Engine rebuild questions

I got a rebuild kit from evergreen parts and acessories, and the main bearings both have grooves and oil holes in the upper and lower bearings. Is it supposed to be like that?

That is fine. It is a way to idiot proof the bearings so you can't block the oil port with the wrong bearing half.

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Engine is put back together and running and driving. I let It idle for a little bit on initial startup let it get up to temp, shut it off and waited for it to cool down. Then I changed the oil and re-torqued the head. First time driving it around, Its sort of stumbling or breaking up when I get closer to 2.7k rpm. Im not racing it, But doing the correct procedure for breaking the rings in. I have the Weber 38/38 and currently I have it 1 1/2 turns out.

EDIT: I havent had the chance to get my hands on a timing gun just yet so timing is just by ear