QUESTION FOR A MOTOR FROM 1956

alexpertkustompontiac1956 · Veteran Member

QUESTION FOR A MOTOR FROM 1956

427carl · A Poncho Legend!

In 1954, a 261-cubic-inch (4.3 L) truck engine was introduced as an optional Jobmaster engine for heavy-duty trucks.

This engine was very similar to the 235 engine, except for a larger piston bore of 3.750 or 95.25mm, two extra coolant holes (in the block and head) between three paired (siamesed) cylinders, and a slightly higher lift camshaft.

This engine was offered as a step up from the 235 starting in 1954. It was replaced by the GMC V6 engine in 1960. The 261 USA truck engine had mechanical lifters and was available from 1954-62. In 1963, the 261 truck engine was available in 4x4 Chevrolet trucks (until the engine sold out).

427carl · A Poncho Legend!

Chevy 235 and 261 L6 engines with full oil-pressure lubrication systems were produced from 1954 to 1962. They were superseded by the 235, 250, and 292 L6 engines, which lasted through the '80s. The 261 was available in 2-ton 6000 or C60 series trucks and schoolbuses, as well as some Canadian fullsize Pontiac passenger cars.

Both engines used the same 3151/416-inch-stroke crankshaft. The displacement difference was achieved by changing the cylinder bore diameter-391/416 for the 235, 311/44 for the 261. A 261 had heavier connecting rods and a bigger piston pin. Most 261s had 7.8:1 stock compression ratios, slightly lower than the 235's 8.0:1 ratio.

GM installed a higher-lift cam with mechanical lifters in U.S.-built 261s, the same one used on the 235ci six-cylinder Corvette. Canadian-built 261s and all passenger-car 235s except the Corvette used hydraulic lifters. Truck 235s had solid lifters. Canadian 261s never received the full-flow oil filter added to U.S. 261s in 1958.

An original 261 will be painted GREEN or YELLOW. The 235s were GREY. Overall external engine dimensions are the same, and a 261 will go right in where a 235 came out. Because they are dimensionally interchangeable, it is not unknown to find a 261 lurking in a U.S. passenger car, even though it was never installed as original equipment.

4SPEED427 · A Poncho Legend!

When I google it, the answer I get is 54 and 55 235.

I hope that helps.

rabbit64cs · Canadian Poncho Superstar!

the 261 has what they call 'captains bars' just above the starter. google that and you'll find tons of pics. It was just discussed here last week.

Beaumont4008 · Uber Guru

Is it a 56 canadian Pontiac ? I thought the 55,56 and 57 pontiacs six cars were 261.

-- Edited by Beaumont4008 on Monday 8th of February 2010 12:13:55 AM

427carl · A Poncho Legend!

An original 261 will be painted GREEN or YELLOW.

The 235s were GREY.

This is your engine GREEN!

427carl · A Poncho Legend!

rabbit64cs wrote:

the 261 has what they call 'captains bars' just above the starter. google that and you'll find tons of pics. It was just discussed here last week.

biggrin

Oracle · Addicted!

My info has it that it's a Canadian 235. The engine number will be found on a stamped pad on the block.

davelacourse · Poncho Master!

alexpertkustompontiac1956 wrote:

I WAS WONDER HOW CAN I IDENTIFIED A 261 FROM A 235 I HAVE NO IDEA WHAT I HAVE IN MY CAR I DID NOT SEE THE BARS IN THE MOTOR, WHERE THERE ARE LOCATED?

Captain's bars are most easily seen on the right (passenger) side of the block above the starter:

Captains Bars.jpg

If you see them then it is a 261 block. If not, you have a 235 (probably installed as a replacement for the original motor which got damaged somehow).

Dave

davelacourse · Poncho Master!

Ick, the photo above included my nasty old starter - here's a better photo, new starter and I cleaned off the motor somewhat - you can see the twin vertical bars in the center of the photo:

Captains Bars.JPG

Dave

long stroke · Canadian Poncho Superstar!

I have had one 1955 Chev and two 1956 Chevs. All were 235 inline sixes and all were painted blue. Hence the Blue flame six. The grey painted inline Chevs to my under standing were the earlier 216 and 235 engines that were before 1955. I have been around 1955 1956 1957 Chevs for over 35 years and have never seen a grey painted inline six in the Chevs. In the Canadian Pontiac 261 inline sixes of the years 1955 to 1962 i have only seen green painted motors. I have never seen a yellow painted motor of those years. Could you please give any further information on the other engine colours that are in question. I love this open forum on these wonderful cars and engines. There is always room to learn. George.

dualquadpete · Canadian Poncho Superstar!

George,I'm going to take a "stab" at the yellow engines. I would think they might be Commercial [truck] or industrial engines!! When I worked at Ontario Automobile on Bay St. in Toronto [ Chrysler dealer] the engine "reman" shop used to paint the industrial engines a different colour than the automotive ones!!! Boy, that was along time ago!!!