Just a note about Best Gasket and their products and, more importantly, their customer service.
The Best Gasket neoprene rear main seal for Cadillac 390/429 engines leaks within 30 minutes of installation. This has been verified by many people in the Cadillac community. Best Gasket's response to numerous complaints is/has been to ignore them rather than attempt to re-design the gasket or even figure out the exact reason for the failures.
Recently, a friend replaced the seal in his car twice with the Best Gasket seal, both of which failed almost immediately. After discovering that this problem was common to others with the same engine using the Best Gasket rear seal, he sought out NOS Felpro gaskets.
Needless to say they fit perfectly and didn't leak.
I wouldn't use the Best Gasket unless you have a long list of people who have installed it on the same engine as yours and will verify that it works as it should.
Last edited by Otto Skorzeny; 10/23/2021 1:21 PM.
