Intake manifold for Carter AFB for 1965 Impala with 409cui

[Gert Frost]

Hello,

 

can anyone clarify if there is any problem with using either of the manifolds 3814678 or 3844463 with the Carter AFB?

 

348-409.com writes this, but I’m unsure how to interpret it:

 

”Intake# 3844463 

Carb used: 4 bbl Carter AFB 
Year used: 1965 
Model: Passenger car 
Engine: 409 
Horsepower: 400 
Notes: This intake was used on all early 1963 400hp engines with the power brake option only. All early non power brake cars recieved #3814678 intake. Im mid year of '63, production swithched over and used this intake for all 400hp 409 application up to the end in 1965. ”

 

thanks

[joe_padavano]

Both are square bore intakes, so an AFB will bolt up in either case.

 

[Max4Me]

GertFrost

I’m not an expert here, but their statement is confusing to me. Their statement that in mid-‘63 all 409s used this manifold. Does “this” reference the antecedent “3814678” or the “3844463” in their description? But, it appears the 3844463 has a port added in the back, presumably for a vacuum line for the power brakes. If you have them you want to use this one.

[rocketraider]

Granted I'm unfamiliar with the Chevrolet W engine, but the big opening for 1-4-6-7 cylinder ports plane strikes me as unusual. Anyone know the engineering reason behind that?

[carbking]

Gert - having now seen the two manifolds, I believe my guess in our email conversation is correct.

 

Note that the top manifols has a vacuum port, ostensibly for a vacuum source for power brakes, thus being used on cars with power brakes.

 

The second manifold does not have the port drilled/tapped; and the vacuum source for power brakes probably was a port in the center rear of the carburetor, thus the manifold became "universal" and reduced redundant part inventory.

 

Jon.

[Gert Frost]

1 minute ago, carbking said:

Gert - having now seen the two manifolds, I believe my guess in our email conversation is correct.

 

Note that the top manifols has a vacuum port, ostensibly for a vacuum source for power brakes, thus being used on cars with power brakes.

 

The second manifold does not have the port drilled/tapped; and the vacuum source for power brakes probably was a port in the center rear of the carburetor, thus the manifold became "universal" and reduced redundant part inventory.

 

Jon.

Hello Jon,

 

that makes a lot of sense - I believe you’re completely right.. 👍

 

Does the Carter 3783s have this vacuum-port?

[carbking]

I think so, you will know shortly

 

Jon

[Gert Frost]

2 hours ago, Mark I said:

I’m a bit confused reading your posts on your 409. Do you know if you have a 340 hp or 400 hp? The cylinder heads and intake manifolds are different. There were 742 400 hp 409 65s made. All were manual transmission only. The 340 hp was available with a Powerglide.

How about some pictures?

Hello Mark,

 

Thanks for your question - the answer is - "it's complicated"..  or maybe not really.

 

My car is a 1965 Impala SS. It was born a 6 cylinder with powerglide, but somewhere along the way someone has put a 340hp 409cui in it, and fitted with an Edelbrock carburetor, HEI distributor, and a TH700R4.

 

I order to get the car approved "by the book" in Denmark, I have to configure the engine in such a way, that it resembles something that Chevrolet has described in its documentation.

 

The straight forward method is to get a Rochester 4GC low silhouette, that fits my engine and manifold - but it is rare. I'm in the process of trying to find this, this would make my car a bit more "original" - even though it really is'nt anyway (original, that is).

 

Another way is to get a Carter 3783s, which in Chevrolet papers replaces the 3499, which in turn is clearly documented by Chevrolet for the 409. The amount of HP is not important in this approval-process. The Carter is easier to find, but then I learned that it needed another manifold - I'm new to Chevrolet, so my knowledge builds for every obstacle I encounter.. 🙂  When I found what type of manifold, I learned that the cylinder head is also different.  I guess that the manifold is within reach, but I doubt that I will replace the cylinder heads any time soon, so I now wonder if the Carter 3783s with the appropriate manifold will be able to run on my 340hp engine and 340hp cylinder heads. I can see that the intake valve is smaller (2.06) on my as opposed to the 400hp (2.19).

 

I just need the car to run and respect the emission- and noise-limits in order to get approved. Once approved, I have all the time in the world to get it to run properly in the configuration I want.

 

I hope this answers your question.

 

kind regards

Edited September 11, 2022 by Gert Frost (see edit history)