Lotus Elan

Help with Webers

PostPost by: oldchieft » Sun Apr 27, 2014 9:34 pm

Hi all
I have a running engine after the fire rebuild, but the carbs are a bit of a mess.

The fuel levels are wrong, one too high and one to low. I have tried the acrylic rod but my eyes are not as good as they once were, or my method is faulty.

The throttles are not closing evenly, when one is seated in the bore I can still get feeler under the other.

I am sure I am pulling air into the engine, one of the exhausts gets cherry red very quickly! So a good coat of looking at needs to be applied.


I will pull them off in a day or so and renew the bearings, and have another shot at the setting the levels on the bench.

The cork seals on the shafts seem a poor idea to me, does anyone know any reason not to use sealed bearings?

I am also minded to ease the fit of the screws in the butterflies with a file to enable them to centre and seat evenly in the bores, is the any reason not to do this?

Advice from those who have been there would be appreciated.

Jon the Chief
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PostPost by: mbell » Mon Apr 28, 2014 12:29 am

I think you can check the fuel level with printer paper. Cut a thin strip and slide it down the in place of the jet. You can see if the paper has come in contact with the fuel. You should be able to compare levels with this method and if you know the right depth also set the fuel level.

I also had problems with uneven gaps on the throttle plates. One was sealing closed and one was quite far open.

I think the holes in the plates are designed to make the plates adjustable. So I adjusted mine to try close up the gaps. Then adjusted the the link so they had a similar gap around them, they need a little bit of a gap so the engine can breath at idle.

Haven't fitted them back on the car yet so not sure if I've sorted them or not.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: rgh0 » Mon Apr 28, 2014 12:42 am

The earlier Webers had leather seals I am not sure what the more modern ones use. I would retain a seal even if I used sealed bearings as bearing seals are not really designed to hold against the manifold vacuum.

The gap in one plate may be due to the carb shaft being twisted slightly in which case you can gently tweak it back so both plates are parallel.

cheers
Rohan
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PostPost by: oldchieft » Sun Oct 05, 2014 7:13 pm

Time has slipped by and other things have pushed this job to the back burner, but at last I have got back to the carbs.

I have had several shots at setting the level on the car and found it next to impossible.

The man who seems to be the go to guy on this subject is Keith D. Franck.

In his white paper he says "Ideally, this should be done while the engine is idling and level."

My guess is this would be to have the float operating under "live conditions" of flow in and out via the idle system.

To get to a situations where I was not pressured while doing this job I have made a rig to do this job with the carb removed from the car and with the desired flow conditions.

First I made a bottom cover with a drain valve to give a simulation of a running engine.

IMG_1341.jpg and
Drain connection


Then a rig to give the same angle as the mounting on engine. (in my case 2 degrees back slope)
IMG_1339.jpg and
test rig


This is then fitted with a feed from a SU pump from a can and a drain back to the can.

After that I was able to mess with the top cover at my leisure and at last got the acrylic rod to work, but found that a screwdriver with a o ring on it worked better.

It still took a while to get it spot on but it was a fairly stress free job this way. Not many would be inclined to mess about like this but if others are finding this a difficulty they might like to try this way.

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PostPost by: mbell » Mon Oct 06, 2014 3:04 am

As I have an elec pump on my car, I just turn the ignition on and left the pump fill the carbs. Turn off and then check the level. I assume that the fuel in and out of the carb will be balanced enough to not need to simulate it.

I tried the paper trick on mine but didn't really work. So I put a pointy screw driver down that is marked at 25mm, if you look carefully you can see when the point hits the fuel in the jet holder and see if the 25mm mark is above, below or at the top of the jet holder. Simple, quick and not too tricky.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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