I am creating a fuel block, and I want it to be unstackable in the furnace as well as be turned into another item when used as fuel, similarly like lava buckets turn into normal buckets when used as fuel.
Problem I am facing is I can't find how to override the item property or the vanilla furnace behaviour.
Any help?

I think what you need is to add these two properties to Item.Properties when you register your item.

• .craftRemainder(Item you want it to become)
• .stacksTo(1) 

This is how the lava bucket does it:
 

new Item.Properties()).craftRemainder(BUCKET).stacksTo(1).tab(CreativeModeTab.TAB_MISC)

The only downside is that you probably won't be able to use the fuel block in recipes because it will give the item it will turn into as a remainder.

16 minutes ago, h3tR said:

I think what you need is to add these two properties to Item.Properties when you register your item.

• .craftRemainder(Item you want it to become)
• .stacksTo(1) 

This is how the lava bucket does it:
 

new Item.Properties()).craftRemainder(BUCKET).stacksTo(1).tab(CreativeModeTab.TAB_MISC)

The only downside is that you probably won't be able to use the fuel block in recipes because it will give the item it will turn into as a remainder.

Thanks, the .craftRemainder(...) worked, but with the stacking I still would like it to stack up to 64, but only stack up to 1 in the furnace if possibl and I dont know how to approach it.

 you might be able to do that with mixins. I’m not sure how they work but I suggest looking into that

1 hour ago, Oksas said:

Thanks, the .craftRemainder(...) worked, but with the stacking I still would like it to stack up to 64, but only stack up to 1 in the furnace if possibl and I dont know how to approach it.