Problem Series 1

OK. Here's the problem.

I have an 86" late 2L engine series 1. The only none standard feature is a 34 ICH Weber carb.

It runs fine when cold but as soon you take it on a bit of a run and it gets up to temp it starts to sound asthmatic and stalls it you come to a stop. It will restart (Just) it you press the starter and keep your foot off the accelerator. When pulling away you have to slowly increase throttle or it starts to stall again. If you put your foot down to quickly it coughs and farts and then stalls (Not good in the middle of a busy junction.).

So far I've changed the fuel pump, coil, points, condenser, plugs and carb.

Any ideas. (I'll fill the rad with holy water if it helps.)

Carburettor icing?

Mine used to do the same. Got so bad it wouldnt start again till engine got cold. Turned out to be the diaphragm (spelling?) on the accellerator pump on the carb which had perished (I dont t5hink they like unleaded petrol very much). Could also be a partially blocked main jet. When the choke is out it will run fine even if main jet partially blocked) or as has been said, icing up. If it is icing, then it should start fine after standing for a minute. How new is the carb?

Thanks for that.
Mine will also do a complete refuse to start. Repeated start attempts with not a hint of starting then after about 5 mins will immediately fly in to life with a good start. (No half way house.)
The carb was bought off ebay. It had never been fitted but had sat on the shelf for a while. I'll check the diaphragm but the one I took off yesterday which was replaced by this one suffered the same fault (Or at least the car did.)
What is icing and is there anything I can do to stop it.
If the carb is icing up? and I replace the plastic spacer that sits on the inlet manifold with a metal one to conduct the heat from the manifold will this help or just cause more problems.
Thanks for the replies.

izasinner said:

Thanks for that.
Mine will also do a complete refuse to start. Repeated start attempts with not a hint of starting then after about 5 mins will immediately fly in to life with a good start. (No half way house.)
The carb was bought off ebay. It had never been fitted but had sat on the shelf for a while. I'll check the diaphragm but the one I took off yesterday which was replaced by this one suffered the same fault (Or at least the car did.)
What is icing and is there anything I can do to stop it.
If the carb is icing up? and I replace the plastic spacer that sits on the inlet manifold with a metal one to conduct the heat from the manifold will this help or just cause more problems.
Thanks for the replies.

Click to expand...

If it has done it with both carbs then probably not the carb (well, less likely anyway). You seem to have changed all the obvious other bits. Have you got an inline fuel filter? These carbs are prone to blocked jets if it is sucking ****e thro from the tank.
Icing is caused by damp air condensing and freezing on the outside of a cold carb. Removing the plastic spacer may help, if that is the problem. Make sure you seal the joint well though. Icing is usually worse with a worn carb or a poor seal with inlet manifold where air can be sucked in. Check the joint is good. If you drive it and it craps out, lift the bonnet quick and you should see a bit of ice or moisture on the outside of the carb. As soon as you stop the heat from the engine clears it. Try blanking off part of the rad so it will run hotter.

If it is worse without the plastic spacer and running hotter, then it could possibly be fuel vapour lock, but try the above first.

Thanks Worf I'll give the carb on manifold no spacer a go. The more I look at this the more I think it is a fuel air mix problem. Sorry for the numpty question but what is vapour lock. I always wanted to gen up on engine mechanics but now I've bought a series 1 it seems to be a necessity.
Nick

izasinner said:

Thanks Worf I'll give the carb on manifold no spacer a go. The more I look at this the more I think it is a fuel air mix problem. Sorry for the numpty question but what is vapour lock. I always wanted to gen up on engine mechanics but now I've bought a series 1 it seems to be a necessity.
Nick

Click to expand...

Just t5he opposite of icing up really! Modern unleaded fuel is apparently more volatile than leaded, so it turns to vapour at a lower temp. If the fuel system gets too hot, it can vapourise before it gets thro the carb and you get "vapour lock". If removing the spacer makes it worse (bcause the carb is hotter) then that is whats happening. Try it first and see what happens. What about the dirty fuel possibility?

Thanks again. Don't think it's dirty fuel. Tanks new and the in line filtre is clean. Thanks for the explanation of vapour lock. I think I can rule that out. the carb was definately cold the last time it played up although the inlet manifold was hot. I'll come back once I've taken the spacer out and given it a run. If it's not that I'll have to look at the dizzy. There is a bit of wobble in the shaft but not stacks.

Carb icing is caused by DE-pressurisation of air... and especially cold damp air like in wintery evenings and mornings.

It's the opposite of a bicycle pump getting hot when you pump (compress) air.

When you DE compress air it gets COLD, and with a big engine sucking thousands of litres of air a minute through the venturi of a carb (where the pressure drops) the body of the carb inside and out can soon become solid ice. It's ice INSIDE that causes all the bother. And the temperature can become extremely low from this cause.

Old days cars tried to get round it by piping the inlet air from a tin box thing round the exhaust manifold to heat the air before it went into the engine. This usually worked.
You could rig something like that quite easily.

Even the air filter causes a small pressure drop, and with it a temperature drop too.

You could arrange an air box on the exhaust maniold, and pipe heated air to your air filter. I bet early LandRovers did just this in petrol versions.

I think this would solve your problem.

CharlesY