The Stovebolt Site Forums The Shop Area Engine Shop what motor do I have

Hello I am confused as to what motor I have it is in a 1961 chevy apache 10 4x4. I asume it is a 235 but not positive,I've heard it could possibly be a 261. I cant read the numbers on the block but i did get the numbers of the head and hope someone out there can help me out. here are the numbers on the side it reads, 23 848 850 and on the top it reads con9, K 21 D, and GM23 hopethis will help somone help me as I am in search of a new headas mine has a major crack in it. thanks for your time

if you need a new head anyway, pull the old one and measure the bore - 3-9/16 = 235 and 3-3/4 = 261
also I've been told the threaded oil pressure sending hole in the drivers side of the block is 1/2" on 261, but smaller [3/8?] on the 235

Bill

It was common practice to put an 848 (hi compression 235) head on a 261 to up the compression, most knuckleheads didn't drill the steam holes and voila a cracked head.

You need to get the casting number off the block, heads can be swapped and are not good for identifying motors.

Chris

The block casting number should be raised letters in the area of the starter. You can go to www.inliners.org for the casting number lookup.

Also, most 261s have a raised set of captains bars just forward of the starter.