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? THE ONLY THING I FOUND IS THIS NUMBER
3835913 GM
WELL AT HIS MOMENT IM CONFUSING IF MY CAR HAS A 261 OR A 235 ANY WAY TO FIN OUT? IS THIS NUMBER HAS ANY MEANING TO YOU? THIS NUMBER HAS TO HAVE RELATION WITH MY VIN NUMBER? 62039622488 THANK YOU ON ADVANCE FOR YOUR HELP
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).
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 They were superseded by the 235, 250, and 292 L6 engines, which lasted through the '80s.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.
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:
Dave
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1956 Pontiac Pathfinder 2dr sedan, 496 - dyno'd 545 hp, stick shift, 4.11 posi - Hot Rod
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.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
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!!!
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Some times I wake up GRUMPY, but today I let her sleep in !!!!!!!!BLACKSTOCK Ont.
1956 Pontiac Pathfinder 2dr sedan, 496 - dyno'd 545 hp, stick shift, 4.11 posi - Hot Rod