Nozzle Check Valve Stihl Part Number

[SteveSr]

This jet is nla for a long time and was superseded to the one I mentioned above (4119 121 5400)

This may actually be the correct one if the original doesn't have a metering orifice in it.

 

[Vintage Engine Repairs]

Ha this is crazy confusing. I got the PN from another S3C carb in the ipl. I expect it to transfer across. Orifice size isn’t an issue because it’s metered by the H screw. Will report back when it arrives and let ya’ll know

 

[Vintage Engine Repairs]

This may be misleading since Mediacat doesn't go back far enough to list the C3A-S4 carb. However, It does show the following for carbs above S19:

...5402 - Valve Jet 0.60 Technote 33.1997
...5408 - Valve Jet 0.58
...5409 - Valve Jet 0.56 High Altitude

What is also interesting is that it would seem that these have an actual metering orifice in the jet itself. These carbs had primary flow through the valve jet with secondary flow through the "H" needle. This is the beginning of the limited adjustability carbs.

The C3A-S4C carb that is in my 034S has all of the "H" circuit through the needle and there is NO metering hole in the main nozzle. This may be why valve jets from some smaller carbs also fit the C3A-S4C. BTW, mine also seems to have a long oval welch plug instead of the triangular one shown.

I recon you’re spot on. The hole size of the current nozzel check valve is 1.6mm. If that was free flowing I wouldn’t get above 4000-5,000 rpm haha.
If I don’t have any luck, I could try swapping the check valve disk out and put it on my old nozzel check valve. Even just drill the hole in the nozzel valve larger if it’s too small. It’s not metering anything, just there to stop air coming back into the metering side.

 

[SteveSr]

I recon you’re spot on. The hole size of the current nozzel check valve is 1.6mm. If that was free flowing I wouldn’t get above 4000-5,000 rpm haha.
If I don’t have any luck, I could try swapping the check valve disk out and put it on my old nozzel check valve. Even just drill the hole in the nozzel valve larger if it’s too small. It’s not metering anything, just there to stop air coming back into the metering side.

I think that you are confused or don't have an S4C carb. The jet size is the metering hole on the BACK of the nozzle that is exposed to fuel in the metering chamber. Yours should have NO hole in this location. If so, NONE of the 3 choices that I listed will work in your application... unless you can solder the metering hole closed without damaging the check valve disc.

 

[SteveSr]

I recon you’re spot on. The hole size of the current nozzel check valve is 1.6mm. If that was free flowing I wouldn’t get above 4000-5,000 rpm haha.
If I don’t have any luck, I could try swapping the check valve disk out and put it on my old nozzel check valve. Even just drill the hole in the nozzel valve larger if it’s too small. It’s not metering anything, just there to stop air coming back into the metering side.

I think that you are confused about how a fully adjustable carb (S4C) works vs. one that is only partially adjustable within a limited range (the ones with the metered valve jets). We need to send you to one of @backhoelover remedial carb classes! Based on your earlier photo you need the previously mentioned Zama A007028 main nozzle assy. Good thing that it is still available as I may be needing one too!

 

[Vintage Engine Repairs]

right ordered 4119 121 5400 too. Let’s see if this one works.

 

[Vintage Engine Repairs]

DND and Harley, your PN is correct, thanks chaps. Steve, you’re right the 08 PN has a drilling