Weber DGV Advice Requested…

[Rocky_LC]

I’ve got a TVR 2500M.

It’s been converted over to a pair of DGV’s, on a Pierce manifold.

It runs pretty good when driving, but whenever I pull up to a stoplight, the car stalls. Also get a lot of backfiring when I let off the gas.

would like a little advice, I’m going to initially try to just pump up the idle a bit, but maybe there’s something I don’t understand about these guys. I haven’t really messed with them yet, only had the car for about a week.

I know there’s some Weber experts around here. Thanks.

Rocky

 

[Grantura_MKI]

Throw those in the bin and get some DCOEs.

 

[Rocky_LC]

Yep…. Sure is easy to spend someone else’s money... I was hoping the advice I would receive would be a little more “actionable”, and helpful…

I think the problem is a vacuum leak, I guess the carb bases are prone to warping, especially if overnighted, which these were.

Also found the main intake manifold needed to be snugged up. But I pulled the carbs, and am going through all the gaskets, and cleaning up the surfaces, and reinstalling.

We’ll see…

Rocky

 

[Grantura_MKI]

Penny wise pound foolish.
Just was helping you save your time and money before you learn for yourself.
I spend people’s money everyday on their cars doing a proper job!

 

[DrEntropy]

Rocky! You got ANOTHER one?!?!

You've been thru the DCOE's, a much better induction system than the DGV's, and we've found most available manifolds for 'em are a compromise. Fuel seems to condense and puddle at the bottom of those and makes for a no-start after the engine has been run to temp and let sit for longer than ten minutes. Cannon was the worst. Pierce has supposedly "engineered" theirs a bit better.

If you've cured all the vacuum leaks, played with the idle mix screws & throttle idle position, may be time to check basics like float levels.

And tho D was curt, I share his sentiment re: DGV Webers. You may get the engine to run acceptably with 'em, but it'll likely be: "that's about as good as it'll get" compromise, IMHO.

 

[Rocky_LC]

Yep, got another one…

This one is a very solid platform that has had a lot of “foundational” work done to it, uprights rebuilt, all new brakes, new steering rack, dynamat interior, etc.

Still needs body & paint and some electrical clean-up.

I’m in the evaluation process now, not sure if I will keep my Vixen or this one…

Anyway, lots of improvement with reworking the gasket interfaces, but I think the culprit is most likely the original intake gasket…

Rocky

 

[Grantura_MKI]

Which one to keep is a difficult question and really matters what you want out of the car.
Vixens where the last of the Turner chassis cars fitted with lighter bodywork. They are “drivers” cars and are nimble.
M‘s are the first of the Bagland chassis cars made up of both round and square tubes. The bodywork is much thicker and a heavier car that makes it more of a ”touring” car. They are much safer and upon crash testing at 30mph was able to drive away with very little damage.
I would keep the Vixen IMHO!

 

[Rocky_LC]

Honestly…. Having and driving both, I’m in agreement with you…

The 2500M maybe feels more “solid”, but the Vixen is more “raw”.

I was able to get out and really push the 2500M on some freeway cloverleafs, and onto the highway today, and it really put a smile on my face, but the Vixen really makes you feel like you are more connected, although perhaps a little less solidly due to a lighter chassis.

When you look at the chassis design, you can really see the structural upgrades that are incorporated into the 2500M.

 

[Grantura_MKI]

The designer of the chassis is Mr. Bagland…I consider him one of by friends. He is a top engineer who had a hovercraft business in the past and is a top sailor.

 

[JHaydon]

Rocky, I diagnose and "tune" Webers over the phone for a living. I am more familiar with DGVs than any other (though I've been forced to become very comfortable with DCOEs and I just learned about the DCN this morning as well).

The DGV is an extremely flexible and forgiving carburetor which was designed to provide good fuel mileage and around-town driving. DCOEs were designed for performance, and they certainly don't hide it.

Whichever you have, DON'T BIN THEM. Unless there is a major defect or damage, they WILL live and breathe again! Once they're back up to snuff, if you don't like their performance, sell them to put a small dent in the price of a set of DCOEs.

And before my fellow SU fans chime in... yes, I love SUs as well (now that I understand their brilliantly simple concept). And NO, I do not believe that any of them are inherently fussy, unreliable, bad, worthless, etc. There have been plenty of bad carb designs over the past century-plus, but they're not around any more. The really awful ones never even made it onto a production car. There are very good reasons why we're still talking about SU and Weber carbs in the era of cheap EFI -- and why the DGV and DCOE are both still available new from Weber. They work!

