S54 schrick- build and timing issues.

[bigjae46]

I would have figured out how much the machine shop took off the head and the block before making an expensive guess. That would been a key clue. But curious to see how it turned out...hopefully well!

[BMWfanz]

Any updates on this, sorry for digging up old thread. Will be going through something like this next year as well.

Running great now. I've done 1000kms running in, done HTE retune. With exhaust porting and increased compression ratio (due to head surfacing- 12.1 CR)- Hassan retuned vanos, corrected AFR- car is pulling really good on high RPMs. I don't really know how engine builders say that there is a lot of clearence between piston and valve on 288 12.5 lift. I think there is a really low clearence build on even stock engine without surfaced head and block. I've not found vanos test results on cammed cars.

[BMWfanz]

I would have figured out how much the machine shop took off the head and the block before making an expensive guess. That would been a key clue. But curious to see how it turned out...hopefully well!

For first build-surfaced block and head -surfaced head for 0.3mm, block- 0.1mm (on this setup- valves contacted to pison on vanos test). Second ruild- surfaced head 0.15mm. For safety run i've increased releifes on custom pistons (+1.5mm intake +2mm exhaust)

[Slideways]

For first build-surfaced block and head -surfaced head for 0.3mm, block- 0.1mm (on this setup- valves contacted to pison on vanos test). Second ruild- surfaced head 0.15mm. For safety run i've increased releifes on custom pistons (+1.5mm intake +2mm exhaust)

According to a post on m3cutters, 0.3mm skimmed off the cylinder head is the max for a factory Elring gasket. Most are able to stay below 0.2mm. Your's was 0.4mm, so a thicker Cometic head gasket might have avoided the piston to valve contact.

[BMWfanz]

According to a post on m3cutters, 0.3mm skimmed off the cylinder head is the max for a factory Elring gasket. Most are able to stay below 0.2mm. Your's was 0.4mm, so a thicker Cometic head gasket might have avoided the piston to valve contact.

Yes, but after first build i was running on stock cams and all was ok. After 6 years i've decided to go for CSL airbox and schricks- forgot about piston to valve clearence cause i've changed engine builder and this story ended with second rebuild and custom pistons.