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| | | | Joined: Sep 2004 Posts: 24 New Guy | | New Guy Joined: Sep 2004 Posts: 24 | WILL A HEAD OFF A 261 MOTOR(1954), WORK ON A 235 MOTOR(1955-1957)
HEAD NUMBERS= 3
499
CON 12 H282
3835499
GM4
ENGINE NUMBERS= 2 004
CON4 J265 3837004
THANKS FOR YOUR REPLY IN ADVANCE. MJ
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | What is the block casting number of your 261 motor?
The head casting number is for a 50-52 216.
| | | | | Joined: Jun 2005 Posts: 388 Shop Shark | | Shop Shark Joined: Jun 2005 Posts: 388 | Here is a comparison of a 235 and 261 head, from the famous Racer Brown/Frank McGurk article in the May 1955 HRM. I have put a couple of 235 heads on 261 blocks, so one should be able to put a 261 head on a 235. There will be a loss in compression ratio, as the combustion chamber volume of the 261 head is larger than that of just about any 235 head. You will need to use a 261 head gasket. All this assumes that you have a 261 head. The steam holes will tell for sure. Hoyt | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | First, it would be advantageous to determine the years of your head and block. - The head date casting codes might be found on the top of the head, between the 4th and 5th cylinders' valve springs. (manifolds side of the head) - The block casting ose might be found on the lower left of the starter side of the block.- The engine ID is pressed into the block in the ledge/boss to the left of where the distributor enters the block, As Hoyt stated, a 261 head and 235 block will bolt together, if they have the correct bolt pattern. Do they both have 18 head-bolt holes? If either has 15 holes, they will not bolt together and you are mistaken regarding the year of manufacture. Even if you have 18 bolt head and block, it is not necessarily a "perfect match". They will bolt together, but you might have to make an adaptation to arrange for block oil to reach the rocker arms. ( see this discussion ) | | |
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