There are little nibs that point straight at the bolt head area of the main caps. On 427 Side oilers that is where the side main cap supports were placed. The cap had a threaded hole in a boss on each side the block had a hole bored in from the outside through the nibs and a space is place between the two and then a bolt through to hold the main girdle tightly in place in those motors.
A little bit of history on those blocks. In 1966 427s were factory rated at 425 horses. A stock 66 fairlane went 10.21 in the quarter with that engine. Made the record books in stock class. That requires over 550 horses to do that. The side oiler 427 pulled 90% of it's power in the 1st 10 degrees of throttle opening that year at Le Mans in 1967 the Side Oiler was outlawed at LeMans so they used the SOHC version instead LOL and won again.
What is most important about that block is its sheer horsepower potential due to the side bolts when made into a stroker. Other companies made girdles that fit over other engine main caps in an attempt to get the strength of that block. Fuelers used them with 4.3 steel cylinders and 5 inch cranks for 580 cid motors.
I can't quit drooling
![Love :love:](./images/smilies/icon_love4.gif)
Sorry for going off the deep end but I have been trying to find one of those for years. My last large stroker used one and the bottom never failed.