SB to BB?
10-21-2017, 02:14 PM
#1
Drifting
Thread Starter
SB to BB?
Like many I spend time thinking about what can be done to make my 74 better/faster.
At some point I think I will have to move up to a BB. A SB has to be pushed too hard.
My question: Is a modern 502 any more trouble than the old 454 to swap into my 74 w/SB?
I know mounts and brackets have to be changed. Would it be the same as the old BB?
The idea of having over 500 hp on tap is appealing!
TIA
R
At some point I think I will have to move up to a BB. A SB has to be pushed too hard.
My question: Is a modern 502 any more trouble than the old 454 to swap into my 74 w/SB?
I know mounts and brackets have to be changed. Would it be the same as the old BB?
The idea of having over 500 hp on tap is appealing!
TIA
R
10-21-2017, 03:43 PM
#2
Safety Car
No difference between a 396-502 (or 540 for that matter) dimensionally speaking. You will need to track down brackets, pulleys exhaust manifolds/headers. Distributor, bellhousing, motor mounts, starter are all transferable from a SB to BB.
10-21-2017, 03:43 PM
#3
Pro
Member Since: Sep 2017
Location: Modesto California
Posts: 516
Likes: 0
Received 71 Likes
on
71 Posts
Like many I spend time thinking about what can be done to make my 74 better/faster.
At some point I think I will have to move up to a BB. A SB has to be pushed too hard.
My question: Is a modern 502 any more trouble than the old 454 to swap into my 74 w/SB?
I know mounts and brackets have to be changed. Would it be the same as the old BB?
The idea of having over 500 hp on tap is appealing!
TIA
R
At some point I think I will have to move up to a BB. A SB has to be pushed too hard.
My question: Is a modern 502 any more trouble than the old 454 to swap into my 74 w/SB?
I know mounts and brackets have to be changed. Would it be the same as the old BB?
The idea of having over 500 hp on tap is appealing!
TIA
R
It'll drop right in to any of the C3's. The only problem could be the height as a big block will require a big block hood and if it's a big block with a high rise intake it'll require an L-88 style of hood. As the big blocks were an option all of the parts are available to make the conversion. They are tire smokers!
10-21-2017, 04:08 PM
#5
Instructor
It'll drop right in to any of the C3's. The only problem could be the height as a big block will require a big block hood and if it's a big block with a high rise intake it'll require an L-88 style of hood. As the big blocks were an option all of the parts are available to make the conversion. They are tire smokers!
10-21-2017, 04:21 PM
#6
Team Owner
Member Since: Oct 2004
Location: altered state
Posts: 81,242
Received 3,043 Likes
on
2,602 Posts
St. Jude Donor '05
500ci trumps a sb lsx 
Nothing like part throttling yourself past traffic without a sweat. Lots of fun, maybe someday. As you said dont have to push em hard, even one that pulls well to 6k is plenty to get in trouble.
This one had a 460 on the bottle most figured it was just another 5.0 til the light turned green
Nothing like part throttling yourself past traffic without a sweat. Lots of fun, maybe someday. As you said dont have to push em hard, even one that pulls well to 6k is plenty to get in trouble.
This one had a 460 on the bottle most figured it was just another 5.0 til the light turned green
10-21-2017, 04:25 PM
#8
Drifting
Thread Starter
It'll drop right in to any of the C3's. The only problem could be the height as a big block will require a big block hood and if it's a big block with a high rise intake it'll require an L-88 style of hood. As the big blocks were an option all of the parts are available to make the conversion. They are tire smokers!
An LS motor is being considered. I'm concerned about the amount of fabrication needed?
I'm not set up for that and would have to pay someone else to do it!
I am keeping my options open, but a 502 w/6 speed would be a great
Grand Tourer!
R
10-21-2017, 04:25 PM
#9
Aren't the front springs different from SB to BB?
