You are allowed 2*7 Kgs in J, which is close to 30lbs. I have never seen them actually check the weight and I suspect many passengers may have a few Kgs more. A single 30lbs carry on may be pushing it a bit though. That’s not a carry on, that’s a smallish suitcase! (My own checked luggage often weighs less than that. I hate lugging heavy items around airports (especially DXB) and the priority luggage delivery service works very well with EK in my experience.)