The Stovebolt Site Forums The Shop Area Engine Shop 261 engine

Is there some way to tell a 261 from a 235 by looking on the outside?
George

The captains bars and large oil lines are 2 visual indicators as well as the casting number if you can see it. See here for more info.

Captains bars are not a guarantee of a 261, 1953 Power Glide 235's also had them.
1954 261(first year for 261) will have the high mount water pump and Captains bars.
If it has the low mount water pump(1955 2nd-63)and Captains bars then yes, 261.
Unless it is a crate motor, and not stamped, the stamped number next to the distributor is best way.

Dave's caveat is absolutely correct. I left those details out for the reason that I believe there are at least a dozen 261's in existence for every one 1953 powerglide 235 block sporting this new (at that time) method of casting identification. Any comments on my ratio guess?

I buy your ratio.

I recall two posts that ID'd as 1953 Powerglide 235. And, I remember discussion about Jim Carter indicating the 54 235 as having the 261 bars (perhaps mistakenly?).

I have seen a lot of 1954 235's and none have had Captains Bars.

I have four in my garage - no captain bars.

IF your engine is one of the late 261s (after 1959?) it will have two HUGE HALF inch NPT holes on drivers side for filter. Those large holes were only on these late 261s, any smaller oil holes and it could be an early 261 or a 235.

Also, I have three engines with the II captains bars, one is a 53 powerglide 235 next is a 55 first series truck 261 and last is a 1961 261.

58-62 Canadian Pontiac 261's have the cast boss to accommodate for the diverter pin and large oil lines but are only machined to 1/8" NPT for bypass use. IIRC the captains bars were only on one side of the powerglide 235's so would it be safe to say if they're on both it's guaranteed to be a 261?

Next time I work on or see a 53 I will confirm whether the Captains bars are on both sides.

I have a 53/powerglide and it only has captains bars above the starter (none on the manifold side).

Carl, I was just noticing in a picture I have of a 1953 Power Glide 235 engine that it also has the Captains bars on the passenger side.
Just like the 1954-63 261 the bars on the passenger side are hidden behind the manifold.
In this linked picture you will see the Captains bars just below and too the left of the center intake port. Just to the right of them are the last three digits of the casting number, in this case 911.

Dave , are those captains bars or the number eleven, below and to the left of the center intake port? Where are the captains bars located on a 261 and what do they look like? Keep in mind that I don't know very much.
Carl

"captain bars" on intake side

"captain bars" near/over the starter

(from Jim Carter's article on the 261 - JC says "The one exception is the early 261 produced in 1954 to mid 1955. It has only one "Captain Bar" above the starter but keeps the pair on the left side.")