i have made at least one post where i said to plug vent holes that are in dist caps. but i didnt think about disturbers that use vacuum going through the dist, DO NOT plug the vent on them, i do not know which ones do that, the chrysler caps i know, small block mopar, V-6-8, big blocks V8 , i think they will be ok with a pluged cap. just dont plug dist with vacuum going through them.