Rotating distributor

[Scallops]

Hello Folks - a few questions if I may....Does the Series 1 original Lucas Distributor actually rotate by undoing the base screw? Mine won't budge. (I know there are 2 screws)

Now - my vehicle now drives perfectly with the choke out half way. No backfire. Slight backfire from carby (not exhaust) with choke in and revving engine. So might I try enriching the mix via the mix screw? The static timing is set and the distributor is as retarded as can be (as retarded as me! ) - as set by Blknight.

But I read elsewhere that retarded timing can be the cause of a carby backfire....

Can someone knowledgeable on this motor (2litre spread bore) give me some straight answers here?

- might a fully retarded distributor cause the carby backfire?
- as it drives fine with choke out, should I advance the timing a little and enrich the mix a little?

[Timj]

Hi Dan,

I'm not an expert on either the Solex or the 2 litre (not an expert at all, really ) but in general a carbie's mixture screw only controls idle mixture. Above idle there is enough vacuum generated within the carbie to drive the normal circuits where the mixture is controlled by the jets and an accelerator pump of some kind that reacts when you first press the accelerator to give an extra burst of petrol. So given that the car is idling properly I don't think you need to play with mixture. Given experience with other engines then timing not being right can certainly cause backfires and poor running.

Are you setting the timing with a timing light or statically (lining things up then turning the dizzy until the points spark)? I would set the engine initially to the recommendations in the manual then you can advance it from there until you get pinging under load, then retard it just a little. If you are using a timing light you can rev the engine and make sure that it advances, you can also see if there is wear in the distributor by how solid the light is on the mark, if the mark is moving around around and is hard to tell if it is sitting in one spot then there may be wear in the distributor causing erratic timing. Also check that your leads are all good and have tight crimping onto the plugs and dizzy, points are clean and flat surfaces and that the plugs are set to the right gap and are also clean with no signs of arcing across to the insulator.

The process of setting timing is also a bit of a trial and error thing in that the timing varies with the revs and the revs vary with the timing so, once you set the idle revs and mixture, you then set the timing, that changes the revs so you then reset the revs and mixture, that changes the timing so you then reset the timing and so on until it all sits properly.

Hope that helps a little at least.

Tim.

[Scallops]

Hi Dan,


Are you setting the timing with a timing light or statically (lining things up then turning the dizzy until the points spark)?


Tim.

Both. So there is no direct relationship between being fully retarded and a backfiring carby? If mix only effects idle, I wonder why it runs fine with some choke?

[wrinklearthur]

Hi Scallops

We will try again, with this, using the series I, operators, parts and workshop manuals, as references.

Does the Series 1 original Lucas Distributor actually rotate by undoing the base screw ?

Yes and to remove the distributor from the motor.

The clamping plate, P/No 245003 has two fasterners;
one, is a clamp screw horizonialy located through the clamping plate, this is slacked to turn the distributor in the distributor housing assembly, P/No 214047
two, is a special set screw, P/No 215758 that fixes through the sloted hole in the clamping plate and removing this screw is the easiest way to remove the distributor from the motor.

Now - my vehicle now drives perfectly with the choke out half way. No backfire. Slight backfire from carby (not exhaust) with choke in and revving engine.

That back fire is when the motor is running lean, it isn't getting the correct amount of fuel under load.
First, I would check that the fuel pump, is delivering a steady amount of fuel to the point where the fuel line P/No 218955 meets the carby, undo this and get someone to turn the key on and you watch as the petrol is run into a jug, there should be steady flow of petrol at that point.

Let me know when you have done this, as there maybe a blockage elsewhere.

So might I try enriching the mix via the mix screw?

That only sets the idle mix and is easy to do when everything else has been made correct.

Cheers Arthur

[Scallops]

Thanks Arthur! The fuel pump is bellowing fuel out to the carby - no prob there. I'll persevere with trying to rotate the distributor then.

I'm close to getting this right and appreciate your patience and help.

