pistons

schillaz

Does anyone know if this is a hudson piston? I've never seen one like this. Interesting!

Geoff

I've never seen one like that either. I certainly cannot see any advantage of such a design.  

Hans

perhaps some one had 2 cycle outboard motor experience.

Various types of shapes have been used to deflect combustible mixtures as well as increasing compression.

Someone may have realized the shape of the cyl head space could be used to do both, raise compression and improve flow turbulence for better combustion.

An interesting concept to think about.

I personally have milled Essex cyl heads .127 and more. 
 At .127 the clearance for passage from valve pocket to piston (including gasket) was very tight. However the compression was increased substantially, estimate from 5.7 to aprox 8.3 cr.

We should recall the Essex engines used Ricardo  shaped cyl head cavities to gain better volumetric flow so a higher cr and improved combustion could be utilized/ obtained.

Hans

With the large valve pocket on Essex heads I think the possible use of "padding" as used on engines to increase cr ratio is a possibility, keeping in mind  cyl head hot spots vs cooling.

Clerances vary from valve faces to head/gasket face is significent, for each Intake and 
Exhaust valve.

There certaily could be room for improvement..........

schillaz

That's what I was thinking. Someone cast their own pistons back in the day, but figured I should ask incase someone has seen them before. Trying to get the engine casting numbers now for some more info on the block. Will update when I have the info.

bob ward

Interesting. Possibly the thought was to improve combustion by directing 2 jets of combusting gases, one each side of the lump, into the space above the piston.

terraplane8

Strange as the lump would appear to shield the combustion chamber from the spark plug which I assume is placed over the valves.

dave11

My guess is this may have been an experiment to raise the compression with out drastically modifying the cylinder head?

It would be interesting know how it performed

schillaz

casting on the block below the distributor is:

  0134
310111

So I believe it to be a 54 308 block. It doesn't look like 2 in valves to me. (cant get a measurement yet)

Ric West IN

Yes, 310111 is a 1954  308 block.  Which foundry?  CWC, WF, or  ?
Could the 0 in the date code be a D ?  CWC used a letter for the month, A = January B is Feb. 

schillaz

Its CWC so must be a D.  thanks

superwasp

Schillaz, are you going to try to use them? I think we're all really curious how they'd perform.
I've seen performance flathead Ford pistons with a depression in that same area, but being a depression rather than a dome, that's obviously the inverse concept.