1960's Lawn Ranger Belt Tension Issue

[Jersilb 10]

Hey guys, I'm new to the forum (very thankful to have found it) and a fairly new Wheel Horse owner. I believe my tractor is an early 1960's E32 Lawn Ranger. I haven't been able to pin point the age or exact model yet. Here is the problem I am currently having. My barn find did not have an engine so I used a predator 212cc as a replacement. I have found a pretty good pulley for the engine, but seem to be having trouble finding the best length to utilize the clutch/brake function. I have moved the engine back a bit to allow clearance for the hood. I have two 1/2" v-belts that I am trying to work with, one is a 61" and the other is a 62".

I have also read and recently learned that the belt cover must be on to make sure the belt doesn't spin off. However, I can't seem to get the rear transmission pulley to stop spinning when I engage the clutch pedal. The belt definitely seems loose enough when using the 62" since it will literally fall off when I engage the pedal all the way. It even seems a bit loose when only pressing half way down. Anyway, I have posted a few pics to show what I am talking about. Any help on proper belt tension would be greatly appreciated. Glad to be here! 

[slammer302 2,155]

you will need the belt guard it helps support the bottom of the belt when the clutch is pushed it gets slack around the pulley  

And the belt ur using looks a bit small

[953 nut 55,091]

     There is also a part missing in the idled that will grab the belt when you push down on the clutch.

Should be located near the top.

[Jersilb 10]

Thanks for the help and pics Slammer302 & 953nut! I was able to use the 62" belt and modify the belt- guard to make it all fit together. Worked out pretty well. I have one happy young man! Thanks again for the help!