Genesis S-330 Burner bolt thread

Sorry for having to ask this as my first post but I've been searching a few days for this answer without success.
I have a Genesis S-330 with 4 burner (3 main plus 1 sear). I was able to use vice grips to remove the 4 bolts holding the burners down. I want to replace them with heavier duty hex bolts rather than the OEM ones.
Does anyone know the thread size for these bolts?
I did bring the old ones to local hardware store and the bolt did fit (loosely) into 1/4 x 20 nut. But when i brought home that size bolt, it is too big and did not fit.
Thank you.

Chin,
Welcome to the forum.

Too late now, but it's recommended that you leave those bolts in place when replacing the burners. They aren't meant to be tightened down, but stick up a little so the burners can slide under them.

I'm not sure what size they are, but there's no reason not to put the original screws back in. If they won't go back in, you might have to tap out the holes for your preferred screw.

Lots of good rehab tips in the stickies at the top of the gas grill forum.

Yep, if you are talking about the bolts at the ends of the burners, they are not meant to be removed. I am not sure what size they are on the newer grills but I would just either put in the old ones or maybe buy stainless steel ones to replace them. If you messed up the threads from the original bolts, you can probably just find a slightly larger one to put in place of it but you may have to drill out the holes enough to accommodate them. If you try to jam to big of a screw/bolt in there, you might crack the cook box.

I think on the 330/any of the NS grills they have to come out (not 100% sure since I don't own one and never will) but I think Weber designed them to be taken out to remove the burners

Weber's instructions for replacing burners do call for those to be removed when replacing the burners, but the burners can easily be replaced by loosening the manifold (don't have to remove it) and leaving those bolts in.