Factory Carb Size

[monte0185]

Anyone know the factory carb size on an 86 Chevy dually with a BBC 454? Im pretty sure its a 750 but im debating on new airgap intake and carb since the edelbrock on it needs rebuilt anyway. Here is what I was thinking or should i just go back to a summit quadrajunk so all my stock stuff will still fit since all my vacuum lines are still hooked up and only thing not hooked up af far as i can tell is the overflow from the carb to the charcoal canister.

http://www.summitracing.com/parts/cmb-03-0224/overview/

[Keith Seymore]

I checked my factory information and while it lists carburetor type, venturi size and choke controls it does not specify a cfm rating.

K

http://www.gmheritagecenter.com/docs...olet-Truck.pdf

[monte0185]

I just wonder if maybe a 750 is a bit overkill for an 80s stock 454??

[walkerb]

750 is what I'm planning on using for my "much big than stock" 454. In my opinion 750 is a little to big for stock.

[oldcane]

Isn't it an 800cfm q-jet from the factory?

As for after market what I use is 600 up to 325hp or so and 650cfm (thunder) up to 400. Anything in the 400hp range I use a 750. I've never had anything over that so don't know where you'd want an 850 or 1050.

[monte0185]

Originally Posted by oldcane

Isn't it an 800cfm q-jet from the factory?

As for after market what I use is 600 up to 325hp or so and 650cfm (thunder) up to 400. Anything in the 400hp range I use a 750. I've never had anything over that so don't know where you'd want an 850 or 1050.

I do pretty much the same thing thats why it baffled me when all i seen was 750's when i put in my truck info on summit. Love the intake and carb combo but 750 i think is a bit of a stretch.

[oldcane]

Well, remember, it's usually just a 2-barrel for the average joe.....unless you drive like my wife. Then turns into an industrial water hose.

[monte0185]

Originally Posted by oldcane

Well, remember, it's usually just a 2-barrel for the average joe.....unless you drive like my wife. Then turns into an industrial water hose.

Mines the complete opposite she drives like shes on thorazine unless shes headed out of town on vacation then she puts new meaning to drive it like ya stole it.

[ray_mcavoy]

Originally Posted by monte0185

... all i seen was 750's when i put in my truck info on summit. Love the intake and carb combo but 750 i think is a bit of a stretch.

The CFM rating isn't exactly an apples to apples comparison when you're comparing Quadrajets to most other carburetors.

The Q-Jet's secondary air doors only open as far as needed to meet the engine's airflow demands. Combined with their relatively small primary venturis, that allows a 750 CFM Q-Jet to be used in applications where most other types of 750 CFM carbs would be too large and suffer from driveability issues.

[king-918]

Originally Posted by monte0185

Anyone know the factory carb size on an 86 Chevy dually with a BBC 454? Im pretty sure its a 750 but im debating on new airgap intake and carb since the edelbrock on it needs rebuilt anyway. Here is what I was thinking or should i just go back to a summit quadrajunk so all my stock stuff will still fit since all my vacuum lines are still hooked up and only thing not hooked up af far as i can tell is the overflow from the carb to the charcoal canister.

http://www.summitracing.com/parts/cmb-03-0224/overview/

using a 750 will work probably not the most efficient but it will start,drive,and kill you wallet fine. I had 1407 edelbrock on my stock 455 78 monte

[donut]

I believe mine is an 800 cfm.

Originally Posted by ray_mcavoy

The CFM rating isn't exactly an apples to apples comparison when you're comparing Quadrajets to most other carburetors.

The Q-Jet's secondary air doors only open as far as needed to meet the engine's airflow demands. Combined with their relatively small primary venturis, that allows a 750 CFM Q-Jet to be used in applications where most other types of 750 CFM carbs would be too large and suffer from driveability issues.

As far as the q-jet, they could be found on v-6's also. Very versatile.

[monte0185]

I finally decided to just stick with the edelbrock thats on there. Pretty sure its a 600 but I will know for sure when i rebuild it. Truck sat up for a number of years so its dumping fuel into the primaries. I also bought me a decent K&N 6" tell air cleaner and a few other goodies while i was at it so hopefull shell be running tip top shortly.