The Stovebolt Site Forums The Shop Area Engine Shop How to tell a 261 engine?

Is there an easy way to tell a 261 Chevy 6 from a 235 Chevy 6, looking at them? What is the serial number on the 261 engines. The fellow tells me it is a 1954-55 dump truck.
Thanks John

The easiest way, not 100% but almost, is the raised "captain's bars" cast into the block just above the starter motor.

John,

There are 2 or 3 easy ways to ID/distinguish a 235/261 engine.
The "Captain bars can be confusing on 1953/54 235 engines compared to 54 and later 261 engines.

If the Engine Serial Number has not been changed, that is the best code:
Find and post the Engine Serial Number that is pressed into a "ledge" in the block to the rear of the distributor (shown at the link below).
Also, find and post the block and head casting codes and date casting codes for both.

Tech Tips folks. About 1/2 way down in the Engine Tech Tips there is a thread by Barry Weeks that spells it all out.🛠

I'll check it out. Thanks. John

Barry Week's write-up is quite good.

But, I think it does not discuss the oddities of "Captain bars" on some 235 engines (in 1953 and 1954), as posted by 1953 panel in the second post, above.

Engine Serial Numbers are good, but they can be changed/missing.

The block/head casting codes definitively ID 235 vs 261, and the block/head date casting codes definitively ID the years.

Post those codes if you want to know for-certain what you have.