Zenith 281F questions...

[R4-Bob-F6]

Good-day all. My scruffy F6 mechanical renovation is nearing completion and I’m looking forward to driving it on the road for the first time.

Pictures of other 28IF's I’ve seen show 2 brass discs whereas mine only has one. Am I missing one, and does it matter? you'll spot that the +/- 5mm brass tube for the dizzy vacuum is also missing but I’m searching for one of those.

I’m not sure if my fuel pump is producing excessive pressure but as a precaution I’ll fit an extra gasket on top of the diaphragm . One contributor (who’s post I cannot find) added a piece of thin bore metal tubing to the fuel line to further reduce pump pressure. Any advice or experience of this?

The fuel inlet valve (controlled by the float) in the carb flops about and is not backed by a spring. It just flops in when you invert the carb. Should it be spring loaded?
Lastly, I saw Petak’s post from sowing a 28IF repair kit on Alibaba. I haven’t searched to see if its still available but has anyone tried it?

The Air Screw was 13 turns out. My van hasn’t seen the road for a few years but the engine starts and runs but I’ll turn it in progressively to find a happy medium.

Solutions or advice gratefully received!

 

[Boretto62!]

ciao .
e' vero che aumentando o diminuendo lo spessore del distanziale si puo' variare la portata della pompa carburante, ma è anche vero che i problemi nascono se la pressione è troppo poca , non troppa.
proprio per questo l'ago del galleggiante "chiude"al giusto riempimento.

alcuni mettono un secondo o-rirg sull' ago per "chiudere prima" evitando ingolfamenti.sono del parere che se la pompa benzina è originale e le tarature del carburatore anche ,,è meglio restare sulle regolazioni di serie
P.S. 13 giri mi sembrano troppi

 

[mojobaby]

Hi Bob, I agree with Boretto, 13 turns is way to much. Mine is 2 full turns out. Remember the air/fuel mixture screw is only for idle with the choke in the off position.
The float doesn't have a spring. When the bowl is full, the float rises and cuts off further fuel entering the bowl.

 

[R4-Bob-F6]

Ciao Boretto, Grazie mille, I’ll fit an extra washer under the valve if it helps.
Thanks Mojobaby I’ll start at 2 turns and see how it affects starting and idling.
Many thanks for your words of wisdom gents!

Any ideas about the (possible) missing brass disc in pic 2, or is this normal ?

 

[JdeW]

And about maintenance Here a nice page

DIego Yourself, Carburateur Zenith 28 IF

Apprenez à restaurer votre carburateur de type Zenith 28 IF pour votre Renault 4L ou Express

www.diegoyourself.com

 

[angel]

This brass disc is a plug for the idle circuit gallery and must certainly be there. Now your idle circuit is off, that's why the idle mixture screw is turned so far out and still has no effect.
You should have such a disc fabricated out of brass or aluminium and press it in the hole in order to have a fully functional carburettor again.

Fuel pump pressure is controlled by pump spring under diaphragm. In order to reduce it, you have to fit a gasket between diaphragm and pump body (under diaphragm). But I doubt it will produce higher than normal pressure.
Fitting a restriction on the fuel supply line will reduce fuel flow, which will lead to trouble on high speeds/loads.

 

[R4-Bob-F6]

Interesting and useful site (https://www.diegoyourself.com). Thanks for the link JdeW.
I have some aluminium so I'll get handy with the snips and bench grinder. I'll road test the pump as it is and modify it later if I have any problem.
Thanks Angel for your advice.