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My otherwise stock B18 is running a Weber 32/36 DGV. The engine idles beautifully when warm, but when cold it will die unless I keep my foot on the gas (and even then sometimes, esp. on cool mornings). Occasionally I get a backfire through the carb as well (again, only when cold). I've adjusted the idle and mixture several times according to the instructions, and the steady warm idle (right about 600 rpm) makes me think I've gotten that part right, at least. Is this a jetting issue, or is there something else I should be looking at?
TIA.
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The other Phil S. | '68 Amazon daily driver
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Thinking the problem might be a vacuum leak I sprayed carb cleaner and starter fluid all over the vacuum hoses, the brake booster, the flange where the carb connects to the intake manifold, and the exterior of the carb itself. No change in idle speed or smoothness, so I don't think it's that - unless there's somewhere else I should test for a vacuum leak.
As I mentioned in an earlier post, the choke linkage isn't closing the butterfly quite all the way, but fully closing it manually doesn't seem to make any difference. So my guess is it's not that either.
Anyone have any other ideas as to what could be causing this problem? Wild speculation and random guesses are welcome - I'm stumped.
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The other Phil S. | '68 Amazon daily driver
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Re "Other ideas", yes: After making sure your carb isn't clogged inside and is being fed with fresh fuel, try improving the strength and length of the spark at the plugs. Cold conditions and slow revs produce splattery, uneven, poorly evaporated air/fuel mixture into the cylinders. A long spark has a better chance of contacting a sufficiently rich and thus burnable mini-volume of mixture than a short spark does.
Temporarily try a spark gap on the wide side of 40 thousands and file the end of the ground electrode so it's got a sharp end crossing a flat-ended center electrode -- avoid roundedness where the spark jumps. Also check the high-voltage leads from coil to distributor and from there to plugs for not leaking. Looking at them in the dark with the engine running is a quick way; look for "lightning." Too little plug gap makes for cold idle misfire and sometimes at warm idle too. Too much plug gap first risks misfire under full load at medium and higher rpm, when the compression pressures are highest and resist the spark getting across the wide plug gap.
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is it a 32/36 DGV (manual choke) or DGAV ( water temp valve choke) or DGEV (elec choke) or a combo of A & E ? If it was an IPD kit it could be the combo.
FWIW, a new 32/36 DGEV is so cheap that replacment parts will come up to almost as much as a new one. Last time I checked the temp valve in the side of the carb body was $80, and an air choke element was another $30 or so, rebuild kit is $50, and a complete new DGEV is $149. But I' find a set of SU's if it was my 122.
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I agree. The cost of finding and rebuilding a pair of SU HS6s may seem like a lot, but it is undeniably worth every penny. I have had cars with the downdraft Webers, and have been disappointed with every one of them. They mask the quality of a B18/B20.
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1966 122s, 1968 142s, 1969 144s, 1979 245dl, 1989 244gl
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I suspect the problem is the electric choke not closing completely. CA car.
On the side note, I would like to have a pair of SU's, but then I would also need a new intake manifold to mount it on, followed by a new exhaust pipe. My header is a 4:1, I have no idea where it came from.
The Weber is fine for me, as I do not drive the car daily. It sometimes sits for a few weeks at a time in the driving months and I don't touch the car from Nov-Apr. The Weber is relatively maintenance free, but with the K&N air filter it is very noisy at full throttle.
Which reminds me, I need to put some washers on the throttle linkage. It rattles a lot above 3,000 rpm.
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My name is Klaus and I am a V♂lv♂holic
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Before I found my 3-carb 164 manifold I collected a few aluminum B18/20 intake manifolds.
Shall I send you one? I think it will work OK with your header.
I also have a bucket full of 2-bolt HS6 carbs I can make a pretty good deal on but they probably need refurbed. Since Jim Taylor died I have not dealt with the guy who took over his business but I could check him out if you like.
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George Downs Bartlesville, Oklahoma
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Thanks George, but I think I will let the next owner worry about 'restoration'. In the mean time I think I will just drive Xena and enjoy myself.
You thinking about going to South Dakota this year?
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My name is Klaus and I am a V♂lv♂holic
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May not be going to SD but probably will be going to the Gilmore, and my buddy Kent from SD
may go there also. Further plans may be made at that time.
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George Downs Bartlesville, Oklahoma
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My car is a California car, but has a manual choke nonetheless.
I'm with Klaus, though, in that I'm sticking with the Weber (so far) primarily for financial reasons. A rebuild on the original SUs, plus a new intake manifold and maybe linkage (the original linkage has disappeared, and I'm not sure how much of the Weber linkage can be adapted to the SUs) - we're talking substantial bucks. So for now I'm going to see if I can get the Weber to run properly.
And anyway, I just have a hunch that while the downdraft Webers might have their limitations, they're not junk - too many great engines have been built around Weber carbs for me to feel comfortable writing them off. I suspect that like any complex piece of machinery they need to be properly understood and tended in order to give their best. I'm just trying to figure out what "properly understood and tended" might mean. I have two books on the subject: Weber Carburetors, by Pat Braden, and the Haynes Weber Carburetor Manual. While I've learned a lot from both, neither one is of any help in addressing this problem.
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The other Phil S. | '68 Amazon daily driver
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It could be a few things now with some history info on what it's doing. There's a jet that is opened when the elevtric choke valve on the left side of the car is actuated, it doesn't just adjust the butterfly.