10-21-2017, 04:26 PM
#10
I did a 502 in my Nova. I had a Mark IV BBC 427 in it previously. Everything from the 427 transferred over. One thing to note; I believe all Gen VI BBC's do not have provisions for a mechanical fuel pump. Such was the case on mine. So, an electric fuel pump of some sort is required. I'm very pleased with the 509 (502 + .030), but would've preferred a mechanical pump.
10-21-2017, 04:34 PM
#11
Drifting
Thread Starter
New Driveline?
For the moment I'm trying to upgrade in stages.
I understand that big power requires special and expensive parts.
I'm not ready to join that club just yet! lol
10-21-2017, 06:35 PM
#12
Le Mans Master
As far as the driveline-- a good hot SB will pop it just as well as a BB will- just maybe not as quick. Face facts- if it hooks up really well with either one, something will break eventually.
10-21-2017, 09:33 PM
#13
Team Owner
Member Since: Oct 2004
Location: altered state
Posts: 81,242
Received 3,043 Likes
on
2,602 Posts
St. Jude Donor '05
Street tires, good Ujoints should live awhile. You can drive a car somewhat hard and not abuse it.
10-21-2017, 09:59 PM
#14
Le Mans Master
Ol' Red still has the factory installed u-joints and rear end. And it's had 4 different BB's, each one meaner than the last. Rear is coming out this winter. There's too much slop in the stub axles.
10-21-2017, 10:17 PM
#15
Pro
Member Since: Sep 2017
Location: Modesto California
Posts: 516
Likes: 0
Received 71 Likes
on
71 Posts
The first thing you'll notice is it'll handle like a Greyhound bus when going around corners; the result of an additional 200+ pounds AND you'll need the stronger big block front springs because of the additional weight.
10-22-2017, 12:33 AM
#16
Drifting
Thread Starter
Perhaps they were wrong?
No matter how many Alm parts on BB. It will always be a few more than SB.
I believe an LS motor is #50lbs less? I could be wrong.
I'm thinking Old School Grand Touring. High speed cruising in comfort.
R
10-22-2017, 07:41 AM
#17
Le Mans Master
A complete cast iron BB will weigh about 650-700 lbs versus a complete cast iron SBC at 450-500 lbs...200 lbs is indeed the difference in weights....its a lot, especially towards the front nose of the car. Of course, you can add aluminum heads, flywheel, intake, radiators, water pump, etc to reduce the weight of either by much as well.The other issue with the BB is its not just the added weight BUT where the weight is...The BBC in a C3 due to its size is not only much heavier but dimensionally sits slightly forward of the front axle mid line and much higher in the engine bay which adversely effects weight bias front to rear and center of gravity for handling. The typical cast iron BBC C3 back in the day had front to rear weight distribution of:
BBC C3 weight distribution:
Front 52-54%/Rear 46-48% some numbers published are as high as 56% front:44% rear
SBC C3 weigh distribution:
Front 47-50%/Rear 53%-50%
You ideally would want a slight weight bias to the rear like in the C3 SBC for the best handling and Duntov preferred the SBC C3/C2's for this very reason!
With all that stated, why would you want a BBC in your C3 today, when any number of SBC configurations with roller cams, modern aluminum high flow heads like AFR and others along with 10:1 compression on mid grade gas can easily give you the power of a BBC without the weight penalty on the street. You can easily take your 350 block, turn it into a moderate 383 with 525-550 Gross HP/500+ TQ that will make great torque off idle, have monster mid range torque and still will scream to 6,000 RPM! You can build the motor to maximize mid range torque with a moderate duration cam and the correct CC head runners......Think about it!
You will be safe with the stock drivetrain as long as you don't abuse it with 450-500 Gross HP. With my built 355 L-82 4 speed with 3.70 gears, I have avoided clutch dropping at moderate revs from idle and generally roll into the throttle while moving...OEM tranny, rear, and u joints!
Last edited by jb78L-82; 10-22-2017 at 07:47 AM.
