Hello / my stock 401 nailhead in my Buick Electra 225 Year 1960 will get a overhaul. I will buy the Egge Kit with pistons and cam and valves and all the other stuff. Some pre owner of my car puttet the wrong ( a bit too long) pushrods in two of my cylinders and now the valves on that two cylinders touched my pistons and damaged my heads ( valve seats). Now that I need to rebuild my engine I think about boring my stock 401 up to 425. Is that possible is just the bore diameter different and is there enough space to the water channels? Is the crankshaft the same on the 401 and the 425? Are the connection rods in the 401 and 425 the same? Is it a good idea to put in my heads the rings for driving unleaded fuel? Did anyone do the same rebuild like I will do and has any important informations for me? I will add a picture of my damaged head, so you can see what happened... Thanks / and safe & keep the nailheads!!!!!! Bye Herby Germany Black Forest
Consider these threads: http://www.v8buick.com/showthread.php?252464-Need-Help-Nailhead-help!&highlight=bore+401+425 http://www.v8buick.com/showthread.php?238671-401-bored-to-a-425&highlight=bore+401+425
I didn't read Jim's links, but a 401 will not bore to 425. I suppose you could bore into the water jackets and sleeve it, but then you run into block strength issues. I would be very careful as to the valve seats. There isn't much room before you hit the water jackets. Do not attempt to install hardened valve seats; I think you call them "rings" for unleaded gas. The factory seats will stand up pretty well to unleaded - you probably aren't going to drive it 30,000 Km per year anyway. If you try to install replacement seats, I will guarantee that you will destroy the heads. The 401 and 425 rods are dimensionally the same. I think that they will interchange. The principal difference between the 401 and 425 is the bore. Essentially, the blocks and pistons differ, everything else will interchange. Note: I am not positive about the heads. My guess is that they will.
the fellow in the previous thread was right about puttin seats in your head,first the lead in leaded gas acted as cushion for the valves when they closed on the seats,hardend seats are overrated because,buick cast iron has a high nickle content making them strong,unless you are going to have contiuose operation at a high stress level you dont need hard seats,ther are alot of street cars with alot of miles on them runnig just fine
