what is wrong

[no1chevyboy]

im trying to check my belt deflection but every time i push down on the belt it shoots my straight edge through the hood i have three holes already wtf am i doing wrong

 

[Bischof]

Obviously you're using it backwards.
LMAO

 

[Dave M]

Idle the engine down.

 

[maxdlx]

Don't check iwith the motor running.