Crankcase Vent Covers

This is the crankcase vent on the ABA engine. It located where the warm-up regulator (a.k.a. control pressure regulator) would be located in A1. If it is removed, the opening in the block must be covered with a plate machined to fit over the hole and allow you to mount the warm-up regulator in its normal spot. You also have the option of leaving the vent in place and locating the warm-up regulator elsewhere. The warm-up regulator controls the fuel mixture as your engine warms up. It provide a richer mixture when the engine is cold and leans it out as the engine warms. If you move the regulator it may affect its operation as waste heat from the engine block assists an electric heater inside the regulator. If you move the regulator your engine may run richer longer as the engine warms up and in very cold weather may run too rich all the time. In my opinion, this is a no-brainer, it took me less than 45 minutes to make a cover plate and gasket. It probably would have taken at least as long to relocate the warm-up regulator. In my installation, the round hole on the left is capped off with a 40mm frost plug and the other hole is covered with a 1/4" aluminium plate. Here's the finished plate, ready to install.

Here are all the tools and materials I used to make the plate and gasket.

This picture shows the mounting plate for the warm-up regulator taken from the old engine is bolted to the cover plate (painted black) using Allen bolts with low profile heads. If you wanted to, you could make the cover plate out of 1/2" aluminium, recess the lower left bolt and mount the regulator to the cover plate.