Based on your description, I'm going to ask you to first take a good look at the outside of both carbs and tell me if you notice anything missing. I have had an alarming number of customers describe very similar symptoms just before telling me that one of their idle jets fell out.

Feel free to PM me or call me at work (Pegasus Auto Racing Supplies tech line) if you want to take the conversation out of the public eye.

 

[Rocky_LC]

Thanks, JH -

Appreciate the support! These are Italian Weber DGVs, 1981 build (they both have an ‘81 date stamp on the bottom). They are not going into the trash bin, I know that.

I’m away from the car until tomorrow, but will reach out if I have questions! When I took them off, and cleaned them up, they seemed to be put together reasonably well, I didn’t notice any obvious issues on the exterior inspection….

 

[DrEntropy]

Nobody else (yet) has even mentioned SU's. Depression/demand carbs are indeed brilliant, set 'em up right once and they do just work. Reliability fell off a bit with Stromberg Zed-S versions tho.

The DGV was a "passenger car" induction system, good for de-tuned, production engines. They're "tuneable" within that confine, for sure.

In any case, a backfiring condition usually means an over-rich mixture, produced when after acceleration or mid-range RPM, the throttle blades are slammed shut and unburnt fuel is ignited in the exhaust system. Again I'd suggest a first look at the float settings.

My experience with DCOE's goes back to 1972, personal vehicles and customers' cars. Racing Alfa Romeo and Lotus cars as well. I'm fairly sure Grantura's experience is similar. We're not punters wearing Weber DCOE "bilnders". Just suggesting the 2500M's performance would better benefit with the DCOE's. Surely you will be able to dial in the DGV's to work acceptably.

My tuppence: Keep the Vixen! Send the 2500M on to another caregiver after you sort it. The Vixen can do the jitterbug, the 2500 does the waltz.

 

[billspohn]

I have no love for the DGV either but wouldn't suggest you go to DCOEs. It should be easy to find a stock TR6 intake and fit a pair of SUs to it (I'd avoid the Stromberg's, which lack easy adjustment, being smog carbs).

Or if you are a modifier, you could always shoot for a tricarb SU set up. This is one that I concocted for my MGC using later TR6 intakes (one and half of thm, cut and welded together to suit the MG head).

 

[Rocky_LC]

That looks good, Bill!

I’m having better performance now that I think got the vacuum leaks taken care of. Have had some other projects on the car (wiring up cooling fans) that have kept me from working the carbs as much as I’d like…

Thanks for the ideas!

 

[Rocky_LC]

So, after a bit of fettling got my idle problem under control, it appears!

I popped the top of each carb off, and cleaned out all the passages with carb cleaner. Pulled out all the jets, adjusted the float levels (Thanks, Jim!) and did another pass through the linkage.

I’ve got a nice, steady idle now.

I had stopped by a British Car specialist in Tallmadge, Ohio. He graciously gave me some of his time, and advice. Most things on the carbs were as they should have been…. my conclusion was clogged passage(s?) in the rear carb.

(He had deduced that the rear carb wasn’t providing fuel on the idle circuit, and that’s why I had to keep touching the gas (to get a pump shot as the RPMs were falling off…)

Anyway…. happy to report success…. Hopefully it may help somebody in the future. Thanks to all who provided guidance!

Rocky

 

[Rocky_LC]

P.S. I think Jake, who runs Foreign Car Specialties in Tallmadge, Ohio deserves a mention for taking time out of his day, and leading me down the path to a solution.

Many Thanks.

If you’re in the area, look him up. He’s got a great shop with a lot of cool cars in it.

101 South Ave.
Tallmadge, OH 44287

Foreign Car Specialties

 

[DrEntropy]

Pulled out all the jets, adjusted the float levels (Thanks, Jim!) and did another pass through the linkage.

So you considered posts #5 and #12 anecdotal? Tsk-tsk.

 

[Rocky_LC]

No, but I am always of the mindset of being as minimally intrusive as possible with each maintenance action.

I was able to address all the gaskets and linkage without opening the carbs…. When this was unsuccessful, I then took the next step.

In troubleshooting, I typically like to only change one thing at a time…
Rocky

 

[DrEntropy]

In troubleshooting, I typically like to only change one thing at a time…

Prudent.

 

[Tybalt]

Probably just as well that I've been out of pocket for the most part and missed this one earlier. Glad that things seem sorted at this point.