Mk1 1.7 V4 carburettor 1972/3

[Mikexx]

The carb on my camper has history. It was replaced a long time ago with a Zenith 361V or is it "36 IV" from a Ford Corsair. I don't think I have the old one.

The camper has been stood still for some years and so trying to get it gong again. I purchased one of these:
https://www.ebay.co.uk/itm/256072293421
A "Zenith copy 361V" which I assume is a Chinese clone. It looks fairly well built but had to modify the fuel inlet as this one fouled the distributor.
The float side was initial leaking fuel and overflowing. This was cured with some PTFE tape on the seat to seal the thread. There is no longer a dribble into the venturi.

The engine runs, but runs rough. It feels like it is over-fuelling and over-rich. It won't idle. If I close the choke strangler it doesn't like it.

I note this new carb is for a 2.25 Petrol Landrover and hoped I might get away with it, but obviously not. Hindsight is a wonderful thing!

I believe this carb was only fitted prior to 1968 with Motorcraft one after this date. In theory I should therefore have this one although the mounting is the same.

I am hoping for some advice, is the jetting such I can transfer parts across or should I consider another way forward? The Motorcraft carb availability seems like he's teeth.

[dumper]

I can’t remember if it’s the same as the motorcraft one but you should be able to change the main jet in the bottom of the top half it will have a number on the brass jet back in the day it was easy to get different jets not sure were to nowadays.
Another thing that can effect the mixture is the float level if set to high it will be to rich.

[Mikexx]

Thanks for your input.

The first Zenith 361V worked fine and so must have been jetted ok, sufficiently well for a good running engine.

I am thinking of swapping the jets over. They will need some cleaning as they're covered in white powder (of the zinc/aluminium oxide variety).

The float level should be fine, and might even be a little low. I'm paranoid of the fuel dribbling into the venturi. It has an electric pump so fuel is under pressure even when stationary.

[dumper]

Yes swap the jets over should have a number on them,when we used to fit twin forties carbs to escorts we used to to fit a filter king pressure regulator to them to control the pressure

[DougT]

Also it might be worth checking what the electric fuel pump does when you block the outlet. I think the electric pumps intended for use with carbs have an internal return system so as not to overpressure the float needle.

Some carbs have a return line back to the tank but it sounds like neither your old or new carbs have a return line and maybe the Zenith float valve was better at dealing with pressure ?

Doug

[Mikexx]

Many thanks for the posts.

I swapped the main and compensating jets and it now runs. In fact when hot it seemed to be running lean.

I straightened the servo assist pipe and the revs increased. Another tell-tale sign was that removing plug lead 2 from the distributor cap had no effect whereas the others did.

Fitted new vacuum servo pipe and ran a little better, but still no change in idle when plug lead no 2 was disconnected. Clamped the servo pipe and this time and it stalled.

I've refitted the master cylinder and used some silicone sealant just in case there has to be a air tight seal there but not had a chance to run and check if No 2 is still weak or misfiring.

Is this a common issue? Do servos leak? Can they be repaired? Do replacements exist?

[dumper]

I’ve had servos leak in the past out of the piston rod and just changed it never looked into repair but maybe possible as for misfire on cylinder number 2 do the usual checks plug / lead /compression / valve clearance

[Mikexx]

Thanks for the reply.

Do you mean leaks on the cabin side?

I suppose I could collapse the pipe or blank the 'inlet' to confirm.

I swapped plugs but haven't carried out any more tests. I'm more pleased that it runs after being stood still for over 10 years.

[dumper]

No I mean if it’s missing on number 2 make sure it’s not low compression piston or a valve problem

[Mikexx]

A belated thanks for the reply.

I am getting a compression tester shortly that will be able to confirm any loss of compression.

It's not easy to start and when hot dies and becomes even more difficult to start, I'm hoping the issue is with valve clearances and nothing more sinister. No oil is burnt and very little blow-by so assuming top-end.

For anyone who would like to know the background, please feel free to visit this Facebook group, join and and share:
https://www.facebook.com/groups/420541793938956

I have a court hearing on the 14th May to decide whether the local council order will be upheld and has to stay on a busy road rather than our driveway that can accommodate a number of vehicles.

[Mikexx]

I am happy to say that the council has relented and now allow me to park the camper on my drive rather than on the road.

I took some compression pressures and have the following:
..........Dry(psi) Wet(psi
Cylinder 1 176 199
Cylinder 2 136 150
Cylinder 3 154 181
Cylinder 4 126 146

While there is some variation it implies that things aren't disastrous given this engine hasn't been used in earnest for 10 years.

Much of the rough running was sorted by complete change of ignition parts, apart from the coil. Contacts, condenser, rotor arm, distributor cap and plugs. I made a set of leads using a Sparkrite kit.

Two things:
1) The idle is rich. It becomes a bit lumpy when I fit the air filter housing with filter,
2) The normal running is very weak, where she will only pull if you pull the choke out.

The carb I replaced was a Zenith 361V and the new one fitted may be modelled on the same make and version but was intended for the 2.25 Petrol Landrover. The main and compensating jets have been swapped from the old one and these old sizes seem consistent with the Mk 1 manual.

I'm in a position wondering what to do. When I look this up, the original carb would have been a Motorcraft one. Without going the whole hog and the route of an ECU based injection system, is there another way forward?

[Mikexx]

I can't believe my luck.

A Motorcraft carburettor came up on eBay with the right model numbers.

It now runs well, where I have power and can even adjust tickover mixture screw with all the expected results.

[JustTrying]

Good to hear you sorted your problem. (First time on here in a while.)
Saw you were using an electric pump on your V4.
Thought I would just warn about having too high a capacity. Only needs to be around 3PSI and 25 litres per HOUR (some are rated in minutes).
If you fit a high pressure one, it can force past the needle valve in the float chamber.

[Mikexx]

Good to hear you sorted your problem. (First time on here in a while.)
Saw you were using an electric pump on your V4.
Thought I would just warn about having too high a capacity. Only needs to be around 3PSI and 25 litres per HOUR (some are rated in minutes).
If you fit a high pressure one, it can force past the needle valve in the float chamber.

Yes, I found the hard way some years ago.

The one I fitted seems to work ok without dribbling fuel into the venturi. I replaced the old pump that I felt obliged to fit a pressure gauge to and recorded some 9psi.