So here is the problem I created a custom (lamp post block) using obj model because for some reason in the program block bench you cant do blocks higher than 32(i think that is json file limit??).

but i have the bounding box set to 4 blocks tall and it works for bounding box but the collision is only 2 blocks call and if i am not looking at the bottom(what would be one block) the bounding box doesn't show how can i fix this.

 

Thanks Discult.

 

Block Code:

 

Lamp post  block:

https://pastebin.com/rYvsddCS

 

Block OBJ: 

https://pastebin.com/CshfdFyz

 

 

Image 1:

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Image 2:

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There is a reason models are limited to 2 blocks tall max and you shouldn't even do that. Models should be a 1x1x1 cube. If you need a big model either use a TESR or multiple blocks each with different parts of the bigger model. The collision boxes won't work properly if they are greater than 1x1.5x1 and even the 1.5x on the y axis is a hack in vanilla. 
Solution - use multiple blocks for big collision boxes.

Okay noted thank you for the reply