Help with Carb

Arde

Arde

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Starting to look at why the car has a high warm idle. Weber 32/36.
Cold start works great, after warm up idle stays at 1500 or so. Restarting warm engine also stays at 1500. Don reported 1,2,3 plugs were fouled.

Picture 1 shows that when removing the air filter cover the area on top of the carb near the firewall has much more oily/dark residue than the other. Is that where 1,2,3 are?

Picture 2 shows that at rest the flaps of both carbs are not at an equal angle, the one near the firewall is partially open.

Picture 3 is a loose screw I found on top of the oil filter. What is it?

Anyway I wanted to warm it up and see the chokes in action but the battery died on me and until I recharged it it got dark.

What is the scoop here?
 

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Cylinder 6 is closest to the firewall. Cylinder 1 is closest to the radiator.

When was the last time you had them adjusted?
 
I think it's time for a tune up. The soot on the rear carb looks like it is getting more than it's fair share of blow-by from the valve cover pipe. This could be because the flap is more open, however if this pic is of a cold engine we'd need to see what if any changes to the flap occur when warmed up. Are the 1,2,3 plugs oil or gas fouled? If gas then you need to adjust the mixture. If oil then something else is going on but that would be unusual since there is no soot on the front carb which feeds 1,2,3 cylinders.

I'd clean up the carbs inside and out with a lot of carb spray, as well as the cover, until no more oil residue is on it. Check the operation of the choke flaps and adjust if necessary, at warm they should be straight up. Check that the linkage is not getting hung up on something and that the throttle plates return fully closed, there are stop screws for this also. There are also cold idle adjustment screws but those should be okay, more likely the cold idle linkage is stuck open, check that too.

Then once chokes are ok adjust each mixture screw for best idle by backing off the throttle screws equally till your idle is 700 or so then adjust the mixture screws till the highest idle. Go back and forth between the butterfly screws and mixture screws until you get to desired idle of 900rpm or so. A synchronmeter is really needed here to ensure both carbs are breathing equally, looking at the rear carb my hunch is that they are not.

The screw looks like a Weber style, check to see that you aren't missing one from one of your carbs. Check vacuum connections and gaskets for leaks.
 
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Those are Weber DGAVs, I have them on my car (for now), and that screw looks like it should be installed on the carbs somewhere. Given the you found it under the carb serving cylinders 1,2 and 3, it likely came off of that carb.

Its hard to tell the size of the screw without more perspective, but that looks like the screw that holds the cover on to the body of the carb.
 
What Steve said, although I'd start by making sure there aren't any vacuum leaks and then go from there. Nothing else matters if there's a vacuum leak somewhere...
 
Thanks for the tips.

The carbs were tuned up last November and were running great until February or so.
I suspected vacuum leaks and Don addressed that.
1,2,3 I recall were just rich mixture dirty not oil.
Maybe it is the loose screw.
Don is a fuel injection monk, he has garlic hung above the shop gates to repel carb ghosts.

There were so many experts at Legends... but it would have been bad form to stop the celebrations for a trivial loose screw...

It is me against dual carbs, I am outnumbered.
 
If that is indeed one of the screws that holds the top of the carb on, you will very likely have a vacuum leak.

Pull the air filter and look straight down on the top of the carb. Four of the screws are inset around the perimeter of the butterflies. The other two are located near the auto choke.

Compare the screw you found loose to these locations.
 
Ohmess said:
If that is indeed one of the screws that holds the top of the carb on, you will very likely have a vacuum leak.

Pull the air filter and look straight down on the top of the carb. Four of the screws are inset around the perimeter of the butterflies. The other two are located near the auto choke.

Compare the screw you found loose to these locations.
Click to expand...

The screw was smaller than the ones holding the top. See first picture.

Put some carb cleaner, started the car and warmed it up, see temp and idle at that time in second picture. The chokes were open at that point in the third picture so the close choke theory is wrong.

The wire connection in the fourth picture is not very healthy, what happens if that wire becomes an open circuit? Is that the electric choke?

Also I see that the front carb provides vacuum for the brake booster while the rear one has a tiny hose going somewhere, what is that hose and how come one carb does all the work for vacuum? Doesn't that create an imbalance right there?
 

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The wire is I think the idle cut off solenoid. The weber instructions always say most problems are caused by linkage.
However....
Your vacuum lines may be mixed up.
For your purposes of testing I might plug all the vacuum lines off the carb, at the carbs.
Including that line to the brake booster.

Than re-think the vacuum lines.

I have been wrong before, so wear your safety goggles, keep a fire extinguisher handy, no nearby incandescent bulbs during carb work, have your assistant stand in front of you and oh yeah, did I mention, take two aspirin, go to bed and call don in the morning.:smile:
 
I heard Don thinks all carbs are evil.

My brake booster setup is the same as yours; not likely to be your problem unless the hose, check valve or booster are leaking. The check valve is simple and cheap, you might check this.

On my car, the other vacuum hose was connected to a charcoal canister installed under the battery tray. Someone, I think Mario from VSR, informed me that my car did not originally have this hookup, so I removed it, plugged the outlet, and changed the routing on the canister hose.
 
You have water heated chokes so that wire appears to be the idle solenoid. If that goes open then fuel is cut off to that carburetor, it is designed to prevent run-on when the ignition is turned off. See if the wire connects to a unit that can be unscrewed from the carb base, or take a close up pic of where it attaches so we can see. Does the rear carb have it's solenoid connected - I can't tell from the pic.

