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This might be better on another forum hereabouts, but I figured I'd ask...

Curiosity question...If one has a good 1.7L head with good 33mm exhaust seats, and wants to cut them to fit 34mm valves (1.8L standard), can it be done? I guess the question is, do standard 33mm VW T4 exhaust seats have enough "meat" to be opened up for 34mm valves?

That would depend on the existing valve margin. For those who dont know, the "margin" is the height above the outer flush edge of the seat as it sits in the head....that the valve will rest at after cutting. Everytime you cut the seats for clean seal...the valve sinks lower into the head...because the angled ring you ground onto the valve gets larger in diameter.

When you run out of margin the head of the valve will be too close to the actual metal of the head. Also, it weakens the seat.

The real problem I see is not that the seat can or cannot be cut for 34mm...but that it is a stock seat...and should be replaced anyway. If this is a low milage....known condition...well cared for head....sure. Go for it. If it spent time in a 914 or a bus....get new seats. Ray