Once in a while a new product comes along that captures your attention; so it was for us when we first caught wind of the new main stud girdle from Chenoweth Racing Enterprises (CRE). The notion of a main girdle is not an all-new idea; the use of such an arrangement has become standard practice in building other makes of engines. However, for big-block Mopar applications, an easy-to-use, readily available, main girdle has been a product that was sorely lacking. The girdle kit from CRE is aimed at filling that void, and we wanted to try one first hand.
Why even consider adding a girdle as a part of your big-block build? Looking at the standard big-block bottom end, with the deeply skirted block and webs running from the main bulkheads down to the pan rails, it would seem that the Mopar wedge takes the cake as the beefiest bottom end you could get. Appearances can be deceiving, however, and, at some point, problems begin to appear, which can lead to disastrous results. The problem is main-cap and bottom-end stability as power levels get higher, with the result being hard-to-control cap walk, and, in the worst case, the main webs of the block developing cracks, making scrap out of that iron block.
At street power levels, right up to the low-to-mid-500hp range, a studded stock-bottom end is reliable. Push power up into the 600-650hp range, and, even with studs, cap-walk and main-cap reliability will be borderline at best. At power levels higher than this, main-cap instability becomes a fact of life, and block failure is just a matter of time. Up until the '80s, before the explosive growth of serious aftermarket performance parts, a well-built hot street 440 with a set of factory iron heads would make between 425 and 500 hp, with the upper end of that scale being the exception rather than the rule. What's changed the playing field was the development of high-flowing cylinder heads, which dramatically increased the power levels routinely achieved, even in street applications. In a typical bracket application, today's big-block combos routinely get to power levels that marginalize the bottom-end reliability. In recent years, stroker combinations have become mainstream, both for street and track combinations, which places even higher demands on the reliability of the bottom end.
To help production big-blocks cope under the strain, builders now will routinely upgrade the main caps to aftermarket units, with a couple of different approaches by various builders. Billet steel or high-strength nodular iron caps to replace the production main caps are favored by some looking for an edge in brute strength. Other builders prefer to soften the hit to the main structure by employing aftermarket aluminum main caps, with the higher compliance of the material serving as a sort of shock absorber, reducing the impact stress on the block structure. In race applications, filling the lower block's water jacket is another move aimed at strengthening the structure. The stud girdle is just an additional tool that further expands the components available to beef-up the production bottom end. While it isn't going to turn a 35-year-old passenger car block into the equivalent of a good aftermarket race block, the main girdle may be just the ticket to peace of mind when running a production engine to power levels never contemplated when these blocks were poured.