"Conventional" thinking says put it over the exhaust valve but think about the space you need to have over that valve in the combustion chamber? Really wanna lose all that compression? Your head design will have alot more to do with location. You will not see a big reduction in timing in any...
As stated earlier relieving the block is "old school tech" on flatheads for pulling tractors. Spend some time on a flowbench and dyno and you will soon find that out, yea it looks cool and sounds neat to tell people about doing it.
The flatheads they build for pullers are nothing like the old...
Everything u ever wanted to know about building your own flowbench is located on my forum located here:
http://www.tractorsport.com/cgi-bin/forum/cgi-bin/ikonboard.cgi
Happy surfin'
