Technical Weiand heads

Picked up a set of wieand heads at a swap meet this weekend.At the bottom of the head between the fins there is a F B embossed there can anybody tell what that means?

 

Should be FR at the bottom of the heads not FB. The FR stands for racing.

 

Yes it is F R . any more info on these would be helpful

 

A full picture of the other (combustion) side would also be helpful.

 

As Quickchange mentioned....Some have the Comp. Ratio stamped under the water neck...

 

Thanks for your help