I have recently had installed a Gen 4 engine with the PD42J carburettor. My experience has been with with the Bing carby up until now. I assume that the PD42J is pressure compensating. The Bing had a tube from the carby to the air filter box as part of its operation. I cannot see this tube on my current setup. Am I missing something or does the PD42J operate differently? I’m having trouble finding reference in the Jab documents .
The PD42J is pressure compensating. The balance tube is incorporated into the induction tube (cobra head) that comes with the engine. More details can be found in the Gen 4 engine manuals.