273 / 318 Exhaust Manifold Question

cudamark said
To answer your original question....yes. I've gasket matched my 273/4 engine and cleaned up slag and other casting flaws so that the gases flow a bit freer. I slicked up any rough casting where I could reach with a long shanked grinding stone. Beyond that, I would have to extrude hone them for the ultimate in flow. I couldn't justify that cost for street use. I also did other engine mods, so, trying to compare a performance increase for just the exhaust changes would be too hard to determine.

Now extrude hone. That's a cool process. For squeezing every lst oz. of power out of those factory manifolds. The small block drivers manifold restriction around the steering shaft is like they say "like pooping through a straw" No way around it except for electric steering and may be a B or C body manifold.

extrude hone process.jpg