Correct, KG stage II is 44/37 and stage III 44/38.5. The head I would be building would be 'stage II-ish'. The thing I wonder about is: Do they use the 44/37 combo because it works the best, or because it's easier and cheaper to use the 37mm valve and since the 38.5mm does not give extra perfromance, OR, do they use 37mm because the 38.5mm valve gives less performance?

Using the 38.5mm would be cheaper since I have a set of them lying around, doing nothing then collecting dust, where I would have to buy a set of 37mm ones.

Maybe someone can even persuade me to stick with 35mm, but there are very little hard data and facts that I know of, on what is good or bad. I mean, why should I not use the 38.5mm valve on only a mildly ported head? Flow velocity around the valve goes down, but is that bad? And how/why is that bad?



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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)