Odoo limits meta Title to 70 characters, but Google doesn't have such limit. The two real limits are :
Below each title in its search results, Google prints nearly 160 characters. It is often a sentence from the Description field. But if there is no search related sentence in your Description, Google will pick words from the page content. Help Google! write longer descriptions, more sentences, more words. Google will choose one sentence from the available ones. This module allows 320 characters in meta Description. Note that meta Description is not related to SEO, but to Search Engines Result Page (SERP). Google will not use it for referencing your page but to print its search results.
Additionaly, this module will display preview with Google's colors and truncates URLs and title according to Google's rules.