I have a b35 head and it has been shaved .017in (.43mm ) and was wondering what compression ratio would be with US b34 block. All info much appreciated. And also head gasket suggestions would stock head gasket with arps hold up?
You'd be looking at 7.66:1 roughly, with a stock size gasket. I recommend dropping the cash on a MLS gasket, if you're dropping the coin on ARP fasteners, what's a couple hundred extra on a gasket? The cool thing about MLS gaskets is that you can re-use them.
There is a lot of theories on headgaskets, and I have seen many do quite well with stock gaskets. I've seen 3 series with 622whp that still ran stock headgaskets. Food for thought.
The M30 seems to be harder on head gaskets than the M20. I ran 21 psi on a stock head gasket with studs for a year and a half. And I've seen M30's blow stock head gaskets with studs at 8 psi.
The stock headgasket high power bmw's were all o-ringed to my knowledge. I did an o-ring and stock gasket setup for my own motor. I did use ARP hardware.
The lower compression isn't really necessary unless you're chasing high boost levels. At that point you'll need MLS, studs, and possibly pistons. The stock ring lands start to crack somewhere just north of 20 psi IIRC.
