Plugging the Exhaust Crossover on Oldsmobile Heads

This one of the ways (and the most common way) that I use to plug the exhaust crossover on Oldsmobile heads. I do not recommend this for daily drivers, especially in colder regions, it will effect cold drivability and startups. This modification is used to keep the intake manifold cooler, resulting in a cooler inlet charge. The benefits depend on the build and favor performance engines. I have seen some benefits when used with cams that have LSA's of less than 110 degrees (more overlap). This method will allow you reverse this modification easily by drilling a hole through the plug. Filling the crossover is a lot of work and mostly benefits high rpm race engines, I recommend going to an aluminum head in that application. I prefer this method in performance street / strip engines.