I used to work for dresser ind. , the pipeline engines compressors had poppit vales in disc shaped housings , with around 27-30 (cant remember for sure) , In each disc , had to grind those seats for more years than I want to remember , hated every minute of it , probly ground more than u guys have seen , altho they wern`t performance type stuff , some times 30-40 discs in a single compressor , 4 to 8 compressors on each engine , depending on how big it was .
They had v-16 and v-20 engines that were bigger than a lot of buildings , they were so big they couldn`t be shipped assembled , much less w/ the compressors bolted on the side of them. Best thing I ever did was get away from that place !
If I need any head work done , I have a friend that has a serdi machine -------------
