Is there anyone who could help me to figure out if the engine is a 401 or 425? The car is a Buick Electra convertible 1965 but I dont know if its the original engine or if has been swapped earlier. As you can see at the pict the code at front passenger side is ending with 529 and there is a W before but there is something between and even before the W.. The casting number ends on 704= 425? I thought I read somewhere that convertibles only hade 401, wrong? Thanks in advance!
Also, the casting number is listed for a 1963-1966 425 here. The 401 and 425 share some external casting numbers, but yours is exclusively related to the 425. Cheryl
Ok... so you think its a 425. My casting number on the intake manifold are 1375549 cant find it in the document?
That casting list is not all inclusive, but what is there is correct. I clearly see KW and the date code in you other picture. That also represents a 425 (1964 single 4 bbl) as listed here. So, your cross check also indicates 425: Enjoy it! I would next check the numbers on the driver side of the valley pan rail and see if they match the last portion of you vin number. This way you know that is the original engine in the original car. Cheryl
If you look toward the back of the block just below the distributor if it's a 425 it will have a square trapezoidal hump next to a tear drop shape
