Small Block Chevy Engine - Build Your First Engine - Tech

While old-school mechanics had to hassle with leak-prone rubber or cork end seals, today a bead of silicone sealant does a far better job of containing oil. Johnson calls it silicone welding because the application technique involves a push-pull-push-pull movement that's like welding, for a wide, dense bead, free of air bubbles and a consistent width for maximum effectiveness.

Though an HEI is good for general street/ strip use, the large diameter doesn't fit the firewall of an early Chevy Nova. An MSD small-cap Pro Billet distributor solves the problem while offering a wide range of advance curve tuning. JMS says the box-stock heavy-advance springs (in pliers) don't allow full advance until well over 4,500 rpm, so they are replaced with lighter springs taken from the tuning pack included with every distributor. With the blue/silver spring combo shown here, full timing advance is in effect by 3,000 rpm.