Early in Twin Cam production, five holes were added in the front cross member to allow easy access to the front bolts of the engine sump. If you have an early Twin Cam car which does not have these holes, you can add them as prescribed by the factory. From gathered statistics car no. 600 does not have the holes and 602 does, so it appears that the first 100 Twin Cam frames did not have them.


On 23 Mar 2020, Rich Colwell wrote:
"Mr. Jim Alcorn sent me a template for the bottom holes. I lined these up, and drew my center-points after punching a 1/16" hole through the center of each of the marked template holes. I then got paranoid, as they did not appear symmetrical with the two larger holes in the cross-member.
So you will see a second template, made from a sump gasket. I took 1/4 in. aluminum rod, cut them to 7 in. lengths, threaded one end, and then suspended the cardboard+gasket from the aluminum rods that were threaded into a few select sump bolt holes. This gave me the confidence to drill. I center-punched, and then drilled the bottom.

The top was a different story, as that was not parallel to the bottom. I had issues with trying to get a 1/4" drill to bite, as it wanted to wander. Secondly, I did not wish to drill 1 in. holes from the bottom, as they would appear as ovals on the inclined top surface. I was able to drill the 1/4" starter hole for the top center from the bottom. I then drilled it out from the top, resulting in a round hole. the remainder we drilled from the top using center-to-center spacing from the sump bolt holes, and maintaining angles. Measure 3 times, drill once. They appear to line up when looking straight down".