as kidd said take out all 4 plugs and turn motor over a few times or blow out with an air compressor and a straw. also not every engine slings a rod... i got a free b20 bcause it hydroed but the rod just bent slightly and kept tapping the sides of the bottom of the bore. we didnt know 4 sure till we took of the head and the #1 liked a 1/4 of an inch comming to the top.