2F carb venturi functionality question (1 Viewer)

[tpromano]

I've been browsing mud for a while to find an answer to this question, but it seems to be too specific to be able to look up.

I had a mechanic work on my carb a while back and I'm running into some bucking/fuel delivery issues so I started taking a look at my carb. Before the mechanic got my FJ60, the stock carb had the emulsifiers shown below in the first pic, and after I for the truck back, it had the emulsifiers shown in the second pic. I'm seeing a huge difference as one set of emulsifiers have holes in them and the other doesn't.
My air horn shown in the third pic clearly has holes that are supposed to meet with the holes in the first pic (I have one o-ring that I know was supposed to go there), but now they aren't meeting.
I'm thinking that the holes are to help atomize the fuel when needed, but now very curious as to what they are for. Anyone able to explain?
Thanks

 

[g-man]

the two venturi ( you call them emulsifiers) in the first image are USA, the others are NON USA. He probably pulled them from a NON USA carb and didn't know it. But why ??? What was wrong with your originals? The holes I imagine are vacuum passages. The FSM shows several images of the USA venturi with the o rings in place on top. And the NON USA just like your lower picture. I'd want to get my USA venturis back. They are chrome and brass colored. The chrome is the 1st and the brass is #2. they go to their perspective bores.

images of USA venturi with o ring on top:

Image of NON USA venturi w/out o ring:

 

[g-man]

I'd guess a decent rebuild kit would have the o-rings. Maybe someone can chime in that has a kit and can check.

 

[MDH33]

Maybe your mechanic swapped your stock carb for one of the made in China carbs? Kind of looks like it. Any more pics so we can see what you currently have?

 

[g-man]

Maybe your mechanic swapped your stock carb for one of the made in China carbs? Kind of looks like it. Any more pics so we can see what you currently have?

ewww, I think your right. Ugh. Lots of shiny cadmium coated stuff that wouldn't be there with a USA rebuilt carb. Hope the OP can get is original carb back.

 

[g-man]

Obviously the horn section is original and you can see some carbon on the linkage and even in the primary bore where the choke plate is. But the lower section looks totally like new non USA piece.

 

[g-man]

And other than the venturis, non usa carbs are jetted differently and don't have the same vacuum ports.

 

[2mbb]

Here is a cut-away view of the USA carburetor from the 2F engine manual. Those holes are little air bleeds maybe to get better emulsification or maybe to prevent some kind of siphoning. This detail is the same in the FSM for the non-usa carburetor.

 

[2mbb]

Checking the parts diagram, unfortunately this part (the main nozzles) were not identified as separate parts. however some non-USA spec carburetors seem to NOT have the air bleed hole. Below is the parts diagram for "General Countries" and the gaskets on top of the nozzles are missing, implying there is no air bleed hole. The USA diagram is shown at the bottom, with the gaskets:

 

[2mbb]

If the mechanic did a swap, that would be unfortunate. I think you might have difficulty passing California smog with different jets, etc. Especially if the vacuum ports are not all there. On the lower throttle body assemby there are four vacuum ports surrounding the idle mixture screw. You can see the tubing that connects tot he ports to the vacuum manifold in the USA schematic above.

 

[g-man]

I think the 1st image of the USA venturi are both #1 ...neither is brass and both have a #1 stamped on them. Maybe you need a #2.

 

[Spike Strip]

The holes into the Venturi work in conjunction with the HAC (High Altitude Compensation) valve and above 4000', bleed air into the carb to lean out the mix since at elevation, air is thin, so mix naturally runs too rich.

On the front (toward radiator) of the Air Horn on USA models, there are three ports. The outer two are the intake for those holes that are normally sealed with the little O-rings.

Yes, it looks like whoever rebuilt that carb mixed non-usa or aftermarket parts.

The ports with red caps on this Air Horn are the HAC circuit.

 

[tpromano]

the two venturi ( you call them emulsifiers) in the first image are USA, the others are NON USA. He probably pulled them from a NON USA carb and didn't know it. But why ??? What was wrong with your originals? The holes I imagine are vacuum passages. The FSM shows several images of the USA venturi with the o rings in place on top. And the NON USA just like your lower picture. I'd want to get my USA venturis back. They are chrome and brass colored. The chrome is the 1st and the brass is #2. they go to their perspective bores.

View attachment 2911825

images of USA venturi with o ring on top:
View attachment 2911826

Image of NON USA venturi w/out o ring:
View attachment 2911827

But why is the question!! No idea why the mechanic swapped the original venturis. Luckily he still had them lying around so I’ll be putting them back in shortly…

 

[tpromano]

Appreciate everyone’s input. These photos are grabbed from different posts on google images and mud. The mechanic left most of my USA carb as one, just seems like he swapped out some of the internals. This was all in an effort to get the FJ to pass smog.. which it did. But now it’s running like crap so trying to get back to normal.
It’s funny (kind of not because it’s not great work on the mechanics side), I found one of those orings (21659-38110) sitting on the secondary butterfly valve flap and couldn’t figure out where it came from. I happened to come across that carb exploded view and realized where it came from. Will be making moves to get the original venturis and orings back where they are supposed to be this weekend. Thanks for all the identification help.