VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1928 cylinder head

In the inlet passage on the -28 head,some have a narrowing,(see picture)What are intention of this pieces?

Those pieces are inserted to straighten the flow into the head. Laminar flow has less resistance then turbulent flow. So with the inserts a fractional horsepower increase is possible.

Wondered myself what these were for. Thanks for the enlightenment Chipper

Thank you Chipper

But why 26,5 mm inlet on the shell?
Outside 33,0 mm. More air in, more power out?
Around 37 % less area

I understand your questioning the effectiveness of the inserts. That is why I inserted the sentence quoted above.