[wilf]

Chris - I read both posts twice, and I am missing something. If you are both plumbing your PCVs into the full vac port on the carb base/inlet manifold, what is the difference in the set up between yours and MarkT's, that stops "too much" vacuum being available?

I can't see that your other breather being to free air, and his being in the air filter should make any difference (no additional vacuum inside the air cleaner?)