One dog bone was used to retain a pair of hydraulic roller lifters to prevent the lifters from rotating which would destroy the camshaft.

The block was modified to accept a hydraulic roller cam arrangement using what are called dog bones to retain the hydraulic roller lifters. Among the changes was a one-piece rear main seal and, in passenger cars, these engines received hydraulic roller camshafts. In 1986, GM upgraded the small-block in several ways. It is listed under PN NAL-12681429 at Summit Racing. The least-expensive and still popular small-block Chevy crate engine is a built-in-Mexico hold-over from the traditional two-piece rear main seal engine configuration that started in 1955 and ran until 1985. A little history on the small-block Chevy is in order here. The hydraulic roller cam conversion kit that you mentioned is intended to upgrade Chevy’s one-piece rear main seal small-block engines. We’ll go into much more detail so you know why and which engines would benefit from a conversion like this. Unfortunately, the short answer is that this approach will not work. Rather than buy the more expensive roller cam Chevy crate engine, why can’t I just use that Chevrolet Performance hydraulic roller lifter kit - PN 12371042? It seems that adding the roller cam would be the least-expensive way to go. I’d like to upgrade to a hydraulic roller cam at the same time. I am considering buying the basic Chevrolet 350 c.i.d. The only issue is that this can only be used in a factory one-piece rear main seal bock that is machined to accept both the dog bones and the spider. This is a very affordable lifter package priced well under $500. Thumpr Series cam and lifter kits deliver a substantial power increase over an identical hydraulic flat tappet grind without sacrificing reliability or ease of maintenance.This is the factory hydraulic roller lifter package referenced in the story. Thumpr camshafts are available in different grind profiles each one will produce a rough, racy exhaust note and impressive amounts of horsepower and torque within a different rpm range. This gives you a seriously aggressive exhaust note without negatively impacting the power output or streetability of the engine.

The lobe profile and grind characteristics of these Thumpr camshafts use a combination of an early exhaust valve opening, a long exhaust duration, and a generous amount of intake and exhaust overlap to maximize the rough-idling characteristics of the cams. In an ongoing quest to provide you with the performance and sound you demand, COMP Cams engineering team proudly introduces the Thumpr Series cam and lifter kits. COMP Cams is bringing the muscle car sound back, and it's nastier than ever! Let's face it-few things serve to grab our attention at a car show or cruise night more than a car with a thumping, high performance idle.

Chevy 350 cam kit