10-22-2017, 08:21 AM
#18
Le Mans Master
Member Since: Mar 2001
Location: Watkinsville, GA and Glen Cove, NY
Posts: 5,788
Received 854 Likes
on
625 Posts
A complete cast iron BB will weigh about 650-700 lbs versus a complete cast iron SBC at 450-500 lbs...200 lbs is indeed the difference in weights....its a lot, especially towards the front nose of the car. Of course, you can add aluminum heads, flywheel, intake, radiators, water pump, etc to reduce the weight of either by much as well.The other issue with the BB is its not just the added weight BUT where the weight is...The BBC in a C3 due to its size is not only much heavier but dimensionally sits slightly forward of the front axle mid line and much higher in the engine bay which adversely effects weight bias front to rear and center of gravity for handling. The typical cast iron BBC C3 back in the day had front to rear weight distribution of:
BBC C3 weight distribution:
Front 52-54%/Rear 46-48% some numbers published are as high as 56% front:44% rear
SBC C3 weigh distribution:
Front 47-50%/Rear 53%-50%
You ideally would want a slight weight bias to the rear like in the C3 SBC for the best handling and Duntov preferred the SBC C3/C2's for this very reason!
With all that stated, why would you want a BBC in your C3 today, when any number of SBC configurations with roller cams, modern aluminum high flow heads like AFR and others along with 10:1 compression on mid grade gas can easily give you the power of a BBC without the weight penalty on the street. You can easily take your 350 block, turn it into a moderate 383 with 525-550 Gross HP/500+ TQ that will make great torque off idle, have monster mid range torque and still will scream to 6,000 RPM! You can build the motor to maximize mid range torque with a moderate duration cam and the correct CC head runners......Think about it!
You will be safe with the stock drivetrain as long as you don't abuse it with 450-500 Gross HP. With my built 355 L-82 4 speed with 3.70 gears, I have avoided clutch dropping at moderate revs from idle and generally roll into the throttle while moving...OEM tranny, rear, and u joints!
Can’t argue with anything said but no one can argue the wow factor when you pop the hood and see that Rat in there. Never seen that reaction to an LS. Big block any day for me.
The following users liked this post:
73racevette (10-23-2017)
10-22-2017, 08:49 AM
#19
A complete cast iron BB will weigh about 650-700 lbs versus a complete cast iron SBC at 450-500 lbs...200 lbs is indeed the difference in weights....its a lot, especially towards the front nose of the car. Of course, you can add aluminum heads, flywheel, intake, radiators, water pump, etc to reduce the weight of either by much as well.The other issue with the BB is its not just the added weight BUT where the weight is...The BBC in a C3 due to its size is not only much heavier but dimensionally sits slightly forward of the front axle mid line and much higher in the engine bay which adversely effects weight bias front to rear and center of gravity for handling. The typical cast iron BBC C3 back in the day had front to rear weight distribution of:
BBC C3 weight distribution:
Front 52-54%/Rear 46-48% some numbers published are as high as 56% front:44% rear
SBC C3 weigh distribution:
Front 47-50%/Rear 53%-50%
You ideally would want a slight weight bias to the rear like in the C3 SBC for the best handling and Duntov preferred the SBC C3/C2's for this very reason!
With all that stated, why would you want a BBC in your C3 today, when any number of SBC configurations with roller cams, modern aluminum high flow heads like AFR and others along with 10:1 compression on mid grade gas can easily give you the power of a BBC without the weight penalty on the street. You can easily take your 350 block, turn it into a moderate 383 with 525-550 Gross HP/500+ TQ that will make great torque off idle, have monster mid range torque and still will scream to 6,000 RPM! You can build the motor to maximize mid range torque with a moderate duration cam and the correct CC head runners......Think about it!
You will be safe with the stock drivetrain as long as you don't abuse it with 450-500 Gross HP. With my built 355 L-82 4 speed with 3.70 gears, I have avoided clutch dropping at moderate revs from idle and generally roll into the throttle while moving...OEM tranny, rear, and u joints!
The following users liked this post:
73racevette (10-23-2017)