I currently have a 20r motor and was contemplating taking my 20r head and putting it on a 22r block, however, since the 20r and the 22r blocks are essentially the same I was wanting to go a head machine the 20r block and have it bored out to 22r piston size. I know it's better to use the aluminium rocker arms out of a 22r head instead of the steel 20r ones but what other mods and/or advice can anyone give me? Has anyone bored our a 20r motor to 22r piston size?

 

the walls between each piston would be too thin, im not sure on the specs but the 22r is bigger then the 20r so therefore if you bore the 20r out too 22r size all youd be doing is making the material between each cylinder weak, and for the price you can find a 22r block it wouldnt be worth just honein a good 22r block, youd be in it for more money