shoestring
Well-known member
- Joined
- Jun 20, 2009
- Location
- Swampscott, 01907
OK, measured this on an untouched B230 head with a correct base measurement of 146.1mm. That's the distance from the deck to the valve cover surface.
The intake valve is 9.80mm below the head deck, the exhaust is 9.58mm below. A stock head gasket is 1.2mm compressed. That means that if you have a stock engine, and your piston is EXACTLY zero deck, the M cam's exhaust lift of 10.5mm is about as far as you can go. Therefore, the A cam (10.5mm lift int/ex) is going to be ok, but the B cam (10.6mm int/ex) may not be, depending on piston position. Yeah, I know, 0.1mm is very little, but you've got to draw a line somewhere. If you mill the head, whatever you take off REDUCES the maximum lift you can run and still be non-interference.
Anything with 11.0mm or more is definitely interference.
So there you go. Moral of the story is change your timing belt. They couldn't have made it easier.
The intake valve is 9.80mm below the head deck, the exhaust is 9.58mm below. A stock head gasket is 1.2mm compressed. That means that if you have a stock engine, and your piston is EXACTLY zero deck, the M cam's exhaust lift of 10.5mm is about as far as you can go. Therefore, the A cam (10.5mm lift int/ex) is going to be ok, but the B cam (10.6mm int/ex) may not be, depending on piston position. Yeah, I know, 0.1mm is very little, but you've got to draw a line somewhere. If you mill the head, whatever you take off REDUCES the maximum lift you can run and still be non-interference.
Anything with 11.0mm or more is definitely interference.
So there you go. Moral of the story is change your timing belt. They couldn't have made it easier.