Hi all first things first i do not spell good now iv got a problem with sr 1  the engine had a bag knock on it when i removed the hed the piston was and stil is hitting the hed  iv re shimmed the hed so the clerins is .37 with the led a cros guginpin  but the piston is still hiting the when   running  this i no as removed the hed a gain now iv got a nuw hed set and iv put all shims in plus 3 more 003 shims but the same thing piston still hiting the hed when running the piston is very prowed of the cyilinger wher the piston is hiting is from the conbustion chamber on the piston on the push rod side and in between the valvs on the opesit side am am well over on the shims taking the clerence to .45 a cros guginpin  but the valvs do not tuch piston do you think piston is not sqer or a con rod problem iv also chaing the big end  can you give avice on this this engin has got my beet