Gti6 Head Problems

[Richie-Van-GTi 74 2 Cars]

I have a gti6 engine which came to me in parts but in good faith it was suitable for building. The seller I believe genuinley thought this to be the case. However now I starting to get into it I was going to take the head for skim and clean etc. It has serious corrosion around the various galleries with some going into the boundaries of the combustion chamber sealing rings. The head has previously been heavily skimmed as its right down to the thickness markers. So my question is how unsafe is it going beyond this depth although I dont really want to with 300 degree cams going in. How hard would it be to convert a j4r head into the 6 head? What are the differences beyond valve springs?

[dobboy 231 2 Cars]

I have a very good J4RS head, I don't think it's ever been skimmed.

 

It was a bit of a tapper because I fecked up when doing a belt change.

 

If you're interested put up a wanted add and i'll get you a postage cost etc.