Weber: DFAV vs DGV

[mimregi]

I bought a Z with twin DGVs on it. I have toiled endlessly about ripping them out and going with SUs, but every time I almost do it, the cost has me wondering if I shouldn't just commit to what is there. The problem is that, as a guy who doesn't have much experience working on cars (yet... I'm learning and have decent instincts) the DGVs are a bit intimidating. Most of the info I can find assumes prior knowledge. The SUs on the other hand have a ton of accumulated knowledge easily accessible...

But you know that, and I digress.

I thought I might try to get a cheap, used DGV and play around with it so that I could learn it without risking my car being off the road for an extended period of time. I saw this:

http://cgi.ebay.ca/Carburetor-32-36-DFAV-23A-Weber-DGV-type-Pinto-Carb_W0QQitemZ260053905902QQihZ016QQcategoryZ33550QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

It's a DFAV and is currently at a nice, low bid. It looks pretty similar to the DGV. Anyone know enough about these carbs (and can point me at someone who does) to say if purchasing it as a project would teach me anything?

Thanks!

-m

[Arne]

I seem to recall that knowledgeable Weber people regard the DFAV carbs from Pintos much the same as Datsun SU people regard US-Flat-tops. So I really doubt that there is much to be learned from something like this that would be all that helpful. Although I should think you could buy it cheap!

But then again, as you know from earlier discussions on this, I'm definitely an SU fan...

[MAX]

Motor Sport Auto sells a couple books on Weber Carbs.....Although I haven't personally read them myself.....

Perhaps I should get them as I have a pair of DGVs on my 73 240Z. They work great except for a hesitation coming off idle which I can't seem to get worked out.

[mimregi]

This is really the single biggest thing I have wrestled with time and again. Thanks for the advice (as always) Arne, I'll probably pass on the DFAVs. I'm still poking around for an inexpensive DGV, but even at $100 (cheapest I have seen, and that's still a few days from selling) I'd be hard pressed not to just spend a little more and get an SU set-up in there. There's a promising looking auction for a very complete looking round-top set up available now, and I'm strongly tempted, my wallet is just dragging it's feet (I think I can make the money back by selling the DGVs, but that would be after christmas). Honestly if I could just find the level of information on the webers that is available for the SUs, that would make the decision all the asier, but I guess that's why they call it life =)

[Arne]

Honestly if I could just find the level of information on the webers that is available for the SUs, that would make the decision all the asier, but I guess that's why they call it life =)

I am also of the opinion that the Webers - once set up and jetted correctly - should work and drive fine. The problem is that those carbs were originally designed as a one-size-fits-all carb replacement for any number of different cars. Additionally, they weren't necessarily designed with multiple-carb use in mind. So getting them spot-on takes time and specialized knowledge.

The other part of this is that even if you get them running properly, they have a reputation (I have heard) for poor economy.

So my take on the Webers is simple - if you have a pair that are running well and you are happy with, keep them. But I personally can't see wasting any money on trying to fix a pair that aren't currently satisfactory since there are far simpler and well understood alternatives available.

[240ZMan]

Having owned SUs, DGVs, and now triple webers, I'll weigh in with a few thoughts:

- If your engine is stock and you plan to keep it that way, the SUs are the best solution. HOWEVER, most SUs are 30+ years of age and have worn throttle shafts which makes it impossible to properly tune the idle mixture. ZTherapy is a great way to go to solve that, but that's not cheap. Keep in mind that you may have to spend some additional $$$ on ebay SUs to get them into a reliable state.

- The DGVs give you separate idle and main circuits. If you're engine is not stock, this may be important as it was for me. I was not able to get the proper idle as well as part/full throttle mixtures with several sets of needles and nozzles. (I was using SU bodies rebuilt by ZTherapy.) The answer was going to be grinding my own needles. Instead I went with the DGVs and they were great. I was unable to feel any difference in power with them compared to the SUs: no more, no less. Because they have a separate idle jet, I was able to get the proper mixture at idle as well as at part/full throtle.

- If you are going to modify your engine for power, such as with a bigger cam and headers, then triple webers/mikunis is the way to go (assuming you don't want to switch to fuel injection). They are far more tuneable, albeit with an increase in the cost to experiment with the many jets and air corrector combinations.

In your case, it's hard to recommend a best path without knowing more about what your long term plans are for the car. I will say that after doing a rebuild of the DGVs, their low speed driveability was very much improved. They are not hard to dissassemble, especially since you don't have to remove all the linkage just to clean them. I bought a gallon can of the berryman's carb cleaner and once the tops and bottoms of the carbs were separated, I was able to fit them into the can to let them soak. Do one at a time so that if you forget how it goes back together, you have another one still in one piece as a reference. Of course, you'll have to decide if you're comfortable with this level of project, but I suspect that installing a rebuild kit after cleaning will solve most of your issues.

[MAX]

Hey Mimregi:

I'm still wrestling with my Weber DGVs as well. Here are a couple web sites that have some good technical information.

www.webercarbs.com

www.piercemanifolds.com

www.theautoist.com/weber_carb.htm

I hope this helps..

[mimregi]

Wow, thanks for the great info all. Just to add a few notes to keep this (very helpful to me) discussion moving:

-The car is running basically fin right now. I get the occasional plume of smoke, or hard starting, but it really runs well and has never left me stranded going on two years now.

-It isn't super powerful, and the gas mileage varies greatly depending on how I drive. While I would like to address those two things, the biggest thing that has me itching to do some cleanup is the smell. It can be downright awful. A few months back, I got a new exhaust installed and about the same time did a full tune up (points, cap, rotor, plugs,fuel filter, etc.) and the smell was almost non-existent. Already it is much more common and occasionally nose-piercingly strong. I don't think the carbs are fully at fault (and I have not yet even had a chance to look at the plugs), but I cannot shake the feeling that they could use some TLC. Certainly though, I am a novice and could be wrong-headed there.

-I don't know of any non-stock modifications to the engine, but knowing some of what I do about the car, I wouldn't be surprised. I'd love to dig in there some day and find out, but it is not on the short list of things to do. It is, by all external appearances, the stock engine for the car however.

-Funny that you mention EFI because I started thinking about that last night and wouldn't turn my nose up at some comments on that subject. I know that such a swap is large project (gas tank up, no?), but occasional large projects fit my lifestyle better than regular small projects. What should I expect to spend? Any gotchas I should consider before taking that kind of a plunge? I know lots of folks swap back to carbs from EFI and I assume that is for performance and tweakability, but with a standard setup, is there a notable performance loss?

The final thing related to that note and all of this really is that this is not a tweaker car for me. I have grand plans to do a ground up restore and maybe even a track racer some day when I have a house and a garage, but so long as we are in an apartment and the garage is cramped and money is an issue, those projects are in the future. For now, the '73 is my daily driver, so my primary motivations are reliability, efficiency and maintenance concerns (changing the oil every 6 weeks or so is one thing, but the thought of having to tinker with the carbs on a regular basis, which is maybe just my trepidation talking, is just impractical). Performance is an obvious secondary thought -- I didn't buy the car to go slow, but I don't need to win any races at the moment. I'm just happy I have a commuter I love so much -- this is my third Z and by far my best, I just want to take care of her right

Edit:

This was the first thread I looked at this morning... a quick peek around and I am already starting to talk myself out of the EFI thing -- still open-minded, but to do it properly (and I don't want a wirey, unreliable mess, that would completely defeat the purpose) it sounds like it may be expensive. Maybe if I can find someone looking to do a carb swap that wants the DGVs... still on the fence =/