Removing the Webers

[bitsobrits]

No. There are no additional ports in the inlet tracts as standard, excepting of course the port on the front tract for headlamp vacuum.

I use a Unisyn flow gauge which you hold over each air horn, in turn, to use. There are other similar gauges out there.

[billwill]

No most WEBERs do not have balancing ports. The Dellortos do.

[111Robin]

Previous owner has added ports to the inlets on my car, presumably to assist with balancing.

[ajwheels]

No most WEBERs do not have balancing ports. The Dellortos do.

If by chance you have Type 151 Webers, there are balancing ports just down-stream of the throttle plates.....works real nice with a Carbtune device, monitoring all 4 throats at once with airbox in place.....

[Fourducs]

My Webers are type 31. I briefly considered drilling and tapping some ports, but decided it will be much easier to get familiar with another type of meter. So I have another meter ordered. Thanks for the advice lads.

[Fourducs]

After discovering a leaking fuel tank in "Plus 2" I replaced the fuel tank, blew out the main fuel line, flushed out but did not pull the fuel pump, and pumped fresh fuel through the fuel lines to the carbs. The gas appeared to be clean. I pulled the carbs to get to the fuel pump, but after studying some videos decided not to rebuild them yet. Instead, I inspected and cleaned the things easy to get to i.e. several jets, the fuel strainers, and the fuel in the float bowls. The fuel in the float bowls was indeed dirty and I suctioned it out. Put everything back together. She cranked and idled just like before. Took her for a short drive in the neighborhood and she seemed to run smoothly albeit with little power at the low revs I was using. Then I decided to synch the carbs and take her for a test ride before deciding whether to pursue rebuilding the carbs.

I did my best to synch the carbs per the manual and adjusted all four idle mixture screws in the process. Took her for a test ride and she failed miserably. Although she cranks fine and idles fine, she spits and sputters so much I was not comfortable driving her around the neighborhood, much less a real test drive.

Is my next move is to set all the mixture screws at ¾ turn open and see what I have? All the snap, crackle, and pop makes me also wonder if I have some air leaks. I sprayed carb cleaner around the manifold o-rings to see if the idle changed. Not sure how else to check for leaks there? I did violate the gasket on both carbs that seals the top of the float bowl, but I “think” the gaskets are still serviceable.

Being intimidated by new mechanical challenges I want to ask this forum for thoughts before I order carb rebuild kits and start fresh with rebuilding the carbs. The fact that she ran smooth for a very short ride before I fiddled with the carb settings points me back to what I changed. That seems more likely than air leaks, or some fresh contamination having worked its way into the jets. #2305, non federal, LHD 1969 Elan +2 Weber 40 DCOE 31

[SENC]

The fact that she ran smooth for a very short ride before I fiddled with the carb settings points me back to what I changed.

Did you state what you changed - I may have missed that?

Before diving too deep into the carburetors, I'd confirm everything is right on the ignition side - timing, spark, etc. Once confident you have a good spark at the right time on each cylinder, you can move onto the carbs.

What jets did you find when you opened it up (idle jets, e-tubes, main fuel jets, main air jets)?

Are your idle mixture adjustment screws the early blunter version, or the later more tapered version (this determines how many turns might be a good starting point)?

Assuming ignition is right and jets are appropriate, the starting point for the idle speed screw is 1 turn from where the throttle first starts to move. This will open the butterflies enough to get idle, and as you get mixture and timing tweaked you should expect to turn this screw back a bit - ie., you should end up with this screw at <1 turn from contact. Blunt idle mixture screws can initially be set at 3/4 to 1 turn open - sharper IMS can be initially set to 1-1/2 to 2 turns.

It is also worth checking your fuel level in both carbs. Remove 1 or both e-tubes from both carbs, replace the cap, and idle the engine for a few seconds to allow the wells to fill. Remove the cap and use a caliper or even a stick to measure fuel level - you're measuring from the surface of the fuel in the well to the top of the well (not to the carb cover).

