BBOlds vs SBC
Thread Starter
Pro
Joined: Jan 2004
Posts: 565
Likes: 0
From: Toronto ON
BBOlds vs SBC
No, not a race, I'm just wondering.
Soundwise, a 350 Olds Rocket engine seems to be a little more "relaxed" at idle. I can't quite describe it. Although we're talking about the same idle speed, what could account for this difference? The Olds is carbureted. I'm not even sure if the Olds is a big block :bb
Anybody want to explain this phenomenon away?
Soundwise, a 350 Olds Rocket engine seems to be a little more "relaxed" at idle. I can't quite describe it. Although we're talking about the same idle speed, what could account for this difference? The Olds is carbureted. I'm not even sure if the Olds is a big block :bb
Anybody want to explain this phenomenon away?
Burning Brakes
Joined: Nov 2001
Posts: 1,189
Likes: 2
From: Austin TX
Re: BBOlds vs SBC (Vett-eight-nine)
A difference in cam and a difference in compression ratio would make
an engine sound different at idle. But the amount of ignition timing advance
at idle can make a big difference too. With only 6 or 8 degrees of advance
at idle speeds, and engine can sound like it's "hitting hard", even though
it's not under load, especially if it has a higher compression ratio and/or
bigger cam. Take that same engine and crank the advance at idle up
to 30 degrees, and the engine smooths out, the exhaust note gets alot
quieter, and it sounds like, well, that it's just "idling".
Dan
an engine sound different at idle. But the amount of ignition timing advance
at idle can make a big difference too. With only 6 or 8 degrees of advance
at idle speeds, and engine can sound like it's "hitting hard", even though
it's not under load, especially if it has a higher compression ratio and/or
bigger cam. Take that same engine and crank the advance at idle up
to 30 degrees, and the engine smooths out, the exhaust note gets alot
quieter, and it sounds like, well, that it's just "idling".
Dan
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: BBOlds vs SBC (Vett-eight-nine)
The olds was tuned for ease and quiet... the block was also a strange mid-block... not a small block, but not a big block, either.
That motor can be bored out and stroked up to 455 cubes! I think the deck height is different at that size, tho...
That motor can be bored out and stroked up to 455 cubes! I think the deck height is different at that size, tho...
Safety Car
Joined: Mar 2000
Posts: 3,581
Likes: 1
From: Springfield VA
Re: BBOlds vs SBC (bogus)
The original 350 Olds Rocket was made using a longer stroke and a smaller bore. It allowed the engine to rev slower, produce its torque a little higher up and to be able to cruise at higher speeds and lower rpms using the same tranny as the Chevy (TurboHydramatic 350).
It was developed to pull a 4000+ lb car around at 75-85mph all day long.
[Modified by 96LT1, 10:41 PM 4/27/2004]
It was developed to pull a 4000+ lb car around at 75-85mph all day long.
[Modified by 96LT1, 10:41 PM 4/27/2004]
Thread Starter
Pro
Joined: Jan 2004
Posts: 565
Likes: 0
From: Toronto ON
Re: BBOlds vs SBC (bogus)
Compression ratio is 8.5:1.
The stock cam was changed to an Edelbrock Performer with the matching intake. the carb was re-jetted.
What a difference.
I can't wait to get a g-tech on there to test it out. :D
The stock cam was changed to an Edelbrock Performer with the matching intake. the carb was re-jetted.
What a difference.
I can't wait to get a g-tech on there to test it out. :D
Burning Brakes
Joined: Apr 2000
Posts: 980
Likes: 2
From: Chandler AZ
Re: BBOlds vs SBC (Vett-eight-nine)
I'm not even sure if the Olds is a big block :bb
Anybody want to explain this phenomenon away?
Anybody want to explain this phenomenon away?
By the way, I have a 67 Toronado 425 in my 70 chevy pickup. It is in front of a 700R4 built tranny. It has no problem turning over 33x12.5x15 mud and snow tires until they boil. I guess I am kind of an Olds fan.
[Modified by VAHROOM, 10:34 PM 4/27/2004]
Instructor
Joined: Sep 2002
Posts: 175
Likes: 0
From: Oceanside CA
Re: BBOlds vs SBC (VAHROOM)
The 455's are a physically bigger engine. The manifold width is 2 inches wider than a 307-350-403 Olds. I can attest to this having owned a 72 442 with a 455. I still have a blown up piston from that engine. If you want to read more go to: ( Hit refresh after you first click it. seems when you first go there, the page doesn't appear. )
http://www.442.com/oldsfaq/ofeng.htm
http://www.442.com/oldsfaq/ofeng.htm
Burning Brakes
Joined: Apr 2000
Posts: 980
Likes: 2
From: Chandler AZ
Re: BBOlds vs SBC (sinc93)
It's kind of a weird thing. The BB's are wider due to the raised deck heigth. The heads from a SB will bolt to a BB and vice-versa. The intakes have to be a little wider due to the raised deck also.
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