27th Mar 2006, 17:01

THE 403 OLDSMOBILE V8 IS IN FACT A SMALL BLOCK. It shares the same block with the Olds 260 (4.3 liter), Olds 307 (5.0 Liter), Olds 350 (5.7 Liter) and, gasp, the ticking time bomb 350 diesel. The 403 is essentially a Oldsmobile gas 350 bored out with larger pistons (4.351" on the 403 vs. 4.057" on the 350), and no water jackets water jackets between the cylinder walls. This sometimes lead to overheating problems. Although the 403 has the largest piston diameter of any gas V8 engine in a production American car ever, it is not a true big block. Buick's 455 big block V8 of 1970-1976 had a 4.3125" bore with a long 3.9 inch stroke. Olds's smaller V8's (350, 307, and 260) fared much better and are much more reliable. Many of them are still on the road today and still refuse to burn a drop of oil. With relatively good care they can easily make 250,000+ miles before needing a rebuild. More than we can say for the junk GM builds today...

25th Apr 2006, 09:06

Wow, this was very informative!. Any info on the 301 engine in a '77 Buick Lesabre? I'm looking to by one. Any info would be greatly appreciated. Thanks!

28th May 2006, 04:08

An answer to the above comment: The 301 V8 is a Pontiac engine. It was introduced for the 1977 model year and, if I'm not mistaken, was discontinued after 1980. I don't know offhand how good or bad it is, but most of the smaller V8 engines in GM's late '70's and '80's full size cars weren't very powerful... the larger V8 engines generally offer better performance and, if not driven too hard, will actually deliver almost the same gas mileage as the smaller V8's. And therein lies the problem with the small V8's (5.0 liters or less) : they constantly have to be pushed almost to their limits just to keep up with everyday traffic and gas mileage (and longevity) actually suffer as a result. I owned two GM full size cars with small V8's: a 1979 Chevy Caprice with Chevy's own 305 (130 horsepower), and a 1986 Pontiac Parisienne with the Oldsmobile 307 (140 horsepower), and both were very, very slow. I'd imagine that a LeSabre with the Pontiac 301 (135 horsepower) wouldn't be much different. The optional Buick 350 V8 (155 horsepower) or better still, the optional Oldsmobile gas 350 V8 (170 horsepower) would probably offer a better combination of performance, longevity and gas mileage.

15th Aug 2006, 03:42

I have a 1977 buick LeSabre with the 350 V8 Olds, and wanted to know about how much the car is worth? It has less than 96,000 original miles on it. The car is very clean runs and drives like a dream. Does anyone know how to find this info out? Kelly Blue Books only goes up to 86.

28th Mar 2007, 15:26

I've got a 1977 LeSabre, and I love it. It's only got a 350, but I bet I'll give most cars a run for their money. Got the car from my mom, who got it from her mom, who got it from her mom, who bought it off the lot with 5 miles on it. To date it's only got about 23,000 miles. Rides like new, too.

29th Mar 2007, 15:26

Wow, all those moms and only 23k miles. Guess they didn't travel much.

5th Apr 2007, 09:56

I also have a 77 Buick Lesabre. It seems nice for an older, large car. I too am having troubles with the interior clock, I do believe that type of stuff ought to be let go and forgotten. I am missing the two body filler pieces at the corners of the back bumper. I heard that they are almost impossible to find.

As far as power goes, it only has a 350 in it, but it will keep up with the best of them. It all depends on how well maintenced the motor is.

18th Jan 2010, 19:20

I have a Buick LeSabre 1978 Custom. It has a 350 4 boltmain that comes out of a Chevy C-10 1-2 ton 1985 pick-up. And the only problem I have is keeping tires on the car, but I wanna put a cam in it. What's a good one if anybody knows?

22nd Jul 2012, 02:03

Gotta 350 in my 1980 Regency 98, and it's a torque monster. I got 7A heads and a Performer intake. I love the good old 350 Oldsmobile engine.