Thread: 2.25 petrol - poor running with Zenith

A long-winded update on this - I was sitting around stewing over what could be going wrong, and I thought that maybe there was still a bunch of excess fuel lying around from previous over-rich attempts at starting it.

After a couple of hours of letting it sit, I wound the idle mixture screw to 1.5 turns out. Importantly, I didn't press the accelerator.

It started easily, and ran much better - a little lumpy, but no backfiring and it stayed alive.

While pressing the accelerator pedal for the first time after starting, nice and slowly, it started dying, and lifting off didn't save it.

I let it sit again, then disconnected the accelerator linkage at the carburettor. I got it idling just like before, and tried gently applying some throttle at the carburettor itself - same thing, any throttle at all killed it. Even 10mm of travel. This rules out accelerator linkages/adjustment in my mind, which was a risk because I had to turn two of the levers back to front to reverse the pedal direction when going from the Solex to the Zenith.

I was about to experiment with clamping off the vacuum hose on the hypothesis that ignition timing was out and the vacuum advance when opening the throttle was killing it, when I noticed that the top of the fuel pump was wet. I cranked it over after turning off the ignition, and sure enough there was some sort of leak there.

I've ordered a (Britpart, unfortunately) fuel pump in case the pump itself is causing the leak. It could be the linkages but the current pump is 60 years old, and I was very careful with the linkages to get them tight.

But that's not the end of the story - while putting my hand down the right-hand side of the engine to check said linkages, I bumped the distributor - and the body rotated quite freely. So that's the second thing I need to fix, since timing is probably all out of whack compared to when it was (allegedly) running well with the Zenith.

What a state to get the car back from the mechanic in! At least I have a few things to pursue now, rather than sitting around thinking about it.

Any advice is still welcome, like I said - I'm a newbie.

I am not a petrol expert as some of my posts attest with my recent zenith stromberg carbies on a V8. I would start with removing the carburettor and draining the fuel bowl, remove the bowl carefully whilst holding the carburettor upside down. Once removed you will see the fuel float, check it is not full of fuel from a leak, if it is empty ( a good thing) still holding the carburettor upside down check the fuel bowl height relative to the housing there is a measurement it needs to be set at. Before adjusting the float height you need to remove the pin that the float hinges on and carefully remove the needle from its seat. Check the needle for wear and if the needle is damaged it will require replacement. With the needle installed in its seat blow through the fuel inlet port to check the needle seals if it doesn’t this can cause the carburettor to flood the engine. Now replace the float and if the height is correct look at the jets and check you can blow through them, if not remove the jets and clean the orifice. Take care when cleaning the jets they are of a specific size and need to stay that size so using a fine piece of wire smaller than the jet size remove any blockage. As well as cleaning jets clean the ports in the carburettor that the jets are removed from, reassemble the jets. If all the ports are clean reassemble the float bowl, next check the idle / air fuel screw seat it should not be damaged from over tightening and appear as a small orifice on the inside of the carburettor throat. The needle should also be clean and undamaged, for initial setting I use what I was taught on old EH holdens screw the screw in very gently till it bottoms out then back it out 1.5 turns. Assemble the carburettor back on the engine and wind over with the starter until hopefully it starts. You can adjust the fuel/air screw after the engine idling evens out. One other thing I would check whilst the engine is immobilised rotate the motor with the crank handle to get the motor To the required timing mark before top dead centre No.1 cylinder then check the distributor is open and pointing to the number 1 plug lead. If all is well hopefully you will have an engine that runs.
Gippy

Thanks Gippy.

The Zenith is a brand-new carb, a cheap copy but still new. That doesn't mean it's good, so if the new fuel pump and ignition timing don't get it, I'll certainly follow the advice in your comment.

Regarding timing - my 2.25 is a very early example and has the timing marks on the flywheel, so I was trying to put that off because it's a proper pain in the neck. Given how loose the distributor was, I'll have to come to terms with doing it :-(

- Will

If my memory serves me well enough… wasn’t there an issue with these zenith copies where you had to give them a rub with wet and dry on a flat surface to get the top cover flat and stop it sucking air?

I fitted a reconditioned solex to mine that I bought from the mob in Cyprus

Never looked back…

> wasn’t there an issue with these zenith copies where you had to give them a rub with wet and dry on a flat surface

I've heard the same. If fixing the other more obvious problems doesn't get it sorted, I'll give it a go. It seems unlikely since that sort of warpage would more likely cause a vacuum leak (and therefore lean running), but it's an easy enough thing to try.

> I fitted a reconditioned solex to mine that I bought from the mob in Cyprus

Do you have a link? I'd like to stick with a Solex for originality.

Originally Posted by WhatIsClocks

> wasn’t there an issue with these zenith copies where you had to give them a rub with wet and dry on a flat surface

I've heard the same. If fixing the other more obvious problems doesn't get it sorted, I'll give it a go. It seems unlikely since that sort of warpage would more likely cause a vacuum leak (and therefore lean running), but it's an easy enough thing to try.

> I fitted a reconditioned solex to mine that I bought from the mob in Cyprus

Do you have a link? I'd like to stick with a Solex for originality.

it will be on here somewhere ...

Even with the original Zenith carbys I used to have trouble with them running rich (usually on a slight uphill slope). Problem was always fixed by rubbing both top cover & matching surface of bottom section of carby until I achieved a good seal between the two surfaces.
The warping problem is IMHO caused by the fact that there insufficient securing screws around the throat of the carby. Before rectifying it I could slip a thin feeler gauge between the two surfaces in the area of the throat but not around the float chamber. So maybe you could check that.
However, it sounds like your problem is with your loose distributor rather than your carby.
What part of Australia are you located? If close by I (or possibly some other AULRO member) could maybe have a look at it for you.

Originally Posted by Xtreme

What part of Australia are you located? If close by I (or possibly some other AULRO member) could maybe have a look at it for you.

Thanks Roger. I'm in Sydney - Bankstown specifically. If anyone offered I'd definitely take it up, but probably in two weeks' time or so, once I've had a chance to address the known issues.

It would be good to get someone with a bit of Land Rover experience to take a look at it, and just listen to it running for an overall check. I couldn't find anyone who works on Series vehicles to do a house call.