A couple of things to note here: Splayed, billet-steel, 4-bolt mains are an upgrade from the original ZL-1. Also check out the engraved cap. The enthusiastic staff at Schwartz Machine in Warren, MI, who finish each raw casting for GM, began etching each main cap with the "ZL-1" logo. GM didn't ask them do it-they just did it because they understand the history behind the block. They engrave the rear cam plug, too. The pair found the tooling gathering dust in a corner of the foundry. It hadn't been used since the '70s. Though dusty, it was in excellent condition. In fact, with an estimated 300 blocks poured altogether, it was almost new compared to tooling used to make blocks by the thousands. With super-strong "G2" steel liners fitted, the ZL-1 has 4.25-inch bores, which can be stretched to 4.30 inches. According to GM, the block can handle a 4.375-inch stroker crank, too. There are plans for 4.500-inch-bore ZL-1 block in the future, also. With super-strong "G2" steel liners fitted, the ZL-1 has 4.25-inch bores, which can be str Arrangements were quickly made to have the ZL-1 tooling shipped to the foundry that makes current, aluminum GM Racing small-blocks and heads. During the next couple of years, the ZL-1 tooling was cleaned and revamped. Improvements were made on a few of the block's design details before pouring the first "new" ZL-1 block. The biggest improvements included screw-in, O-ringed water jacket plugs and splayed, four-bolt 8620-billet steel main caps. The lifter valley was also modified to accept Gen VI-type roller lifters. Overall, quality and serviceability of the block were improved. This better version of the ZL-1 offers brand-new blocks from the tooling of the originals. The best of both worlds, wouldn't you say? No, the best would be some sort of ZL-1 crate engine. But it's not available... Well, not yet anyway. Oh, wait. We weren't supposed to mention that! Check out the lifter bores. They've been machined to accept roller-style lifters. That way, the popular roller cam setup from a production Gen VI big-block can be utilized for a more street-friendly build-up. Check out the lifter bores. They've been machined to accept roller-style lifters. That way In this photo, you can see that, different from an iron big-block, the top of the cylinder bank has screw-in core plugs. There are four such plugs: two per bank. Also, note the cast-in pedestal, one of two in the lifter valley. The roller lifter retainer, or "spider" as it's also called, bolts to these bosses. They're for use with the production-style Gen VI "finger-style" lifter desgin. In this photo, you can see that, different from an iron big-block, the top of the cylinder Besides its billet, four-bolt main caps and screw-in freeze plugs, the modern ZL-1 features a two-piece rear main seal and provisions for either a regular-sump or dry-sump oiling system. Add a set of aluminum heads and a finely tuned four-barrel, and this motor will make more than 600 horses. Much more. Besides its billet, four-bolt main caps and screw-in freeze plugs, the modern ZL-1 feature « | 1 | 2 | View Full Article By Barry Kluczyk Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!