[Fourducs]

What I changed between a short smooth test run and all the misfiring was the idle mixture settings on all four throats. Of course, I also changed the throttle coupling screw and the idle speed screw on the rear carb when I was synching the carbs. I do not know what jets I have or even if I have the blunt or more tapered idle mixture screws. Will dive in and see what I have. Also I will check the fuel level in both carbs. Additionally there is still the possibility of fuel contamination clogging something up so I will look for that also.

I realize proper timing of plug firing is the starting point, but I don't see how what I did to the carbs could have changed the timing. This car was converted to electronic ignition by the prior owner so timing seems to me to be less likely to be the culprit. I will take a look at the plugs and spark.

Thanks for the advice.

[billwill]

I always reckon, that it is best to get the idle mixture right (or near right) first by using one of those transparent spark plugs (ColorTune). It enables you to SEE the colour of the internal flame.


Well worth the money.
https://www.google.com/search?q=transparent+spark+plug

https://www.google.com/search?q=colortu ... nt=gws-wiz

[Craven]

Leaking ‘O’ rings can cause a lot more problems than you may think, even new rings can take time to completely bed in. Any changes in engine speed when carbs are gently rocked indicate an air leak.
FWIW

[mbell]

When does it miss fire? At low rpm? At high rpm? When opening the throttle or with steady throttle?

Webbers have multiple ways of providing fuel at different times. So important to understand when the issues occurs to understand where to look.

[Fourducs]

She misfires at low rpms when opening the throttle. Not at idle. This behavior makes me suspect the progression circuit. Is this thinking correct?

[Quart Meg Miles]

I always reckon, that it is best to get the idle mixture right (or near right) first by using one of those transparent spark plugs (ColorTune). It enables you to SEE the colour of the internal flame.

Well worth the money.

Absolutely! I couldn't hot-start my S130 years ago until I used one and never had a problem after that. I'm tempted to by a set of four (about 100 UK pds) but Paddy told me his (tuned) S1 wouldn't run with four fitted.

On the vacuum gauge matter I bought a quad pack from a bike dealer for 50 UK pds for my 151 pair but previously I had drilled and tapped my inlet manifolds for the purpose but have now sealed them.

[SENC]

Does this happen with a long, slow acceleration or with a quick stomp on the accelerator, or both? Only under load or the same issue if just revving in neutral?

I've been learning Webers on my Seven, and have found there are so many variables it can be difficult to know exactly where to tweak. My ask about the jets you have in is two-fold in purpose - 1, to make sure they match (I found a mismatched set in mine, perhaps to overcome an issue that existed?); and 2 to understand your starting point (others here with Webers on Elans can better help there).

In addition to the idle jets, vacuum, air leaks, the butterflies and their position relative to each other and relative to the progression holes can impact the transition.

Pull the idle jets and inspect them. Remove the progression hole covers and the idle mixture screws. Put a couple small flashlights in the carb throats and look at the progression holes while the butterflies are fully closed, then use the idle speed screw and watch the progression holes. You should be able to see as the butterflies uncover the holes - if unequal within a carb, you may have a twisted throttle shaft - if unequal carb to carb, you have balance issue between the 2 carbs. With the butterflies held open, you should see light in the idle mixture screw cavity. While all this is removed, with use some carb cleaner (with spray straw) to spray directly into each idle mixture circuit in the outside of the idle jet cavity - you should see free flow through the progression hole cavity and into the idle mixture screw cavity. This will confirm the idle circuits from jet to screw are not clogged.

Fuel level is also important, so check that in both carbs after idling and while you have the jet cap off.

With these checks complete and additional information and maybe a few pictures provided, you'll probably get better guidance.

[Fourducs]

The acceleration misfire was with a slow linear use of the throttle, not a stomp of the throttle so I do not suspect the accelerator pumps.

Have not checked for misfiring when revving in neutral. If it runs smooth while revving slowly in neutral what does that indicate vs. misfiring under load?

Never thought about the flashlight method of checking the progression circuits. That particularly catches my attention because I did try to twist the throttle shafts in order to balance the vacuum in the throats on the same carb.
Will definitely check this as well.

You guys have given me some really good feedback on stuff to check. Thanks very much to all.