It's not easy to see, since the carburettor hasn't yet been cleaned, but the nylon bushing for the accelerator pump pushrod looks as though it's damaged, hence the use of a spare choke spring to prevent the pushrod from falling out.

There's something which always seems to happen with these single choke carburettors if they've not been used for a long time; the ball bearings which act as non-return valves for the accelerator pump don't move freely and some light tapping may need to be applied in addition to that business with soaking in solvent & blowing through with an air line...

Right-oh! I've dumped Mr Carb in a petrol bath and he's going to soak for a couple of hours. The weather's horrid here today, so I'll concentrate on this and finishing off the valve lapping and stem-seal fitting.

I like your style, sir!

Now, hot wash, or cool? With detergent, or not? Dismantle the carb first, or chuck it in whole?

In the bath:


Ken was dead right about the extra spring holding the accelerator pushrod in place:


Took it apart and had a look inside, cleaned all the jets, and inspected the float. Everything looked good... I think!


Ken, re. "the ball bearings which act as non-return valves for the accelerator pump don't move freely and some light tapping may need to be applied..." Which ones are they?

In the bath:


Ken was dead right about the extra spring holding the accelerator pushrod in place:


Took it apart and had a look inside, cleaned all the jets, and inspected the float. Everything looked good... I think!


Ken, re. "the ball bearings which act as non-return valves for the accelerator pump don't move freely and some light tapping may need to be applied..." Which ones are they?

Smiffy,
the easy one is inside the brass fitting just beside the float in your last photograph.
Unscrew it, hold it close to your ear and shake it.
If the ball bearing inside isn't loose, a combination of prodding with a cocktail stick and tapping ( dropping?) it should free it off.

The other one is more difficult, so will double check tomorrow before offering advice, but a blow gun/airline are usually needed, if memory serves...

Re. that damaged nylon bush, I've probably got a carburettor here that's past saving which has a servicable part on it.

Great, thank you. I'll await further info.

Had to sort out a single choke carburettor for a Mehari yesterday, so here's a photograph showing one of the locations where you need to point a blow gun to free off the second non-return valve in the accelerator pump setup.
There's also the 'outlet' port on the top surface of the carburettor body; if repeated shots of compressed air fail to dislodge a ball bearing that's stuck, a few taps of the carburettor body against a piece of wood may help.
Test the functioning of the accelerator pump with the lid off the carburettor; you may need to flick the lever a few times with it disconnected from the pushrod to prime the system.
Avoid trying to pull the pushrod out of its socket at the spindle end, I guess you know what can happen to ancient plastic bushing that's become brittle with age.

020 by slcchassis, on Flickr

Will have a look for the box of single choke carburettors tomorrow to find that spare piece for your carburettor.
It's a bit frantic at the moment, with a couple of chassis to send off to Australia, a 1960s chassis to build for a customer in Israel and a race chassis order from Pete Sparrow...

Thanks for this info, Ken.

If you're busy there's no rush for me to have any potential spare bit...I have loads of other jobs that I could be doing... including getting busy with the compressed air blower.

Just been trying to get at the last of my valves, to change the seals and lap the valve. Can't budge that pesky bolt holding the rocker! And now the head is getting mis-shaped. What to do? Cut a slot and get it out then replace? Or is there a way to rescue my hamfisted fuckup?