21 Stud cylinder head with unique combustion chamber.

[AzBob]

In my search to replace corroded aluminum cylinder heads, I came across a pair of these. Head is dated 5-12-48 with part number 40-6050-B. (Cast Iron.)

The last photo is of my existing aluminum (40-6049-A) which shows a different chamber shape.

40-6050-B appears to be a unique combustion chamber shape. Any ideas on the purpose of this shape or why it is different?

 

[petehoovie]

In my search to replace corroded aluminum cylinder heads, I came across a pair of these. Head is dated 5-12-48 with part number 40-6050-B. (Cast Iron.)

The last photo is of my existing aluminum (40-6049-A) which shows a different chamber shape.

40-6050-B appears to be a unique combustion chamber shape. Any ideas on the purpose of this shape or why it is different?

 

[AzBob]

Thanks petehoovie for the enlargements.

 

[Brian]

They are aftermarket, the name of the manufacturer eludes me for now. They also used the same configuration for dome top pistons; simply domed tthe heads. That is why the combustion chamber is shaped like that; to lead into the dome...same castings. I run these same [flattop] heads on my current engine

 

[FlatheadTed]

I am going to run this type on my current build .with flat tops .

 

[Brian]

the reason I'm running them is because when I was looking for cast iron heads, every left hand factory head I located was cracked!! RH heads were all crack free...dunno why. I located set of NORS heads in Australia, so am running them.

 

[AzBob]

They are aftermarket, the name of the manufacturer eludes me for now. They also used the same configuration for dome top pistons; simply domed tthe heads. That is why the combustion chamber is shaped like that; to lead into the dome...same castings. I run these same [flattop] heads on my current engine

Thanks Brian, makes sense now. I can see how the unusual combustion chamber shape is for transitioning to the machined dome recess on the domed head piston versions.

Any ideas on compression ratio? How do they perform?

 

[Brian]

How do they perform?


In my application, they are all right. However, my application is a 255 cu in 21 stud...when I had Eddie Meyer heads on it, it had too much compression; detonated to hell! I fitted these to overcome that on account of their lower compression. I am unable to advise how they run on a stock displacement engine, sorry!

 

[AzBob]

Thank you Brian and FlatheadTed for your replies. Apparently information is scarce on the differing 21 stud combustion chamber shapes.

Comments with regard to replacing aluminum heads with cast iron welcome. Obviously they are heavier. Disadvantages, advantages?

 

[The Art Doctor]

I believe I read that after a very short period of time Ford did not provide replacement aluminum heads only cast iron for the 40- heads. The story I was told was that even when fairly new the aluminum heads were a bear to get off as the steel studs corroded to the aluminum heads and many were removed with a chisel. There were reproduction 40- aluminum heads made a long time ago, I believe that is what is on my '34 5 window. H&H does have 21 stud finned aluminum "Sharp" heads for $1600 a pair https://handhflatheads.com/product/sharp-21-studs-heads-1932-36/ Aluminum heads allow about 1 extra point of compression ratio with the same octane gas over cast iron without detonation. That is the only performance increase if all other things are equal. The weight and quicker thermal heat loss (and aesthetics if that matters to you) are the only other benefits I can think of. You can always grind the cast iron smooth and paint them with aluminum paint to make them look more authentic if that is a consideration.

 

[AzBob]

I believe I read that after a very short period of time Ford did not provide replacement aluminum heads only cast iron for the 40- heads. The story I was told was that even when fairly new the aluminum heads were a bear to get off as the steel studs corroded to the aluminum heads and many were removed with a chisel. There were reproduction 40- aluminum heads made a long time ago, I believe that is what is on my '34 5 window. H&H does have 21 stud finned aluminum "Sharp" heads for $1600 a pair https://handhflatheads.com/product/sharp-21-studs-heads-1932-36/ Aluminum heads allow about 1 extra point of compression ratio with the same octane gas over cast iron without detonation. That is the only performance increase if all other things are equal. The weight and quicker thermal heat loss (and aesthetics if that matters to you) are the only other benefits I can think of. You can always grind the cast iron smooth and paint them with aluminum paint to make them look more authentic if that is a consideration.

Art Doctor, thanks for the Ford V8 cylinder head history. I looked at the H&H Sharp heads. $1600 is a pretty expensive alternative. Not exactly apples to apples but one can buy a new high compression Model T aluminum head for $475.

My thoughts on using the cast iron heads are the same as you described. Would grind them smooth and paint with aluminum paint. The thing that attracts me to these particular iron heads is they are new NOS aftermarket.