Need help id'ing BB head

[PettyBlue72]

I have a 76 400 that I believe has been rebuilt at some point. There are several things that tell me this motor has been rebuilt but the first giveaway is the motor has 2 different heads on it. It has 1 902 head and 1 head that has part number 3751213. What is this head and is it the same as a 902 head and if not what are the valve sizes, flow etc.

Thanks in advance,
Joe

 

[Red63440]

3751213 400/440 Motor Home 1973 2.08 1.74
The 902 head came out in 1974...

 

[PettyBlue72]

Thanks Red63440, that was quick. What is the valve size for the 902 head?

Joe

 

[Red63440]

I am fairly sure they are the same size as the 906.

 

[greenmonsta79]

I think they all have the same flow characteristics (not spectacular) I was always told 906's were best but that is just not true, aside from non hardened seats they flowed almost exactly like a later 452 head, I have also pulled original motors apart and had different casting heads on them.