Has anyone else come across "B" cast heads with small valves?

[Engineresto]

A while back i purchased a VH ss with a 4.2. Unfortunately the previous owner wanted to keep the bottom end so I removed the engine and pulled the heads off.
To my surprise the heads had the "B" scratched into the mould before casting.
I thought this was quite strange as I have never seen a 4.2 with b casts before. Even more surprisingly they have std 4.2 sized valves in them. If you remove the valves there is a big step under the valve in the bowl area which was never cut for larger valves.
Just interested to see if anyone has seen this before or if they have any theories why this happened?

 

[Smitty]

you sure there is a B scratched in ? and ... not a wavy sand casting join dag
that was not fettled during manufacture?

proper B Casts with large valves have these ..

 

[Engineresto]

you sure there is a B scratched in ? and ... not a wavy sand casting join dag
that was not fettled during manufacture?

proper B Casts with large valves have these ..

 

[Engineresto]

Yep that's what it looks like. I have 3 other sets of B casts and all with markings very similar but none have small valves( 1.77" inlets and 1.47 exhast from memory).
I am an engine re-conditioner by trade and have been collecting stuff for years but have never been able to find an answer to how these came to be. The b casts must have been cast with different ports because normal 253 blue heads when fitted with this size valves don't end up with a horrible step in the port under the valve. Basically the port design for a b cast must be for larger valves, when the seats where cut for the smaller valves it has left a big step. with a std blue heads this is not the case. I will attach some photos when I get a chance.
Wondering if holden ran short on std blue castings and used a few b cast on 4.2's at some stage.

 

[Smitty]

... just a thought what is the casting part number on the heads?
Between the bolt bosses..

 

[shane_3800]

Yep that's what it looks like. I have 3 other sets of B casts and all with markings very similar but none have small valves( 1.77" inlets and 1.47 exhast from memory).
I am an engine re-conditioner by trade and have been collecting stuff for years but have never been able to find an answer to how these came to be. The b casts must have been cast with different ports because normal 253 blue heads when fitted with this size valves don't end up with a horrible step in the port under the valve. Basically the port design for a b cast must be for larger valves, when the seats where cut for the smaller valves it has left a big step. with a std blue heads this is not the case. I will attach some photos when I get a chance.
Wondering if holden ran short on std blue castings and used a few b cast on 4.2's at some stage.

Is it not a case of it just not being throat cut?

If it is different it's likely a case of the casting guys using the wrong moulds or just didn't have any left so improvised and cast it how you see.

 

[Engineresto]

B mark on heads.

 

[Engineresto]

 

[Engineresto]

Casting number on heads.

 

[Engineresto]

This is a photo down one of the exhaust ports. Hopefully you can see the step i am referring to just under the valve. Inlet is similar.