What would make us open up the completed bottom end of our 446 street mauler project? How about a bolt-on bottom-end reinforcement that promises to substantially increase the power handling capacity of the stock 440 mains, and banish main cap walk at the power level we are looking for. The big-block Mopar stud-girdle kit from Chenoweth Racing Enterprises (CRE) is too appealing to pass up, and the theory behind it is something we buy into. The possibilities were intriguing enough to drop our freshly installed pan and pick up a good measure of peace of mind.
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.
Clearing the way for the CRE main girdle installation required removing the sump and windage tray, and then getting the pick-up tube out of the way. Note that our 446 was already fitted with main studs.
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.
To fully appreciate the main girdle, it helps to look critically at the bottom end design, and the forces that contribute to the problem. The deep-skirted block and its webs look impressive, especially compared to an engine with a block that ends at the crank centerline, but in the real world, it doesn't really seem to contribute to the power-handling capacity. The main caps are cantilevered out from the crank saddle surface, just as in a small-block or (we hate to say it) big-block Chevy, and all that structure and material below the centerline structurally adds next to nothing to the support of the crankshaft. It's not until the main cap is tied into that structure that it imparts a significant level of reinforcement to the bottom end. The cross-bolted design used in the Hemi accomplished this, while the main caps in the standard two-bolt passenger car blocks just hang in the breeze. Deeply skirted blocks with the mains tied into the structure represent a substantially improved layout, and this configuration has been embraced by engineers in a number of the latest engine designs.
The girdle is a quarter-inch-thick steel plate, CNC water-jet cut to precisely match the block's mains and pan rails. Included is a complete hardware kit, featuring top quality ARP studs, and the required shims and spacers for a bolt-in installation. A heavier 31/48-inch-thick kit, without provisions for the dipstick or internal oil pick-up, is also available for drag engines with external oil pick-up. | 
Main girdles have proven their worth in many non-Mopar engine applications, but, until now, a complete kit for the big-block Mopar hasn't been readily available. CRE has changed all this with their main girdle kit, which contains everything to brace-up the bottom end of the production two-bolt main block. |
At the rear of the block, the rear main seal retainer needs to come out to get to the rear studs or bolts for replacement. Be prepared with new side packings for reinstalling the retainer. | |