starter knock
 

i have a 400 sbc and ive been threw a starter or two and a flywheel and when i go to start the motor it will spin over and the the starter starts knocking and usually get stuck and doesn't turn over give it a little bit and i can turn it over again it will turn it over and get it started but once i turn it off and try again it will struggle and knock

and the starter is planty strong enough and so is the battery anyone every had this happen

make sure you got it shimed may or may not be the problem just a sugestion that comes to mind and make sure the teeth on the fly wheel are matched up with the one on the bendix gear

starter
 

What kind of starter are you using? Try checking your bolt hole size going through the starter mount. I had a set of bolts one time that fit the threads in the block. It turned out the starter was for use with metric bolts and allow just little play to cause lots. of problems

Amen.

Small amount of tolerance off ='s bigger problems... does not take much.