SpudFiles

I am in the process of making a semi-advanced combustion and just was wondering how necessary it is to be able to vent the chamber via a ball valve with a fan. I was planning to follow something like design on Pete Zaria's "Complete Plans" but I cannot find one of the large plastic ball valves that seem to be used cheaply. However I do have a brass 1/4" ball valve which I could thread into the end, this one here:
http://www.topmaq.co.nz/product_detail.aspx?id=AIAC6050
It seems to have quite a small ID though so would this provide enough airflow or is it not worth the effort?
Any answers or alternative suggestions are greatly appreciated. Cheers.

You need to properly vent the chamber to allow fresh, unused oxygen in for the reaction to work well.
I don't think 1/4" would be enough. You could always build a 'Quick Vent' System that's been used a few times, and especially on Gort's combustions.