Won’t idle

Hi
I have a 73 bay my problem is I can’t get it to idle, I’ve tried 2 solex 34 pict carbs on it, both working previously, it’s a 1600 Standard engine,
I’ve cleaned jets and replaced some with brand new jets changed gaskets and given them a thorough clean. Apart from the carbs what else could it be the causing the problem.
I’ve checked for air leaks but can’t find any. Ty

 

Valves check and gap.

 

Timing - have you checked this? So adjust the distributor to get 7.5 BTDC on the crank pulley with a strobe. 7.5 is for 2 litre type 4 engine, so you’ll have to check Haynes manual for 1600cc type 1 engine

 

Does the idle shutoff solenoid click on the carburettor as you turn the ignition on? Or another way to to tell : if you have the ignition on and you pull the wire off the tag on the cylindrical solenoid on the left side of the carburettor it should click.

The idle solenoid controls fuel feed into the idling circuit.

With the choke warmed up and the throttle lever screw not quite rouching the stepped cam, the idling circuit is entirely controlled by the big idle speed screw and the idle mixture screw.

If your throttle butterfly is slightly open at idle you can have a lot of trouble setting idle with the two screws on the side.

Also check for silly air leaks like split hose to distributor or the hose going to the hot air flap in the air cleaner if you have that.

Finally it could be simply down to not having the right air cleaner setup. If its a shiny small chromed pancake rather than big ugly boxes you have a problem.
Show us a picture of the carburettor setup.

 

Air leaks?

 

A photo of your engine bay can also be helpful

 

I’ll give everything A go over weekend meanwhile here’s a pic of the engine bay

 

Straight off there are two brass pipes on the carb that should be capped.

 

Yep. It’s never going idle (or run) properly with those two pipes open.

 

And thats before we predict how your next post after you get it running is "but it still dies at the end of a run" ... With that air filter it will provoke condensation/ icing ... ..

 

Thanks for all your help it’s much appreciated
After plugging the pipes up which I forgot to take off the other carb I then started it without the
Air filter on and it Now ticks over its a bit rough but at least it works,
There was condensation in the filter so seems like what you say is right about them.
Any recommendations or pictures of what I should be buying for air filters would be appreciated.
Ty for helping a complete novice out.
Andy

 

If you have a circular shelf to the right of the engine, that is the stand for an oil bath air cleaner. That is then connected via a plastic elbow to the top of the carburettor.
If you have a bracket with holes there you have a fitting for an air filter box (later buses )
If you have a sawn off stump, you can choose which air cleaner to fit, but you will need to locate a replacement bracket or shelf.

Both of these have a hot air pickup hose and a means of controlling the air temperature going into the engine to 30 degrees C.
Which helps keep down the carburettor condensation and hesitation.
This recent thread discusses @redgaz story of his air cleaner..

https://www.thelatebay.com/index.php?threads/air-filter-thermo-vacuum-part.89846/


My engine bay the air cleaner is to the right, the pipe crossing to the carburettor, the box on top of the carburettor are to do with my using a Weber progressive carburettor.

The hot air pickup goes up from a pickup tube that points at the No2 cylinder head. It goes up into the air snout of the air cleaner. Where a vacuum operated flap controlled by the thermostat on top of the air cleaner serves to control the air temperature leaving the air cleaner going to the carburettor.

 

Took the van out this morning and it spluttered and cut out a few times I limped home,it ticks over nice but bogs down when you put ya foot down

 

Have you had it running nicely on cold mornings with that setup before? That dissy and air filter combo is about the worst you could have for cold running.

It would be wise to set the points gap and valve clearances before you go to far though.

 

I find when setting up that when you set the idle speed, then the mixture , with the textbook lean best idle approach that it stumbles unless you wind the mixture screw out a bit under a quarter turn.
Its quite sensitive.


But first set the tappet clearances and the timing.

Buses shouldnt stumble and faff, should pull smoothy away like a 1.0 Nissan Micra..

 

Hi sorry to be a pain
My van now idles nicely but seems to stay on the choke also you can visually see fuel draining out of the fuel filter with air bubbles coming from the fuel pump And empties any ideas ?
TIA

 

How do you mean staying on the choke? The choke won’t be able to slowly open unless you operate the throttle arm to take the pressure off the fast idle cam (as you would do driving along). It won’t open just sitting there idling.

 

Air bubbles from pump isn't good when you consider how they would get in.

Any fuel in the oil?

 

What you might have is a blockage of the fuel pipe between the bottom of the fuel tank and the pump.
From rust settled in the pipe to the fuel sender label resting on the pickup pipe in the tank.


The stock fuel pump has quite impressive suction capabilities, so it could be drawing air in through a crack in a join in the fuel line, between the blockage and the pump. This crack might appear as a slightly 'wet' area when the engine is stopped, or possibly the petrol leaks and evaporates so fast you wouldnt see it. If you were using old fashioned fabric coated hose, it might show up as a dark 'clean' spot on the braiding near the leak.