Here's my best quess on Carter Jet sizes:

I had found the flow rate of various carter jets (low, high; then computed the mean)

I then compared the mean flow rate to the flow rate of holley jet sizes to determine the holley equivalent size

The % column is was compared to my stock jet 120-263S

Unfortunately I can't find the source of the flow rates. It was a site that had a bunch of Carter spec sheets. Some of those sheets had flow rates. (I did find the spreadsheet I made a couple of years ago to get this data)



Number.......Low....High....Mean...............diameter.....Holley equivalent
120-265S....320.....326.....323....79.95%....0.0613........63
120-264S....337.....343.....340....84.16%....0.0629........64
120-268S....360.....366.....363....89.85%....0.0650........65.5
120-267S....380.....386.....383....94.80%....0.0668........66.5
120-263S....400.....408.....404....100.00%...0.0686........67.5
120-277S....417.....423.....420....103.96%...0.0699........68.5
120-293S....436.....444.....440....108.91%...0.0716........69.5


Don't forget that the jets are used with a metering rod...........

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Great info, thanks!
Does this mean one must also change metering rods when changing jets? That is, do smaller jets require smaller metering rods?

You can just change jets.

or

just change metering rods.

or

do both.


You subtract the area of the metering rod from the area of the jet to get the effective jet size.

Some setups work as

jet only, then jet + metering rod.


Others have a stepped rod and the different areas depend on the area of the steps..

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

You size the various areas you get with the metering rod/jet so that one size is for power another for cruise.

With multiple steps, you can have intermediate sizes too.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

So of the old AFB's came with 3 step meter rods. I would mine trying to get a hold of some to try in my new AVS.