honing cylinders

what grit is recommended for ring break in? I am sure there are many answers. I am using emgo pistons with cast iron rings most of the time

On a Sunnen bench hone it would be a J95. The 9 means 500 grit and 5 is hardness. I'm not familiar with their automotive hone where the block stays still and hone moves but probably the same. I use a brush hone also, I think the surface comes cleaner and smoother.

Over 40 years ago, our Polytech tutors were advising not to de-glaze bores when fitting new rings to old bores. . Apart from removing material from the bore to reduce the life of the bore, it has been proved not necessary so long as the engine is driven correctly after the ring job. Some years ago, after I blew the rings out of my pistons, I fitted new Emgo pistons etc, rebuilt the engine without de-glazing [ note honing is for removing metal to reshape and object ] the bores. I rode it pretty firmly for the first 20 odd miles and its still running fine.

Note, our best circuit for running engines in was a hill nearby with a lot of tight corners where you needed to back off, then add power. Load and unload the engine is the best way to run it in. Don' t nurse the bloody thing. Engine re-builders, don give it to your customer to run it in, do it yourself.

Dereck

The best customers to run engines in were those with more money than sense, who got in their car and thrashed the shit out of them.

In general, the guidance by piston ring makers (Hastings, etc) is that if the original cylinder crosshatch is visible, no honing is necessary; if it's not visible, honing to establish a crosshatch IS necessary. Hand drill-operated brush hones are typically used in the home garage for this purpose though most reputable builders don't like them due to the imprecise nature of the manual operation. In any case, the rings should come with instructions re honing requirements. In the absence of any strong personal preference/experience, just follow whatever they are

As far as installation of the pistons in the bores, there are many opinions re rings/cyl wall installation. A popular current method in engine building is "dry" installation - no lube on the rings/cyl walls when installing the pistons. Some dry method users employ a "wipe" of a rag with WD-40 or something similar on the walls to prevent rust after honing but no oil or other typical lube. The opposite method is, of course, the old, "Lube the cyl walls with 30 wt (non-synthetic) and dip the piston/rings in a pot of 30 wt oil and install." You can't get much more opposite than those two! There are, of course, many folks who use something in between those two methods! Frankly, both extremes and everything in between seems to work...

For break in - a common engine-builder method is to perform 10 dyno runs, each with succeedingly higher rpm/load up to max. At the end of those 10 runs, the engine is ready for normal use, whatever that is (competition/street/whatever). No further break-in is required. You can do the same on the road, preferably, as Kerinorton suggested, up a hill.

I think a good part of my problem is that I live in the city and it's hard to give it a good break in. I use the dry method...keep the rings free from oil, dry cylinders and a very slight smear of #10 non-detergent hydraulic jack oil on the piston skirts.

Yes, and I should have mentioned, the "dry method" only refers to the rings/walls. Normal lube of piston skirts and all other associated parts is still done. I worked in performance/competition engine building and over the years we gradually used less and less piston ring/wall lube until by the time I quit doing it professionally, it was all "dry."

BUT, to be fair, there are plenty of builders who do not like that method!

some major race engine builders do a final finish with a brush hone.

MexicoMike said:

In general, the guidance by piston ring makers (Hastings, etc) is that if the original cylinder crosshatch is visible, no honing is necessary; if it's not visible, honing to establish a crosshatch IS necessary. Hand drill-operated brush hones are typically used in the home garage for this purpose though most reputable builders don't like them due to the imprecise nature of the manual operation.

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"some major race engine builders do a final finish with a brush hone."

That's interesting. I'm surprised that any high performance/competition engine builder would hone a cylinder to final finish with a brush/electric drill. My gut reaction is that it sounds like a heart surgeon using a swiss army knife! OTOH I quit doing that stuff professionally 10-12 years ago so it sounds like my thoughts and experience are out of date. Oh well, that's the way of the world; things change...

MexicoMike said:

"some major race engine builders do a final finish with a brush hone."

That's interesting. I'm surprised that any high performance/competition engine builder would hone a cylinder to final finish with a brush/electric drill. My gut reaction is that it sounds like a heart surgeon using a swiss army knife! OTOH I quit doing that stuff professionally 10-12 years ago so it sounds like my thoughts and experience are out of date. Oh well, that's the way of the world; things change...

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Brush hones have been around donkeys years, even I've used them.

Woe unto he that does not keep one moving too. I've always liked them.

Mike here is some reading on it

I use coarse sandpaper and work at an angle in the bore from both ends. Good wash afterwards.

Steves said:

I use coarse sandpaper and work at an angle in the bore from both ends. Good wash afterwards.

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Didn't this method go out with the ark?!