Shoud I relieve my block

[Bored&Stroked]

The question comes back to the application and usage of the engine. In a performance built engine, a relief will help - especially if you have good port/valve work done, cam, heads, etc.. In a stocker type engine, it will reduce compression and there is not a huge amount of benefit. Also, what RPM do stock engines usually run at?

Pete, Ron and I probably relieve every engine we build - as we do not build stock type engines. I've not built a stock engine in 40 years.

If I was building a stocker or mild performance type engine, I'd probably do more of a blend of the transfer areas around the valves - more of a 1/2 relief to improve flow out of the valve pocket. Also, consider that stock type engines are already suffering from low compression - do you want it any lower?

Here are a few pictures of what I'll call a 1/2 relief - it was done for a 276 cubic inch street engine running dual carbs and a Potvin 3/8 cam. Stock valves sizes, street porting and guide work (on the tops). This is kind of a "tweener" - improved ports, a 1/2 relief - not a competition style engine, but surely an improvement over stock. It ran extremely well in a street driven Model A roadster:

PortsFinished1 copy.jpg

ReliefWithRadiusBoreEdge copy.jpg

GuideInPort1.jpg