Main studs are an often-overlooked part of an engine rebuild. As critical as rod bolts and just as important as cylinder head studs, main cap studs are all that hold the crank and main caps accurately in place. Your crankshaft spins at thousands of revolutions per minute for hours on end, and the only things that stops it from whipping and self-destructing are the main caps, studs and nuts. Racers have repeatedly asked me to supply racing-quality main studs of high carbon steel, and - most importantly - with rolled threads. Those available from the usual suppliers are made from mild steel with imprecise and relatively weak cut threads, and racers have complained that they are marginal at best.|
I have therefore custom-commissioned a proprietary run of ARP main cap studs. My new studs are made of the finest 8740 nickel-chromium-molybdenum steel with a black oxide finish, heat treated, and with rolled threads yielding the greatest strength and precision. They come - as do my similar and equally-impressive head studs - with an internal hex on the end for easy installation without the possibility of damage to the shank, and are supplied with custom-made ARP 12-point nuts designed and manufactured for me specifically for the XPAG/XPEG engines. These main studs do NOT come with lock-wire holes, which the engineers at ARP felt would significantly compromise the integrity of their studs. In discussion with the engineers, they assured me that when properly installed and torqued, the clamping force of the ARP nuts and studs is far superior to the original factory studs supplied with our engines some 70 years ago.
Another advantage of having them made with superior rolled threads is that the critical shoulder where the stud contacts the block is more perfectly formed than would be possible with cut threads - in this location, rolled threads provide up to twice the clamping strength of cut threads. In fact, ARP is so confident of their design, manufacturing standards and quality that they recommend a higher torque value - 74 pound feet rather than the stock 63.
In short, these are the finest main studs obtainable, and will last a lifetime under even the most severe racing service. The cost of a complete set of six studs and nuts is $180, including shipping within the US. For foreign postal costs please inquire.