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Henry Floored · 08-07-2010, 06:29 PM

A few more thoughts on the intake porting and their ability to feed the larger displacements in the Flathead Ford. Certainly it would be nice to have the option of bolting on larger ports like our OHV bretheren can easily do. Unfortunately that's not an option for us. Ron gave us an excellent vertical cross section of a Flathead intake port. The area that appears to be "pinched" is actually the ramp that directs the intake charge into the combustion chamber. With the water passages above and below it looks like quite a bottle neck. In my opinion though it's not as bad as it looks. When I port the intakes most of the material I remove is from the sidewalls of the intake ports. I like the design of the intake port and I don't think I can improve on the Ford engineer's ramp effect. If you think about it ohv engines like the sbc have ramps in them to direct flow as the port snakes around the pushrods. I think the best way to approach Flathead intake flow is to optimize flow through the port just like you would on an ohv engine. Forget about making the turn down the cyl for awhile. After finding the practical limits of what the intake port can actually flow I'd build an area over the piston that could accept about 125% of that number. I'm talking a healthy cyl head relief. This is the approach I'd like to try on my next engine. Step one is getting a block section with the intake ports and getting the fixture built. Might even be able to talk the local race engine builder into flowing it on his Superflow bench.

08-07-2010, 06:29 PM	#108
Henry Floored Senior Member Join Date: May 2010 Location: Florida Posts: 583	Re: Boring a flathead A few more thoughts on the intake porting and their ability to feed the larger displacements in the Flathead Ford. Certainly it would be nice to have the option of bolting on larger ports like our OHV bretheren can easily do. Unfortunately that's not an option for us. Ron gave us an excellent vertical cross section of a Flathead intake port. The area that appears to be "pinched" is actually the ramp that directs the intake charge into the combustion chamber. With the water passages above and below it looks like quite a bottle neck. In my opinion though it's not as bad as it looks. When I port the intakes most of the material I remove is from the sidewalls of the intake ports. I like the design of the intake port and I don't think I can improve on the Ford engineer's ramp effect. If you think about it ohv engines like the sbc have ramps in them to direct flow as the port snakes around the pushrods. I think the best way to approach Flathead intake flow is to optimize flow through the port just like you would on an ohv engine. Forget about making the turn down the cyl for awhile. After finding the practical limits of what the intake port can actually flow I'd build an area over the piston that could accept about 125% of that number. I'm talking a healthy cyl head relief. This is the approach I'd like to try on my next engine. Step one is getting a block section with the intake ports and getting the fixture built. Might even be able to talk the local race engine builder into flowing it on his Superflow bench.