Small end bush

[Don Madden]

And be very careful to hold the reamer centered on the bush. Cheap ones tend to grab & bite too much & even a good one may if the reamer is too much larger than the bore.

Cheers, Don.

[Biscuit]

Following on from Don, try to get hold of an old piston to hold the reamer square, less chance of it grabbing or ging skew-wiff (whiff?)