Carbs

[Keith Clements]

So go back to using the non recon bowls, floats, valves and washers. It is unlikely the recon of the body would prevent starting unless it was done very badly.
So if it still does not start then I would check ignition timing and perhaps use a separate battery for the coil just to make sure it is getting a good spark.
If you pour a thimble full of fresh petrol into each carb prior to starting it should prove if it is lack of petrol. Or use Easystart.
It is cold now so comparing starting when it was warm is not valid.

[Barry20383]

The battery seems to have plenty of power and have taken off one plug lead and put it to a spare spark plug and have a good spark . I assume that if one carb has a problem the good carb would allow two cylinders to fire or at least give a kick. I can try the lowest needle valve washers 1 mm if not will check the head carb gaskets in case of suction leak they seem tight have a suction gauge could check this. I did try putting small amount of petrol down each carb but not even a kick . The timing was ok before i changed the carbs will check again.
Thanks.

[Keith Clements]

Try Easystart if all else fails. Modern petrol seems a bit reluctant to evaporate.

[Forumadmin]

Just another thought. A weak mixture (and hence poor starting) can be caused by poor sealing between head and carb body in any of the four gaskets. Not easy to detect if it will not start, but easy once it has with a length of hose stuffed in your ear.

[Nick Webster]

I have probably said this before somewhere but I'll say it again because it is a particular hobby horse of mine. If a car has been not much used but modern petrol has been left in the tank for a while there is a good chance that the fuel has had time to dissolve some of the crud that has accumulated in the tank since day one. It becomes a sort of marinade sauce. This accumulation is a result of some of the treating methods used in ye olde days of petrol production and is of a chemical origin, rather simple debris. If you are regularly running the car and your turn over of fuel is higher, then it does not get time to be seriously contaminated so the problem does not become apparent. The problem is that a lacquer forms on the spark plugs. This results in tiny ineffectual sparks all over the place or sometimes complete short to earth without a spark. Given the right conditions it can happen quite quickly and affect new plugs in a matter of hours. The cure is to cook the plugs over a gas flame, but it is not always effectual. The obvious answer is to always have some new plugs on hand. Sometimes rough running can be attributed to this, so in that case changing the plugs is always worth a try.

Nick

[Forumadmin]

The car started on the 21 Dec but was not running well.
Barry then tried to solve this.
On 27 Dec he discovered petrol was leaking which was the result of the new needle valves he fitted.
Then it would not start. So it would start with an excess of petrol but not run properly.

So the mixture is either not rich enough to start or the petrol is not good enough.
Easystart should prove this or a thimble full of just purchased petrol is second best. Put this in with the choke open then close the choke. Warming the plugs up before starting might also help.

I would check that the choke is fully closing on both sides and that the choke throttle advance is operational.

It is also possible that the distributor is not functioning correctly and so will not start with this different mixture.
Slightly worn distributors give too much advance at starting revs which may be OK with an over rich flooding mixture but not for the weaker correct mixture. So retarding the ignition might assist starting. But the solution is to recon the dizzie.

Whilst the battery may be good I would also check the voltage at the feed to the coil when the starter motor is running. This should remain above 10 v when cranking. A bad earth will cause a voltage drop. Or as I said fit a separate battery to the coil, but disconnect lead to the rest of the car or you could melt the loom! I use my emergency boost pack for this.

You can end up chasing your tail which is why it is important to document each step you take and hope you can get back to where you started.

[Barry20383]

Have rigged up a temporary start button to make it easy to turn over the engine from under the bonnet.
On checking with a Dellorto carb balancer have found that the passenger side carb has no suction the other carb is showing 6 . Have checked compression on that side and is showing 140 psi on both cylinders.
Have now removed the carb and tested the suction direct on the head which is showing good.
The carb gaskets look good and have been compressed.
Will have to examine the carb.
Barry

[Barry20383]

Have checked the suspect carb off the car with suction from a vacuum cleaner gauge showing maximum suction. Have now replaced the carb back on the car with a new gasket and now have suction. Also have replaced the coil with a new one and have good spark. The car is still not starting not even a kick. Have ordered some quick start spray to check if it will fire if not needle valves may need further adjustment it now has 1.5 mm washers. Will also check timing but it was running but rough before carb change.
Barry

[BarryCambs]

I'd strongly recommend not using easy start, having seen what it can do to engines. It's great for starting dead lorries and tractors to move them to a scrap yard, but while the engine will certainly fire on it, it doesn't really rule anything out.

I had this very problem on a Zenith carb I overhauled for a friend's Mk2 Zephyr a couple of years ago. After a lot of head scratching, it turned out there were 2 different size/taper of needle vales and the one in the rebuild kit was the wrong one for the original seat, which is what you seem to have found as well.

