Oldsmobile 403

[CamaroAdam73]

So how heavy is this engine compaired to a typicall SBC?
It feels like it's got a good bit more weight than my 350's do. Even our 406 for the late model seems lighter.

 

[CHRIS.O]

http://www.carnut.com/specs/engdim.html

That page has a bunch of weights for engines. I dunno how accurate it is though. I have always felt oldsmobiles were way heavier. They have to be. I have moved them around on the floor and they were so much hard to yank/pull/shove that a sbc. Anyway hope that page helps you.

 

[FE3X CLONE]

So how heavy is this engine compaired to a typicall SBC?
It feels like it's got a good bit more weight than my 350's do. Even our 406 for the late model seems lighter.

I don't know how much a typical SBC weighs as I've never messed with one but most all SBO engines are rated around 560lbs fully dressed. However the 403 does weight less than the typical earlier SBO engines. A bare block comes in around 170lbs where as an early 350 would be around 195lbs and a 455 is around 205lbs (block only).

A fully dressed BBO is around 605lbs. This is why it's not so critical to change out your front springs when going from a SBO to BBO. Put an aluminum intake on a 455 and your back down close to a stock SBO's weight.

 

[CamaroAdam73]

Well, there's big debate over the 403 being a SBo or BBO, based on deck height i call it being a SBO. And I've already got a nice new edelrbock aluminum intake, i couldn't believe the original intake weighed 60 pounds

 

[FE3X CLONE]

Well, there's big debate over the 403 being a SBo or BBO,

Big debate by who? There is NO debate, it's a small block, end of story.

For some the ignorant people out there think that the 400cid mark somehow dilenate's the switch from a small block to a big block when displacement actually has nothing to do with it.

Like you said, a 403 is a small block in that it has the same deck height as all other small block Olds engines. Same as the 260/307/330/350.

Small block Olds engine deck height = 9.33"
Big block Olds engine deck height = 10.625"

 

[CamaroAdam73]

Yeah that's pretty much what i go by. Plus The manufacturer (oldsmobile) says it's a small block, end of story. Beleive it or not, go talk to allot of people and you'll get mixed answers on what they claim it is.

Anyways, TWO NEW QUESTIONS for all you oldsmobile guros!

First, why was my 403 rated at 320/ftlb at 2200 RPM? There is no way the Torque starts dropping off at 2200 RPM.

Second! I already know the answer but want some other opinions, this engine being a 8:1 static compression (the original owner claims they swapped pistons but i think he's full of sh*t, also told me it was one of the "solid mains because it has the factory towing package" when in reality thats ****ing rare, and almost unheard of) Would running high octane (93+) have any benefits Versus the normal 87 grade?

 

[Likethat]

I have heard P.O.B and Caddy called mid blocks before. Out side of the 301 being a bit different I believe Olds of the 4 only has two "Block sizes being big and small". 8:1 would see no change in 93 octane.

 

[G-Body_Vet]

the original owner claims they swapped pistons but i think he's full of sh*t, also told me it was one of the "solid mains because it has the factory towing package" when in reality thats ****ing rare, and almost unheard of

Yeah, I think he was blowing smoke up your *ss. This is probably where he got that info: http://www.442.com/oldsfaq/ofe403.htm#E403 403CIDEngineDetail

"Main Bearing Webs
The main bearings are supported in/ connected to the block with webs of cast iron. Later motors, after 1976, including the 403's [most, anyhow] had not solid webs but webs with holes. Thus, there were essentially 3 fingers of cast iron holding each main bearing.

Good luck finding a Solid Main Web 403 motor. Rumor has it that some 403 blocks were made w/o holes in the webs- Solid Main Web 403's. Supposedly 403 solid main web blocks are found in the Pontiac Bonneville with the towing package, and in some 1979 Pontiac Trans Ams with a towing package."

 

[CamaroAdam73]

I won't hold my breathe. I guess i'll find out for sure when the day comes to rebuild this 403, which hopefully won't be for along time.

Anybody able to answer the factory power ratings question? If this Torque monster puts out 320 FTLB at 2200, and it doesn't drop off, i can't wait to see where the peak of the torque curve sits! My engine is only very mildly modified, edelbrock intake, headers, and a total revamp on the carb. So it should post almost stock numbers.

 

[CHRIS.O]

My LT1 in my formula puts out 320ftlbs at 2400 and it drops from there on. Not hard to believe really. Doesnt mean that at 3500 rpm it only has 200ftlbs of torque or anything like that, but yea it will go down hill from there. 403 has is an emission engine, junk heads, low compression. They make torque to pull large cars around.