New block

[Tod]

Originally Posted by Ol' Ron

I like the idea of keeping the valve/lifter area stock. Some modes to the water jacket in this area will help those that want to search for more power happy. As for the center exhaust port, it's the best flowing port in the engine. Just use a flow bench. The fact that it is used for two cylinders has no affect on flow, as the cylinders don't fire at the same time. In fact, The firing order of the Flatheads fireing order is such that all the end cylinders fire in succession first. Then the center 4 cylinders fire in sequence one side at a time. Now with the proper exhaust manifold you can use this to evacuate the end cylinders. Plus you don't need to make any mods to the block. So leave the center exhaust port alone. Pretty soon we'll get nothing.

I was thinking about using the dipped design of the center exhaust port on the 2 ends as well. I'm going to try to keep the exhaust ports close to original right under the valve, but try to smooth out the flow some and get rid of as many sharp angles as possible. I just don't see the sharp corners helping exhaust flow. Since the area of the port diameter where the exhaust manifold bolts on is about 1.5 square inches, if I can keep the port no less than that all the way through, it should do nothing but help flow. More "direct" and less turning.

Tod

[Ronnieroadster]

Originally Posted by Tod

I was thinking about using the dipped design of the center exhaust port on the 2 ends as well. I'm going to try to keep the exhaust ports close to original right under the valve, but try to smooth out the flow some and get rid of as many sharp angles as possible. I just don't see the sharp corners helping exhaust flow. Since the area of the port diameter where the exhaust manifold bolts on is about 1.5 square inches, if I can keep the port no less than that all the way through, it should do nothing but help flow. More "direct" and less turning.

Tod

Tod your idea on the exhaust port flow is exactly how the French flathead blocks were cast. The French block has a number of design improvements similar to what you and others have mentioned. Maybe someone could loan you one of those blocks so you could see these improvements first hand.
Ron