That makes me wonder. Because i have a 68 318 with 273 crank. And what i can see on my order history is that the mainbearings iwe used is supported for a 74-up 318.
But the crank hade been grounded .10
Iwe ran the motor for a short while, then sold the car.
Maybe i have to check over the bearings then.
The undersize grind on the crank would not change this. The issue is the shallow relief ground in the main cap and web on both sides of the #3 main... that relief has to be wide enough to allow the flanges of the thrust bearing to fit.
This whole discussion made me go out and measure a 1968 273 block. It turns out that the machined relief for the thrust bearing flanges in that early block is plenty wide enough to accommodate the later, larger diameter thrust bearing flanges, with room to spare. So, swedish viking, your engine is probably just fine!
Now, I cannot say this was the case in all SBM blocks prior to 1974. But it may well be that this was the case forever, and they just decided to put in a wider thrust bearing flange for other reasons, like better wear or heavier transmission thrust or something. It is interesting that this change took place in the same year that they changed the 318 to the larger heavier rods.
