Carb size for mild 440

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cpearce

cpearce

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Good morning everyone,

I am a little out of my element here.

A friend of mine has a 67 Satellite with a motorhome 440. The engine is stock internally with the exception of a Hughes Whiplash cam, performer intake manifold. Car has 3.23 gears, tall rear tires, and stock exhaust manifolds. The car is used as a driver, road trip machine. The owner is looking at putting an new Edelbrock AVS2 carb on it. Although it is a 440 cubic inch engine I was thinking perhaps a 650 might fit the bill. I do not want to steer him in the wrong direction, am I wrong, does he need an 800? Ultimate performance is not the idea here, drivability and utility are key. Thanks guys.
 
I would go with the AVS 1906 650 because it is a spread bore . If it was a modified 440 I would go the 800.
 
I think Cpearce is on fhe right track with the 650 for this application . Its a street motor and will never be a high rpm performer in current state. Just maximize the bottom end torque.
I run an 800 version on my 360 but its build is different (portsd heads , headers , bigger cam etc) and sees higher rpms.
 
mbaird said:
I would go with the AVS 1906 650 because it is a spread bore.
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Sorry my brother but this is incorrect. Yes! Even though the primary and secondary throttle plates show a difference in sizes, this is still not considered a spread bore carb.

The TQ & QJ are spread bore carbs. There, the difference is obvious.
 
750/800 spread bore. Great fuel economy & go power. Thermoquad's work great if it's a good used one or a properly rebuilt unit. You really need the choke and it properly set up. In the long run you might be better off with a holly spread bore with a electric choke.
 
cpearce said:
Good morning everyone,

I am a little out of my element here.

A friend of mine has a 67 Satellite with a motorhome 440. The engine is stock internally with the exception of a Hughes Whiplash cam, performer intake manifold. Car has 3.23 gears, tall rear tires, and stock exhaust manifolds. The car is used as a driver, road trip machine. The owner is looking at putting an new Edelbrock AVS2 carb on it. Although it is a 440 cubic inch engine I was thinking perhaps a 650 might fit the bill. I do not want to steer him in the wrong direction, am I wrong, does he need an 800? Ultimate performance is not the idea here, drivability and utility are key. Thanks guys.
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While the 440 could most probably & happily use the 750, there isn’t a whole lot of power gain or rpm gain. The one reason I would move to the 750 is if he upgraded the engine.

History - An old friend of mine had a ‘66 Imperial w/a 440. The carb was a small diameter inlet AFB that also had no secondary air door above the throttle blades.
This carb is a 600 cfm unit. It never bogged or stumbled. Even when you slammed the go pedal. The secondary side would open up and just gobble down the air and fuel and the car would just GO!

If your bud wants a 90+% cruiser, I’d use the 600/650.
 
LO23M8B said:
750/800 spread bore. Great fuel economy & go power. Thermoquad's work great if it's a good used one or a properly rebuilt unit. You really need the choke and it properly set up. In the long run you might be better off with a holly spread bore with a electric choke.
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I have run the small primary TQ on a (lame) ‘78 - 400 B engine. I suggest a move to the larger primary TQ!
Well well worth it in a big way!
 
rumblefish360 said:
While the 440 could most probably & happily use the 750, there isn’t a whole lot of power gain or rpm gain. The one reason I would move to the 750 is if he upgraded the engine.

History - An old friend of mine had a ‘66 Imperial w/a 440. The carb was a small diameter inlet AFB that also had no secondary air door above the throttle blades.
This carb is a 600 cfm unit. It never bogged or stumbled. Even when you slammed the go pedal. The secondary side would open up and just gobble down the air and fuel and the car would just GO!

If your bud wants a 90+% cruiser, I’d use the 600/650.
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This was my thinking, the car is never really to the floor. Driveability is the program here, I know the thumper cam isn't really the ideal choice here, he had to have the choppy idle. Lol
 
Take a look at the newer street Demon.
I have great luck with the 625 on street driven small blocks, throttle response is excellent.
They also sell a 750 version which should work good on a 440.
 
cpearce said:
This was my thinking, the car is never really to the floor. Driveability is the program here, I know the thumper cam isn't really the ideal choice here, he had to have the choppy idle. Lol
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Oh yeah I gotcha! If it’s a complete and total cruiser, the 600 will be fine. It’ll Have plenty of power to get on the highway when the four barrels open up. Also, excellent throttle response.

The 750, will offer a bit more power under all conditions. But! If you don’t get that carbureted tune just right it will be a little sluggish on the takeoff.

With a Carter Square bore carburetor, I prefer to undersize just a little bit. Even more so when the gears are below 391.
 
650 AVS2.

86CDC353-2F38-46C9-AC6F-340B4836AA69.jpeg
 
rumblefish360 said:
Sorry my brother but this is incorrect. Yes! Even though the primary and secondary throttle plates show a difference in sizes, this is still not considered a spread bore carb.

The TQ & QJ are spread bore carbs. There, the difference is obvious.
Click to expand...

rumblefish360 said:
Oh yeah I gotcha! If it’s a complete and total cruiser, the 600 will be fine. It’ll Have plenty of power to get on the highway when the four barrels open up. Also, excellent throttle response.

The 750, will offer a bit more power under all conditions. But! If you don’t get that carbureted tune just right it will be a little sluggish on the takeoff.

With a Carter Square bore carburetor, I prefer to undersize just a little bit. Even more so when the gears are below 391.
Click to expand...

In keeping with our recent trend I respond ....

Rumblefish you ignorant slut !
Isnt that what I just said ?
And what constitutes a spread bore if it's not the venturis being of different size ?

You youngens may not understand my opening volley ...lol
 
I guess 440's were over carbureted from the factory. :lol:
carry on
 
It's listed by Edelbrock as a square bore, even though they have larger secondary throttle plates. I think their reasoning is that the carburetor will bolt onto a square bore manifold without requiring an adapter for throttle blade clearance.
 
Garrett Ellison said:
It's listed by Edelbrock as a square bore, even though they have larger secondary throttle plates. I think their reasoning is that the carburetor will bolt onto a square bore manifold without requiring an adapter for throttle blade clearance.
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So its just a square bolt pattern like the Holley . It is a spread bore venturi system though .

I have a 78 Dodge C-Class with a 440 and it has a holley 600 spreadbore QJ replacement carb on it . Runs as good as it can considering the comp ratio , cam and weight . Dont think a bigger carb will make a difference . Its a runner up to 3k..lol Then it just runs out of everything else.
 
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