flex hone

The bores on the 73 850 engine I am building measure within spec but are fairly smooth. I'm going back with the original pistons and new Hastings cast iron rings. I am trying to decide whether to use a flexhone to break the glaze. They come in different grits. Seems like either the 240 or 180 would be appropriate for the cast iron rings. Any one used this before. There's only one machinist I would trust around here to do a hone and he has a big backlog and is a hassle to get to. Sure would be easier to do it at home.

Should work good enough to get new crosshatch.

Given that choice, I’d vote for 180 for iron rings, or maybe even 150 if you want them to bed in quickly. Triumph used 150 at the factory, but I don’t know what Norton used. My experience is 220 or 240 is just too fine for iron rings, and 180 works much better. Just used 180 on my BSA Spitfire, and 220 on a T140D with modern steel rings in it, both seated quickly. I have had the experience of iron rings going on for a long time without seating using a 220 or 240 Flexhone and you want to spare yourself that.