carter avs/afb parts compatibility

[tparker]

Hi all,

I'm rebuilding my carter avs (4933). I picked it up for about $100 from Tony's. It is in Ok shape but REALLY need to be cleaned very well. Anyways, looking at replacement parts is a bit confusing and looking for some insights. It looks like a lot of sites have jets and rods listed for AFB Carbs. I ended up buying a kit, but I thought I'd ask.

Also, apparently some (all?) AVS carbs have 2 different types of jets. One is taller and one is shorter. Does this matter when getting replacements? I didn't notice a distinction when ordering. If not, why the different heights?

Thanks
Tom

[Chryco Psycho]

Talk to Scott Harms . He should have more info on specific differences .

[tparker]

OK. Is he a member? I'm bad with knowing members names.

Thanks
Tom

[Chryco Psycho]

Yes he is a member
@ScottSmith_Harms

[tparker]

So this is what I found out in case it helps someone else.

The metering rods for AVS are 3 step versions while the ABS are two step. The 3 step are a bit longer and help with the transition from 'idle' to wide open. Or something similar. I've also heard some claim it was due to various regulations. But with the AVS coming out in '68 I would be skeptical if that was the exact reason. Remember we had dual carbs and six packs on 426 and 440s. LOL. But maybe. Anyways, AVS carbs seemed to have suffered from the law of supply and demand. The demand isn't there and rods and jets aren't readily available anymore. What people seem to be doing is using AFB rods and jets. Eddlebrock carbs are based on the AFB and their rods and jets are compatible. BUT AVS primary jets are taller to account for AVS's 3 stage jets. In order to use the AFB jets and rods the cap needs to be changed to be the flat style instead of the domed one. Some people fill the dome up with epoxy so its flat. This is because the two step rods are shorter.

I probably got some details incorrect, but hopefully this will help.

Another thing, the jet markings as I understand it are decoded as following:
489 = 0.189
398= 0.098
The 4 translates to a 1 and the 3 to a 0. Or 4 > 0.100 and 3 < 0.100. I'm curious why they didn't just print 0 or 1. So there is probably something else to this numbering scheme.

I have seen a few people suggest the numbers are related to the short vs tall jet or primary/secondary jet.

Hopefully this is helpful and hopefully people will chime in with corrections or additional info