AFB 3461S Jets and Rods

[Joel T.]

Hi Guys;

Still working on that vintage AFB as a backup for my 1963 3461S (Which will get sent out for a professional rebuild).. The rebuilding kits do not include jets or metering rods... I found them online but need to know what size metering rods I need... I believe the jets are .104 primary and .068 secondary.

I run a Competition Cams stick which is a little hotter than the stock 340 unit.

Thanks!

Joel

[William C.]

Re: AFB 3461S Jets and Rods

the 3461 OEM specs are primary jet .104 dia-P/N 120-161, metering rod is P/N 16-205 Secondary Jet is .070
p/n120-222

Hope this is what you need...

[Duke W.]

Re: AFB 3461S Jets and Rods

Last time I looked (but it's been awhile) Federal Mogul still offers a limited selection of vintage AFB jets and rods, and I think the parts that Edelbrock offers for their AFB clones will also work.

The '63 Shop Manual lists the 3461S jets as .104/.0689 with .060/.069 rods.

Overall this jetting is fairly rich and should work okay with a bit more cam. Later AFBs (372xxx) were a little leaner, but only used on the 327/300, so the jetting was more specific to that configuration rather than a compromise that would work on both 340 and 300 HP engines.

Higher overlap cams usually need bigger idle and cruise jetting, due to the effect of exhaust gas dilution on the fresh charge at idle and low speed/load.

Duke

[Joel T.]

Re: AFB 3461S Jets and Rods

Last time I looked (but it's been awhile) Federal Mogul still offers a limited selection of vintage AFB jets and rods, and I think the parts that Edelbrock offers for their AFB clones will also work.

The '63 Shop Manual lists the 3461S jets as .104/.0689 with .060/.069 rods.

Overall this jetting is fairly rich and should work okay with a bit more cam. Later AFBs (372xxx) were a little leaner, but only used on the 327/300, so the jetting was more specific to that configuration rather than a compromise that would work on both 340 and 300 HP engines.

Higher overlap cams usually need bigger idle and cruise jetting, due to the effect of exhaust gas dilution on the fresh charge at idle and low speed/load.

Duke

Bill/Duke;

Thanks guys, this is exactly what I was looking for...!

Joel

[Stuart F.]

Re: AFB 3461S Jets and Rods

In the FWIW department, those of us with 63's who have had our 3461S's stolen or worn out have had to struggle along with replacement 3721S (A & B)'s. It takes awhile to sort them out for our L-76's, but it can be done. One item overlooked which is critical (specially for tall final gearing, i.e. 3.36 or 3.08) is the pump nozzle (squirters). The 3721's used a #264 which has .0265" nozzles, while the 3461S uses #284 with .028" nozzles. You can find a #284 in some 3720S's (automatics) as I did. That, combined with a B28 VAC, helps with low speed stumble and hesitation a great deal.

Stu Fox

[Joel T.]

Re: AFB 3461S Jets and Rods

Hi Stew;

I actually found a 3461S from a local rebuilder and have had that unit on the car for a number of years now... It has a couple of issues so I plan on sending off to one of the rebuilders which this board recommends from time to time...

The unit which I am working with is an old 3721S which based upon what I can see has been "modified" for some sort of performance use... the primary jets look to be .120's and the secondaries I cannot really make out. In any event, they need to be history. I have no idea what rods are in there..

I appreciate the suggestion on the squirters.. I will check to see what size they are... hopefully I will get lucky.. the real problem is you cannot readily find this stuff..

I was also toying with the idea of putting a new Edelbrock on there for the interim but figured I would try this route first... it's more fun!

Be well;

Joel

[Stuart F.]

Re: AFB 3461S Jets and Rods

Joel;

I have a set of fine number drills that I use more for measuring of jets, pump nozzles and air bleeds, etc. I have been known to drill a jet now and then with them, but only as a last resort. It's also helpful to have a good mic as well, specially for our old eyes. I can't for the life of me read those little numbers on the jets or metering rods any more - even with a magnifying glass and lots of light.

You will also find a variety of venturi clusters were used in the 3720/3721 series that have different air bleeds and fixed jet tubes, but my understanding of carburetion theory limits my ability to figure an advantage one way or another on paper, so I tend to resort to the "bigger is better" back yard method.

I'm currently totally "blue printing" one old 3720SA just for fun including polishing the clusters, t******* the air valve weights, etc. I am changing the choke housing to one from a unit I picked up from a garage sale that has the hot air tube inlet on the housing rather than the phenolic cover in order to use an electric choke in place of the cover while maintaining the hot air bleed.

Stu Fox

[Stuart F.]

Re: AFB 3461S Jets and Rods

Gosh! what could be wrong or not P.C. about the word "T*******"? Guess I'm out of touch with the "new speak".

Stu Fox

[Stuart F.]

Re: AFB 3461S Jets and Rods

Oh Kat! how about grinding or cutting then?

Stu fox

[John H.]

Re: AFB 3461S Jets and Rods

Gosh! what could be wrong or not P.C. about the word "T*******"? Guess I'm out of touch with the "new speak".

Stu Fox

Stu -

The censor robot doesn't like the word "r i m m i n g".

[Stuart F.]

Re: AFB 3461S Jets and Rods

Thanks John. I'll try to remember that. What were we talking about now?

Stu Fox