Opinions on 403's?

[G-Body_Vet]

I'd actually like to hear what people think about them that actually own them. Yes, I know they only make 185 hp, yet 320ft/lbs torque in stock form. I've read all there is to read about performance improvements too.

I found what may be a good deal on one and I'm considering getting it for the time being. The low CR isn't such a bad thing when it comes to being able to run 87 octane either. I'm thinking it might not do too bad with the 3.73's and a 200-4R just to use as a cruiser.

 

[olds307 and 403]

They are a big torque upgrade over a stock or mild 350. I had cooling issues, many. Get a good rad, shroud and 7 blade clutch fan. Don't use under drive pulleys and use a heavy duty water pump.

 

[DRIVEN]

I'm curious about real-world opinions too. Been looking for a deal on one for a while. I've never actually owned one but have driven a couple stock TransAms that had them. My impression is that they'd be more fun with good gearing.

 

[G-Body_Vet]

I'm curious about real-world opinions too. Been looking for a deal on one for a while. I've never actually owned one but have driven a couple stock TransAms that had them. My impression is that they'd be more fun with good gearing.

I recall a few things from 10+ yrs ago. I had 2 friends that owned them. One was swapped into an early 80's Ninety-eight and it ran pretty well, especially once you were doing 70+mph on the highway. The other one was in a '77-79 Ninety-eight and it was a dog. I remember driving a g-body Cutlass with one and it was literally blowing oil out of the passenger side exhaust pipe....but it would still fry the tires at will.

The thing that's always piqued my interest in them is that they're light and make torque. But like you said, I also think the right gearing is what really wakes them up.

 

[marcar1993]

I love mine. I only pulled it because it was an unknown motor with unknown miles I threw in the car and abused for 3 years and the low oil pressure got to it. This 350 in its place doesn't hold a candle to it. My 403 is currently tucked in the corner of the garage awaiting $ to do machine work and make it all fresh again so it can go back in the car.
They are great motors, fit like a 307 with the most cubes you can get in a small block package. Just make sure you're cooling system is up to snuff and you'll be good! Enjoy the torque!

 

[olds307 and 403]

Gearing helps, 2.56 to 3.42 gained .6 in the 1/8 mile. A close to stock 403 will burn tires, even with 2.56 gears, mine did. Slowly doing a stroker build on mine.

 

[DRIVEN]

...and the low oil pressure got to it.

What's the common cause of that? I've seen quite a few 403s for sale over the years that seem to have "ran great when pulled but had low oil pressure".

 

[G-Body_Vet]

I hate to let the cat out of the bag too soon, but the reason I started this thread is because I came across one that was pulled almost 9 years ago. It's been sitting inside a body shop the whole time and is supposed to have less than 50k miles. The owner pulled it in favor of a SBC crate engine during a restoration, had a falling out with the employer, and never went back for it.

I went and looked at it yesterday and the initial impression reflects the low mileage. There's hardly any rust on the engine and it still has a lot of original stickers on it in like new condition. The trans is still connected and it looks very clean too. I'm going to go back tomorrow to see if it spins by hand and maybe pull a valve cover. If it does I'll make an offer on it. It's covered in dust but unbelievably clean once it's wiped off. The carb even looks nice. I'm leery of anything sitting that long but it's been in a climate controlled environment the whole time. We shall see!

 

[G-Body_Vet]

...and the low oil pressure got to it.

What's the common cause of that? I've seen quite a few 403s for sale over the years that seem to have "ran great when pulled but had low oil pressure".

I'm guessing people are wiping out the main bearings.

 

[rccktmn2]

On just about all small and big block olds the common theory is the oil holes from the mains to the cam bearings are too large and they need to be resricted to keep more oil at the mains of the crankshaft. There are restrictor kits available to limit the oil flow to the cam bearings and keep the oil at the crank. At high rpm's most of the oil is pumped to the top of the engine away from the crank which results in oil starvation at the crank which results in burned/fried/melted/scorched crank bearings. The common olds block big or small will survive very well below 5-6000 rpm, anything above that and you will have some problems. The other theory is that the 403's are weak blocks because of the "windows" in the main webbing of the block, and that is why they make poor performance engines because of weak mains and poor oiling. I've had 2 of these engines and never had a problem, the pistons are huge and as long as your not going to extremes (500 hp and up) you should be fine.