The stock brake booster is fed from the front manifold so that is correct. Since theoretically it is a vacuum (unless the booster or hose is leaking), there is no imbalance between that and the rear carb. The corresponding rear manifold port is either blocked off or runs to the distributor for advance/retard functions. Trace the hose to see where it goes. It should not attach to the charcoal cannister, that would creat a huge vacuum leak, the cannister is attached to the air cleaner. There should also be other vacuum ports on the carbs, make sure they are either capped or run to the distributor. Report back on where they all go.

So if you have no vacuum leaks I suspect you have a linkage or adjustment problem. You'll need a synchronmeter with Weber adapter to verify the carbs are equal in their breathing.

You could have one or both carbs not where they should be in relation to the accel pedal stop or each other.

Synchronmeter (available from various sources):

http://www.ebay.com/itm/Weber-Dello...NEW-/271152160983?hash=item3f21eda0d7&vxp=mtr


Weber adapter:

http://www.ebay.com/itm/Weber-Carb-...aptor-STE40-Weber-32-36-DGV-DGS-/271800496845


This is a good thread for syncing carbs:

http://e9coupe.com/forum/showthread.php?t=15268


Once equipment is obtained I am happy to help via phone if you'd like. PM if so.


Not sure about the screw now, maybe an old clamp screw? You have now joined the DeQ thumb club.


Arde said:
The screw was smaller than the ones holding the top. See first picture.

Put some carb cleaner, started the car and warmed it up, see temp and idle at that time in second picture. The chokes were open at that point in the third picture so the close choke theory is wrong.

The wire connection in the fourth picture is not very healthy, what happens if that wire becomes an open circuit? Is that the electric choke?

Also I see that the front carb provides vacuum for the brake booster while the rear one has a tiny hose going somewhere, what is that hose and how come one carb does all the work for vacuum? Doesn't that create an imbalance right there?
Click to expand...
 
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Interesting.
pretty sure my brake vacuum comes off the intake MANIFOLD on the brake booster side of the car. Driver side.

my dizzy is t'd to the CARB bottom plate vacuum lines on the carb side of the carb/manifold engine. Passenger side.

I guess, for simplicity and more accurate testing, instead of plugging all the vacuum lines of the intake, one could just pull one at a time, plug it and see if your idle changes.

I am operating from memory though, and that is usually an issue. And by that I mean, you may be right and I maY be LESS right:mrgreen:
 
Yes that's what I meant, the manifold of the front carb. There are also ports on the carb itself. There are also ports on the manifolds for the EGR sysytem, these should also be capped if it has been removed, or a tube that connects them can be used as a balance tube.

restart said:
Interesting.
pretty sure my brake vacuum comes off the intake MANIFOLD on the brake booster side of the car. Driver side.
Click to expand...
 
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Yes, the weber manual says most problems are linkage related.
However, in this case...I might...
Plug all the carb holes. Disconnect the linkage at the carb and start from there. The modern redline linkage kits are tricky. Many places for binding.

That one carb is very BLACK. If you need to drive the car you should probly put a nice hose and clamps from the intake MANIFOLD port to the brakes.

I am feeling sheepish posting tech in a gruppe of experts. I hope you are not just baiting the new newbies to see what kind of idiotic suggestions we may come up with. Oh, did I say....I am not an expert but I play one on TV.:lol:

Your mileage may vary;-)YMMV hopefully your ignition is mostly close?
 
Oh this is not a bait post, I was lucky enough not to have to deal with carb issues in the last 10 years so I am truly getting up to speed on this.

The linkage theory does not explain why it only happens when the car warms up, does it?
 
No. I am hoping that eliminating vacuum problem is the beginning of the final solution.
I don't remember how we got to this vacuum diagnosis.
. If you still have that problem with all the vacuum lines plugged and the linkage disconnected at the ball joint near the carb....do you remember how to plug a vacuum line?
Than go back to step one.....check points still opening, plugs, check wires, set valves, change oil...blah, blah...

Those carbs are not that hard to get right if you are patient and follow the redline setup.
The linkage tuning also requires patience
http://www.redlineweber.com/html/Tech/carburetor_set_up_and_lean_best_.htm
Because that one carb is so black I thought the problem is near there.

Of course you are going to have to give it a tune up later but you probly want to have that high idle problem solved before you start doing a bunch of other things.

I feel a rambling blather coming on:shock:....

Sometimes if one goes ahead and does a bunch of minor things, minor problems can get compounded and confused. Who knows, maybe coincidentally a car has 3 plugs wire failure, a bad spark plug a stuck float, a pce of ****e in a jet and the valves need adjusting, the oil is wrong and filthy and flooded with gas from the car running so rich, points closed up, water in the crappy gas, air and fuel filter clogged, bottom of the gas tank has a gooey, half dissolved 3 foot piece of building tape and garden hose that fell in 2 years ago when a teenager was trying to siphon the gas....
If all that was happening one could probly be convinced that a new engine was required.:-P
 
So it is idling ok after it warms up?

When you first start the engine cold and you engage the chokes by pressing the pedal to the floor, what does it idle at while warming up until you release the high idle with a blip of the throttle once warm? Is this feature working?

Could be the cold start linkage.

Still good to have the meter to check everything with.

Where does the hose go from the rear manifold?
 
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