New to the forum and I hope to spend a bit more time here as I eventually turbo my 94 m edition. In going through my newly acquired car, I ran a compression test and found the previous owner ran a helicoil into one of the spark plug tubes. It wasn't set right and came out with the plug. The head gasket also seemed to be leaking due to the condition of the coolant so I decided to just replace the head. I found a decked head on marketplace for a price that is almost what it would cost to have mine machined. The only concern I have is that it looks like the machine shop took a lot of the surface of the head off. I don't want to up the compression too much or end up with an interference motor. What do you think?

 

What is the distance from the valve cover surface to the decked surface?

 

I don't have access to the head. I'd be buying it sight unseen except for the pictures and shipping it(sounds crazy now that I type it out).

 

There’s something like .060 or .080” of clearance in a stock bp05 head. It would have to have been cut pretty extremely to become an interference motor and/or change the compression an amount that would matter. Have you asked the seller how much was removed when it was surfaced? Machine shop should have given that number to him. Also this would be a great time for you to upgrade to a bp4w head.