zenith page

There's a huge range of zenith carburetters.

Starting right back in the early 1900's .

The sizes start from 20 mm and go up to 48mm.

Where do you start to ,find out which one you have,

It's straight forward really your hand book or manual will give the type and specification's of the carburetter on your pride and joy .

If you dont have these or the carb fitted doesn't match then,

I always start with size ,ha dont listen to what they say size does matter

The flange ,measure the bore and then the bolt centers.The bore is the actual size of the carb ,this will be in metric e.g. 20, 22, 24, 26, 30, 33, 34,36, 37, 40, 42, 48,

English and European carburetters made under license are in metric .

This is always the first thing you should do ,because some Zeniths look exactly the same but can be different sizes.

Next look for numbers , on the float chamber side for early bronze zenith's and on the top for later diecast types .Or the bottomflange on later types.

The main body can have the details as well .The numbers normally start with the size and then the type, example,( 30 vig ) .It can some times be very difficult to identify the actual numbers and letters but dont panic I have most of the main parts books.

FIRST QUESTION do you really need to touch the carb at all ?.If it's running OK leave well alone ,if not then take the plunge.

So you have just got your carburetter off the car so what's next ,CLEANING UP

Thinners is good it's certainly cheaper than the little cans of spray once it's degreased you can begin work

This is where most problems occur

You must be very patient

Dont force any thing

If you break it !!!

Correct size screw drivers and spanners only ,try leaving the carb to soak in paraffin for a week .I quite often warm the carb up by pouring hot water over it ,this is not always the answer but it does work for me .

Most of the early carbs nuts / bolts are in bsw so bear this in mind.

Zeniths are very simple yet also efficient ,setting the float levels on early zeniths can be difficult but it does pay to get it right. Bottom feed float chambers with the needle and toggles ,these are the usual areas for concern .Try turning the toggles over to the unworn side .It wont help if more washers are put under the needle seating in the hope that this will stop flooding because to large or to many washers will effect the float level causing weak mixture .Bear in mind to that the heat from the engine will sink in to the carb and expand the fuel ,causing it to flood even when the engine is turned off .

Jets are used to meter the amount of fuel to other parts of the carburetter

.DONT put wire or needle's through the hole to clear it.

Compressed air is needed , you see if you put things in the hole you will very likely enlarge the jet size causing yet more problems .Later Zenith's have a square head on one of the float chamber bolts which is inserted into the jet to unscrew it .If the carb has not been apart before try the hot water trick ,boil a kettle let it stand for abit to cool the temperature slightly then pour it over .Be careful that you dont burn your self .

WARNING there is a risk that because the later type Zenith's are made from alloys which have a low melting point and may be effected by this ,YOUR CHOICE

Once the carb is apart clean all the internal parts carefully before inspecting them for wear .

Throttle spindles should be checked and also the throttle body ,any play here will cause bad running ,wasted fuel embarrassment when, it stalls in just the wrong place. Check the body for distortions especially the flange ,time and time again I get people telling me( the flange broke when I was tightening it up).If the flange has gone banana shape get a sheet of fine grade wet and dry put it on a surface plate or even a sheet of glass and wet it with paraffin .Then holding the carb gently move the carb in circular motions keeping the carb straight at all times .You will see the high and low spots ,

IT'S AS EASY AS THAT .

The spindle's will need to be replaced if there's to much play also the butterfly .This will mean the body will very likely need to be reamed out for either new bushes or over sized spindle's .When I have new spindle's manufactured I always have them made over size this makes it easier when reconditioning .

There's now another page for pictures of Zenith Carburetters I have done this to speed up the main pages on the web site, use the link below to veiw the pictures page