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MGB A little different DGV installation...

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Joe Reed

Joe Reed

Jedi Warrior
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Just thought I'd share this here in case any other DGV users (or those contemplating using one) might be interested...

Although I normally run a DCOE I do have a DGV setup I've run for a short time once before. Having a couple of things I want to change on my DCOE setup, I need to install the DGV so I can continue to drive the car while the DCOE is on the workbench.

I did have a couple of things I wanted to do to the DGV first:
- I never liked the awkward position of the mixture screw on the side toward the engine
- The linkage on the carb would not allow the throttle to fully open! This is an issue I've seen on other DGVs as well

The solution? Mount the carb 180 degrees from the norm....and rework the linkage. Reversing the carb accomplishes a couple of things.
- Puts the mixture screw on the side next to the wing so it's easy to see and reach
- Moves the fuel line connection away from the engine and exhaust manifold heat

The only issue with reversing the carb on this manifold was that I had to open up the top of the manifold a bit since the 36mm choke was now on the opposite side of the manifold and would have been partially shrouded by the manifold. A few minutes with the Dremel solved that.

I fixed the linkage issue by mounting a bracket to the bottom of the manifold to hold the part of the old linkage that let the cable turn 90 degrees. That also provides a place to attach the return spring. I made sure the new bracket changed the geometry to allow WOT at the cable's maximum pull.

Just for kicks, I also decided to fashion a heat shield. Don't know if it's really necessary but, when I ran this carb several years ago, I did get some hard starting issues when trying to restart immediately after a long drive....an issue that seemed to be directly related to heat soak after a hot shut down. The heat shield was cut from a piece of 22 gauge steel and the bottom side covered with some self adhesive Thermo Shield material.

Maybe I can install it this weekend and see how it works. First I have to go to a bicycle shop and get a new throttle cable :smile:

DGV_front.jpg

DGV_rear.jpg

Throttle.jpg
 
Thanks, Joe! I've always thought that Webers often get a bum rap, given the, ummm "heated" discussions over them. I'm looking forward to seeing how your modifications work.

Mickey
 
Joe,
I've made your post an article in our "Articles" section. If you click on Articles in the upper Navigation menu you will see your post now listed as an article.

Basil
 
Mickey Richaud said:
Thanks, Joe! I've always thought that Webers often get a bum rap, given the, ummm "heated" discussions over them. I'm looking forward to seeing how your modifications work.

Mickey
Click to expand...

It funny that so many people love their Weber carbs, but so many others have such disdain for them. I'd never say they were better than a pair of SUs but they're a good alternative for ditching the ZS carb. I've run both the DCOE and the DGV. They both perform well on my car....but I've always preferred the better low end throttle response of the DCOE. At WOT acceleration I doubt there is any difference, but I'd always be giving the DGV more throttle accelerating at lower speeds that I do the DCOE - which isn't surprising given the progressive nature of the DGV. That's almost certainly why I didn't get any better MPG with the DGV :smile:
 
Basil said:
Joe,
I've made your post an article in our "Articles" section. If you click on Articles in the upper Navigation menu you will see your post now listed as an article.

Basil
Click to expand...

Hopefully I'll have an update to add in a few days...
 
From my experience the DGV version is not the culprit with hard start after a "heat soak". Rather the design of the manifold it sits on. The DGV, being a downdraught, usually sits on a Cannon manifold and the issue comes due to raw fuel pooling directly under the carb after a shutdown. The condition is exacerbated as fuel in the bowl expands and seeps down into the manifold. On restart the machine essentially "floods" and takes a bit more cranking to clear the overfeed of fuel. The DCOE manifold is rather a short run and straight into the intake, no "reservoir" to allow raw gas to pool into and the DCOE is a bit further away from the exhaust manifold with less chance of fuel expanding to leak into the intake runners. The heat shield should help alleviate DGV hard start issues after the engine has gone to normal operating temps. We will be interested in the results. Thanks, Joe!

Most folk who diss Webers are mystified by 'em, thinking they are too complex. Truth being; once the DCOE is set up to the engine it's mounted on they are reliable as a house brick. The only engine in our little stable NOT running DCOE's is Diesela and if I could figure how to mount a set of 'em on a five banger and meter fuel to a diesel, she'd be fitted with 'em as well. :smirk:
 
DrEntropy said:
From my experience the DGV version is not the culprit with hard start after a "heat soak". Rather the design of the manifold it sits on. The DGV, being a downdraught, usually sits on a Cannon manifold and the issue comes due to raw fuel pooling directly under the carb after a shutdown. The condition is exacerbated as fuel in the bowl expands and seeps down into the manifold. On restart the machine essentially "floods" and takes a bit more cranking to clear the overfeed of fuel. The DCOE manifold is rather a short run and straight into the intake, no "reservoir" to allow raw gas to pool into and the DCOE is a bit further away from the exhaust manifold with less chance of fuel expanding to leak into the intake runners. The heat shield should help alleviate DGV hard start issues after the engine has gone to normal operating temps. We will be interested in the results. Thanks, Joe!

Most folk who diss Webers are mystified by 'em, thinking they are too complex. Truth being; once the DCOE is set up to the engine it's mounted on they are reliable as a house brick. The only engine in our little stable NOT running DCOE's is Diesela and if I could figure how to mount a set of 'em on a five banger and meter fuel to a diesel, she'd be fitted with 'em as well. :smirk:
Click to expand...

And I've found that condition worse when using fuel that is 10% ethanol. When I've been able to find ethanol-free gas the problem is pretty much alleviated.
 
Yup. Higher volatility.
 
Finally got around to installing the DGV today. The reconfigured linkage works perfectly. Now I just have to get used to driving it! It's interesting how differently the car "feels" with the different carb. Part of that is that the DGV has a stiffer return spring that the one on my DCOE. The DGV is quieter...and feels different at lower speeds around town - which is expected since the engine is breathing through a single throat instead of the twin 34mm chokes of the DCOE.

I like the changed setup on the DGV....it makes for a cleaner look. The fuel line enters the carb from the left rear instead of the right front, so the fuel line doesn't have to wrap all the way around the front. The throttle cable is pretty much invisible since it runs low on the left side (and the cable housing from the bike shop has the brand printed on it - "Jagwire" :D ). The hose I have running from the tappet cover to the air cleaner is a short run next to the valve cover. Over all, a much neater install.

Now that the DCOE is on the bench I have to find time to play with it. Then I'll have to decide if I want to continue to run the DGV....or get used to the DCOE again!
 
I had a 79 once with a Weber DVG on it and the only minor problem I ever had was a hesitation when stepping on the gas. Changed jets, timing, regular and high octane gas but never could get it to go away. It was on the car when I sold it. I only run SUs now. PJ
 
I guess I'm lucky, but I don't have that hesitation that seems to be so common. I do have to use a little more throttle when pulling from a stop...but then I've been driving with the DCOE so long - and it's feeding through two 34mm chokes instead of just the single primary throat of the DGV.
 
It worked fine for the short time I used it - which was only a week or so. I refinished my DCOE carb and manifold and switched back to it. I've always preferred the DCOE anyway, so that was the plan all along. I just got it done quicker than I thought I would...
 
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