So I've currently got a late B20A head with totaly worn exhaust valve seats. So in order to be able to use it, it needs hardened valve seats put in.

The intakes on the head are the larger 44 mm ones, and look just fine. For the exhaust I could just re-use the 35 mm valves, but I started thinking I might go a bit bigger. I have some volvo 38.5 mm exhaust valves lying around, which I'm tempted to use...

My question is: would that be a good idea? I mailed John Parker for some other questions, but also very briefly discussed the 38.5mm valve option. He said "when going to 38.5 without other appropriate changes will give less flow." Offcourse I will also work on the port, but it will not be a fully ported race head either, just some basic porting.
Should I perhaps get some 37mm valves? Compared to the 44mm intakes, 35mm exhausts seems like a small valve / ratio to me.

Any opinions / experiences?

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