New Block Maximum value: 254

I created a new block but the max value is 254. Is there a file I can edit to make the systems max value over 254 and make it 10000 ?

Sample is here http://tankspace.com/search_home.php and I want the tank size to be much higher for the search.

Anyone know how to increase this?

It will be hard to select precise value if range is too long.

For long values - I would recommend to use regular input.