stumbled across this flathead info

[Johnny 5]

I've never been a huge fan of relieving but this illustration shows how contouring the block should aid flow. I think I'll try it on my VL and dyno the results:

http://www.midstateantiquestockcarclub.com/flat_heads2.html

Has anyone tried this combustion chamber mod? It supports Earl Edgerton's flow theories and doesn't look like it would be difficult for the home porter:

http://www.midstateantiquestockcarclub.com/flat_heads2.html

I know this is Ferd stuff but the concept should work on any modern 'closed chamber' flathead.

[Don Coatney]

Johnny 5;

The link you posted is for a furd V-8 flathead. Not sure if that

technology will work on a Mopar flathead 6. Pictured below is

a picture of a relieved Mopar flathead engine block. I shot this

picture on my last visit to George Asche. I do not have any

additional information on this engine.

[Johnny 5]

That's pretty much what was outlined on the website. It follows the contour of the slope leading down from the combustion chamber to the cylinder rather than restricting it.

[Don Coatney]

Problem I see with this is a big reduction in compression ratio. It appears that any gain from improved flow would be lost in reduced combustion chamber pressure.

[Johnny 5]

I'd have to check. Doesn't look like more than a quarter point total would be lost. It would make up for additional restriction caused by milling the head which is where most folks get their compression from anyway. Sounds like a new project.......

[Tony WestOZ]

I am sure I read in an articale a couple of years ago were this was a good modification on Ford and Hudson flatheads but not much use on Chrysler products.

Had something to do with the valves on the Chryslers don`t sit in pockets (or lower in the block) than the others do.

[Johnny 5]

I didn't know that the valves were countersunk in other engines. The one Don showed in the picture is probably no good anyway. It's heavily pitted and whoever machined the reliefs went too far and cut into the valve seats. Shaving the block might correct this mistake. If I were to do this I'd stop about .150" away from the valve seat edge and radius the step. That would reduce the overall volume of the relief and should aid flow. Blueprinting is critical. A clay (or clear silicone) mold of the combustion chamber overlaid on the block would verify if this is worthwhile or not.

[Don Coatney]

Actually Hudson valves are set at an angle that lends itself to better flow right from the factory.

[Johnny 5]

They're 12 port blocks too, right?

[Don Coatney]

12 port is correct.

[Bodacious]

I am sure I read in an articale a couple of years ago were this was a good modification on Ford and Hudson flatheads but not much use on Chrysler products.

Had something to do with the valves on the Chryslers don`t sit in pockets (or lower in the block) than the others do.

I've read this too but am keeping an open mind. This is my first modified build of a flathead and of a Mopar flat six in particular. As usual with a build for a street car that will be driven a lot, power as well as flow, combustion efficiency and thus overall efficiency will be important goals.