[series1buff]

The series 1 engines can be a **** of a thing to tune . Looking through the UK forum, you see many people with engine tuning and other fault problems. I had a lot of trouble myself .I played with the petrol pump , carby and the electrical side of things .... thank god it runs OK now . They are rather fussy and you have to be 'IN THE BALLPARK' otherwise it won't perform.

Compared to the other older vehicles I have owned, these cars are a nightmare to get running correctly.

The petrol pump is a low pressure thing ..you want it to be around 1.5 psi .. that's all.. if its higher the carby will flood . The needle/seat in the carby is a left over from gravity feed systems from pre war cars.

The carby will seep petrol from just about every orifice .... I always look at restored series 1's under the bonnet..more often than not, you will see a petrol stain all over the carby ... the gasket between the acc. pump housing and the main body is a big culpret for that .

Mike

[wrinklearthur]

The fuel pump is bellowing fuel out to the carby

Hi Scallops

The next thing to check is, to see if the petrol is passing through the needle and valve seat P/No 260164, quickly enough.

So next, undo the three screws P/No 512401, that hold the top cover P/No 260165, of the carby down.

Now, repeat the test as done before, but this time have the fuel line connected to the carby cover and checking that joint doesn't leak, hold the cover over your jug and at the same time operate the end of the needle, so it closes and opens the valve.

Things to look for;
Does the valve stick shut at all? if it does stick shut, replace the needle and valve seat P/No 260164.

Is the flow of petrol out of the valve, good or is it very slow? If it is slow, there would be blockage either in the needle and valve seat P/No 260164, or the gauze filter P/No 260168, ( this filter is contained by the special bolt P/No 260167, that passes through inside the banjo union P/No 260166 and screwed into the carby cover ).

Cheers Arthur

[Scallops]

Hi Scallops

The next thing to check is, to see if the petrol is passing through the needle and valve seat P/No 260164, quickly enough.

So next, undo the three screws P/No 512401, that hold the top cover P/No 260165, of the carby down.

Now, repeat the test as done before, but this time have the fuel line connected to the carby cover and checking that joint doesn't leak, hold the cover over your jug and at the same time operate the end of the needle, so it closes and opens the valve.

Things to look for;
Does the valve stick shut at all? if it does stick shut, replace the needle and valve seat P/No 260164.

Is the flow of petrol out of the valve, good or is it very slow? If it is slow, there would be blockage either in the needle and valve seat P/No 260164, or the gauze filter P/No 260168, ( this filter is contained by the special bolt P/No 260167, that passes through inside the banjo union P/No 260166 and screwed into the carby cover ).

Cheers Arthur

Seat valve and needle functioning correctly - new needle had been used. Float working fine. Gauze cleaned out in carby cleaner.

[wrinklearthur]

Hi Scallops

We'll keep going along with the lean mixture theme, Is there any chance that two washers, or too thick a washer was fitted between the carby cover and the body of the needle valve and seat, as this would cause the float level to be too low?

How good is the intake manifold surface and its gasket?
Also have you inspected the intake manifold for any corrosion holes or stress cracks, that may have developed?
Can you fit a vacuum gauge, to do a run and tell us what the results are?

Cheers Arthur

[Scallops]

Hi Scallops

We'll keep going along with the lean mixture theme, Is there any chance that two washers, or too thick a washer was fitted between the carby cover and the body of the needle valve and seat, as this would cause the float level to be too low?

How good is the intake manifold surface and its gasket?
Also have you inspected the intake manifold for any corrosion holes or stress cracks, that may have developed?
Can you fit a vacuum gauge, to do a run and tell us what the results are?

Cheers Arthur

The carby cover and body where the needle and valve sit are attached by 3 bolts (2 on the upside and 1 facing down at the rear) with spring washers - these are fine. Float action was checked to make sure float actually floats and has no small holes.

Intake manifold gasket is as new - was replaced when I got her only a matter on a year or so ago - it's all good.

Don't have a vacuum gauge. But I feel the issue is simply in the mix ratio and the timing - it's fully retarded, as set by forum member. This is a well known culprit for carby backfires, is it not?