C#: How to I extend the timeout of a WebClient call? (30 seconds is just not long enough)

My Azure function is calling web services that take longer than 30 seconds to complete, so I needed to extend the default timeout the WebClient class.

I created the following base class:

using System;
using System.Net;

namespace MyHelpers
{
    public class MyWebClient : WebClient
    {
        public int Timeout { get; set; }

        public WebDownload() : this(180000) { }

        public WebDownload(int timeout)
        {
            this.Timeout = timeout;
        }

        protected override WebRequest GetWebRequest(Uri address)
        {
            var request = base.GetWebRequest(address);
            if (request != null)
            {
                request.Timeout = this.Timeout;
            }
            return request;
        }
    }
}

I set the default to 3 minutes. I can then use it like I would a usual WebClient call:

private string ExecuteAPI(string url, Dictionary<string, string> parameters)
{
    try
    {
        using (var client = new MyWebClient())
        {
            foreach (var param in parameters)
            {
                client.Headers.Add(param.Key, param.Value);
            }

            return client.DownloadString(url);
        }
    }
    catch
    {
        return string.Empty;
    }
}