I want to know if a 401 can be bored to a 425. I've been researching around about the 2 engines I have. What I have is 2 engines with the 425 #s on the block, but the bore measures up as a 401. I think the crank and stroke are the same and I know the bore is larger on the 425. I'd hate to waste a good block just to fine out it wouldn't work. They aren't making them anymore!
Welcome to the group. I'm not an expert but I believe it's been done before. You would have to sonic test the block to see if there is enough meat in the bores but most people will say "no, it can't be done". I also believe you will get a better answer if you post this in the Nailhead forum instead of the Paint forum.
Clear as Mud I think the general answer is no. While the external casting is the same between some of the 401 and 425 castings, the internal core seems to be different and has measured different between the cylinders inside the water jackets. The 425 has less room between the cylinders. That supports the idea of an internal 425 core cast with larger internal and external cylinder diameters. Here is a thread that also seems to support that idea: http://www.v8buick.com/showthread.php?s=&threadid=10623 . You could have it sonic checked just to be sure as Bill had stated. It would be interesting to see what you find out. Cheryl
401 and 425 nailhead bore info Thanks for moving my last measage. Sorry about that. I was looking in the color is everything post when I thought of the question. I'm trying to figure this thing out. Yesterday was my first time on this site and I decided to register. Thanks for the info. I'd like to do something neat with these engines. My dad and uncle are wondering the same things about the 401. Together we have five 401s, from 62' to 66'. Two are in 66' GS's and one in my 65' GS.
