AFB carb jets

Can anybody tell me the size jets needed in a AFB carb for a strong 1972 454?. about the size of what a 850 holly carb would have.

 

Remember in the Carter AFB, there are metering rods (step-up rods) which go through the primary jets.

A GREAT STARTING POINT IS THE ORIGINAL JETS AND RODS THAT CARTER PUT IN THE CARBURETOR WHEN CARTER BUILT THE CARBURETOR!

If you are going to compare the Carter jets to Holley, then you need to do some math.

Calculate the area of the Holley primary jet.

Calculate the area of the power step (the smallest step) on the step-up rod.

Add these two areas together. This is the area of the Carter jet that, with that particular step-up rod, would give approximately the same flow as the Holley. Now that you have the area, you can calculate the diameter needed. It isn't going to be exact, because the Holley and Carter will have different size air bleeds.

As the secondary jets do not have the rods, the diameter will be closer to that of the Holley.

AGAIN, best advice - BUILD IT STOCK FIRST, AND TUNE FROM THERE!

Jon.

 

I was freshening up the AFB on a friends '61 Buick and I noticed something very strange, it has no secondary jets.
I have never seen this before, it just has a small tube-like area in the back wall of the fuel bowl with a hole in the end. Very interesting.


Sent from my iPhone using The H.A.M.B. mobile app

 

You should probably read and save this: http://www.mymopar.com/downloads/carterafbtuning.pdf

 

Not that difficult to figure out...
http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf
Check page 9. Find the size carburetor you have, go from there. May not be "perfect", but a damn good starting point. Also, the Carter vs. Edelbrock part numbers are different, but jet sizes are mentioned.

Also, like has been noted, you have metering rods AND springs to tune with, not JUST jets.

Mike

 

My son tuned the AFB the 308 Hudson. He used the meter using O2 sensors. Edelbrock parts interchange. Like Mike VV said, it takes a combo of springs, rods and jets.

 

Be VERY CAREFUL when trying to do this interchange.

Carter alone used three different jet TYPES, and 19 different rod TYPES in the AFB, so not even all Carter parts interchange CORRECTLY, let alone the clone parts.

Oh, and the "missing" Buick secondary jets - try looking under the secondary venturi cluster after you remove it.

Jon.

 

Well, well, those Carter engineers were pretty darn sneaky weren't they? I wonder, why the change? Thanks Jon.