As Nick suggests, I'd make sure the petrol is nice and fresh. We've been having problems with motorbikes standing for a few months. Some vehicles seem more sensitive than others for some reason. My friend has 3 bikes stood next to each other in the same shed. All were filled from the same jerry can at the same time. Two or 3 months later, one started first time, the other two refused to even fire without fresh petrol. The Long Two sometimes struggles to start ad run properly if the fuel's been in more than 6 weeks. I suspect most of the volatile parts have been lost as the tank breather is rather generous and the garage always smells strongly of petrol. It will cough and splutter for a mile to the petrol station, feeling as if it has water in the carb, but within a hundred yards of filling up, its like a well oiled clock! The Honda lawnmower filled with the same petrol always starts first pull in spring, with the petrol that's been in it over winter

[Barry20383]

Have changed the fuel a week ago. I replaced the new needle valves with the old ones which has stopped the leaks. I have tried 2mm and 1.5 mm needle valve washers with no joy still have 1mm left to try.
Perhaps the fuel level in the float chambers is still too low. Will check timing have fitted a new coil have a good spark.
Barry

[alexander]

Hi Barry
I had problems with my carbs that always seemed one step forward and two steps back, leaks, fuel level, poor running etc. After working through every thing and thinking I’d fixed all that could go wrong the car would not start easy and some times not start at all. The problem was dirt/ rust being pulled through from the tank, every few days I’d find dirt in the float chamber and pump. I took the petrol gauge sender out of the tank so I could see the condition of the tank and there was lots of crud in the bottom . I ended up taking the tank out to clean and seal, problem solved. If you do decide to have a look in the tank do remember to remove battery leads as the last thing you need is a spark .
Hope you sort it soon
Dave

[Barry20383]

I drained the tank out and flushed it with a gallon of fuel before filling it. The car is also fitted with a modern clear plastic fuel filter. Have taken the bowls of several times to change needle valve spacer washers have always found the bowls clean. The car when i got it had stood outside for a long time it was running and starting but couldn't get it to pick up so fitted re con carbs as the old ones looked worn out.
This has caused all the problems.

[Nick Webster]

I would just like to endorse BarryCambs comment about Easystart. I work a lot with old diesels and it is a recognised problem that engines will become addicted to it and then will not ever start again unless Easy start is used. For a short term advantage that proves nothing it can inflict too much damage in a classic engine.

With regard to my previous comments regarding petrol contamination, which to elaborate, is caused by Sulphur compounds that no amount of filtering will clear; I note that one of your previous postings mentioned a good spark using a spare spark plug. Really a test should be done on the plugs you are using. Bear in mind it has to be a nice healthy spark because under cylinder compression it will be slightly less.

The fuel passages in the Zenith are rediculously tiny and can be easily blocked . Check by using a small pipe (windscreen washer style) on the various openings. Blow with your mouth and put a bit of soapy detergent where you expect to see the air exit.

Finally, I doubt that the float level will prevent the engine starting as this is not really critical. Don't get hung up about it. Correct adjustment is probably something that would show in petrol consumption over a period of many miles. As an example, I have attatched a photo of a Zenith bowl that was put on "bird-beaked" Amazingly it does not appear to have leaked, the engine ran and the car was even being driven about.

Nick

carb.jpg

[Barry20383]

Thanks Nick.
Have fitted a new coil plugs and plug leads as all the leads and caps were mixed. Have set the plugs to 25 tho
The compression is 140psi will take out a plug and check the spark. I assume if it was a carb problem the good carb would allow its 2 cylinders to fire or at least kick.
Or is the above not possible due to having a balance pipe.
Will double check the timing and remove the rocker cover to check both valves are closed and on the compression stroke.
Thanks for your help Barry.

[Nick Webster]

Barry,
Everything you have done regarding electrics sounds fine. Of course if it was running before you took the carbs off there is always a possiblility that by starting work on the electrics, you have introduced some other failure mechanism that is completely clouding the issue. As far as fuel contamination goes, if there was, or still is a fuel quality issue, this would not affect plugs imediately so it should at least start.

There is only one other thought I have. This is now fairly old news and I would have expected all the stock to have passed through but having fallen victim to this I can vouch how final it is to the running of the car. That is a short circuit in the rotor arm due to the type of plastic. If you have a really old one try that. Long shot but we seem to be into that now.

I should have added that with my picture of the crooked bowl, almost certainly the car was starting on the other carb and this side only really kicked in with the main jets. Slow running was not very slow! This rather indicates to me how crazy it is if the car won't go if you have a twin carb engine. You would think one of the two would step up to the plate.

Nick