Last yr I took a Weber off my '71 145 that had among other problems a cold start issue, plus old gas was run through.
Anyway, since your car sat or sits over the winter old gas could be playing a role, and to a Weber old gas can wreak havoc and clog jets like the one I mentioned. In this tired old Weber the real problem was that the butterfly linkage was jambed into teh uppper housing that the pivot hole on each side elongated and wasn't resetting properly or wasn't adjusted correctly. I'm sure a annoyed right foot could have continued to make the issue worse by flooring it to get the Choke to re-set when it didn't.
The top carb casting was rediculosuly expensive. When I took it apart just about every jet was clogged or partialy clogged, ripped accelerator pump diaphram, really needed going through.
At this point either get a new Weber or at least a re-build kit.btw those 'Good' cars with Webers weren't these DGV series, most of them were side draft DCOE's a whole different animal.
I got a set of good cond SU HIF6 carbs and manifold and rebuilt them, best way to go.
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When the car is cold, take the air cleaner off and look to see if the choke butterfly is closed or partially closed. If your Weber has an electric choke and the butterfly is not sufficiently closed, the choke needs to be adjusted.
If your car has a manual choke, the butterfly should be completely open when the choke is not pulled, and mostly closed if the choke is pulled. If not, the choke needs to be adjusted.
Either way it sounds as if the choke is not properly enrichening the mixture when the engine is cold.
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1966 122s, 1968 142s, 1969 144s, 1979 245dl, 1989 244gl
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The butterfly is functioning as you describe. Apparently that's not the problem.
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The other Phil S. | '68 Amazon daily driver
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The rod connecting the choke to the idle cam can be bent into an "S" shape to give a faster idle speed.
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If it has a fast idle cam on it I would make sure the idle is increased when the choke is pulled.
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George Downs Bartlesville, Oklahoma
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George, it does have a fast idle cam, and idle increases when the choke is pulled - then decreases again after a minute or two, to the point where it dies altogether. I've read elsewhere that the increased idle is meant to be a temporary phenomenon, though I can't figure out how the duration is supposed to be controlled.
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The other Phil S. | '68 Amazon daily driver
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I have only had one of those carbs and only had it a very short time a LONG time ago but
I remember it as being trouble from the start. (a rusty gas tank was a major contributor.)
When it starts acting that way, is the fast idle cam still making the idle fast or has
something caused it to retract? (maybe an electrically operated choke?)
If so you should find out why it is doing that and see if you can adjust it to stay longer.
In other words keep the choke in operation until the engine is warmer.
CAVEAT!! This is totally guesswork on my part and NOT based on personal experience.
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George Downs Bartlesville, Oklahoma
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Hello,
I am pretty sure your major issue revolves around the lack of choke idle adjustment.
Both the electric choke and the water choke versions of the DGV have choke idle adjustment screws, but not the manual choke DGV.
On the manual choke DGV, the idle is raised by the eccentric that is part of the choke lever to which the choke cable inner wire is attached on the side of the carburetor.
When you pull on the choke, the choke lever on the side of the carburetor rotates causing the eccentric part of the choke lever to contact a pin that is part of a another lever that via a piece of linkage will open the throttle flap via the throttle shaft linkage to raise the idle.
There is usually a decent sized gap between the eccentric and the pin, plus there is usually some excess play in the rest of the linkage which results in very little idle change when the choke is pulled.
To add some adjust-ability to the choke idle, we use a slice of a Teflon rod.
Before we cut a slice, we drill a hole intentionally off center.
It is important that the hole is just large enough to fit tightly on the pin so the slice does not rotate when the choke is pulled.
We then push the slice of Teflon onto the pin and with the hole drilled off center you can rotate the slice to adjust the amount of choke idle.
I am sorry, but I do not know the diameter of the Teflon rod nor the size of the hole from memory, but I will try to post the sizes when I get back to work.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
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Okay. Took a close look at the operation of the choke and associated linkage bits this morning. Turns out that pulling the choke cable all the way out doesn't cause the butterfly to close completely. Aha! thinks I, I will close it completely manually and it will run beautifully, even when cold. Alas. No such luck. Same crappy cold idle, foot on floor to make it rev up at stoplight. Grrr.
When I parked it a few minutes later (after climbing a very steep and long hill, so engine was fully warm), I was greeted by a whistling sound that tapered off (quickly) when I shut down. Sounded like a vacuum leak to me. But - and here's the question - could the vacuum leak be contributing to the crummy idle only when cold? I can imagine a vacuum leak making trouble for the idle, but I would expect it to be a problem regardless of engine temperature. In my case it idles great when warm.
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The other Phil S. | '68 Amazon daily driver
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Thanks for this, Eric. I think you've probably nailed it - though I can't say for sure that I can visualize exactly what you're describing. I'll take another look after a cup of coffee.
But it bothers me is that this fix should be required. Seems like the &$*&# thing should have been engineered better. I might have to temper my statement that the Weber DGV can't really be the piece of junk others have called it.
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The other Phil S. | '68 Amazon daily driver
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Hello,
I can't remember, manual or electric choke?
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
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Hi Eric.
It's a DGV, i.e. manual choke.
Phil
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The other Phil S. | '68 Amazon daily driver
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