If you're serious about building power, especially power that lasts beyond one dyno pull, you know that a two-bolt main block just doesn't cut it. High-horsepower motors throw the crank harder, and with a measly two bolts holding your guts in, eventually something is going to fly out, crack, stretch, or flex. When it comes to strength and bottom-end survival, four-bolt mains are a necessity. The only problem is that most of the four-bolt main blocks are either still in use or are already in someone else's hot rod. But here comes the good news: There are plenty of two-bolt main small-block Chevy 350s and 400s just waiting in your local junkyard, and Milodon makes a two-bolt to four-bolt main conversion kit, so you can play hardball with less hassle and less money. The kit will actually make your engine stronger than a factory four-bolt. Milodon's kit comes with much bigger and stronger main caps. The splayed outside bolts connect to the block in a much meatier area than a stock four-bolt main cap, decreasing the likelihood of cracking (which four-bolt 400s are notorious for). PAW in Chatsworth, California, sells the kit and offers to install it as an extra when you buy one of the company's engines (that way you don't have to make an extra trip to the machine shop). We went to PAW to take photos of the conversion on a two-bolt main small-block Chevy. If you're putting together a small-block 350 or 400, Milodon's conversion kit is a great idea. It's not the type of install that you can do at home (unless you've turned your guest house into a machine shop), but with the right tools and gauges, your local machinist can do the conversion for you very easily. The three center main caps were torqued down to spec, and the air gap was measured with a feeler gauge. Clearances of 0.001- to 0.003-inch are necessary. The three center main caps were torqued down to spec, and the air gap was measured with a The caps were cut until the desired clearance was achieved. The caps were then re-torqued and double-checked with the feeler gauge. The caps were cut until the desired clearance was achieved. The caps were then re-torqued With the sleeve in place, a handheld drill was used to bore out the block material. The new caps were bolted back on and torqued to spec. They were then align-bored and chamfered. The new caps were bolted back on and torqued to spec. They were then align-bored and chamf Milodon's kit comes with a special sleeve that's inserted into the new cap. The main cap actually serves as a guide for the drill. Milodon's kit comes with a special sleeve that's inserted into the new cap. The main cap a After the block was drilled, a tap was used to create the threads for the bolts. The caps were finished off with an align hone. A dial bore indicator was used to make sure that each cap was the proper size and was perfectly round in shape. A dial bore indicator was used to make sure that each cap was the proper size and was perf Much better. Here you can see how wimpy the two-bolt main caps look in comparison to Milodon's four-bolt mains. Milodon's four-bolt conversion kit is worth its weight in gold. Here you can see how wimpy the two-bolt main caps look in comparison to Milodon's four-bol Because the new caps are so beefy, a notch had to be machined out to clear the dipstick hole on this particular engine. Because the new caps are so beefy, a notch had to be machined out to clear the dipstick ho SOURCES PAW 21001 Nordhoff St. Chatsworth CA 91311 8-18/-678-3000 www.pawinc.com Milodon 2250 Agate Ct. Simi Valley CA 93065 805-577-5950 www.milodon.net By Taylor Vlahos Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!