...lol)... But from what I understand, you are correct about the moly rings being more difficult to break in due to the surface of the ring being so fine and hard. But the moly and plasma moly rings have higher tension rates and are stronger as well which makes them handle higher cylinder pressures (more power) better and makes them last longer...... But don't take my word for it..... Where are the gurus???? So from what I know and somewhat experienced, if you go with a plasma-moly ring that is barrel-faced, you get the best of both worlds since they break in fast and are a very strong ring.... Now I know somebody has to have a better explanation of this!!! My head is full of hypothesis testing and two-sample proportion confidence intervals (big test 'morrow)......