Weber DGAV - Single Progressive Jetting

[mr914]

I have a '71 914 that I recently fitted with a 2.0 from a 73.

I have the Weber DGAV carb that I have transferred over from the previous 1.8.

Can anyone tell me what the proper jets/emulstion tubes/idle jets are for a 2.0?

Thank you.

BTW.
'71 914-4
2.0
M-Strut conversion
Koni Yellows
22mm Gundrilled tortion bars
180# springs
7" fuchs
rear 5 bolt conversion
Side Shifter
Chasis stiffening kit
Reinforced trailing arms
SS Brake Lines
19mm Master Cyl
Turbo Tie Rod Ends

[Dave at Pelican Parts]

I don't have jetting suggestions for you. Actually, I think you should remove the "Pinto Weber" from your motor, and throw it as hard as you can. Get some duals, 40s or 44s on a 2.0 would work nicely.

The single-carb setup is rather sub-optimal on a Type IV engine...

--DD

[red-beard]

Dave,

I understand the sentiment about the 2 barrel carb, but....

From a starting, and "daily driver" standpoint, these 2 barrel carbs should be almost superior to the 40's. And to really get anything out of a set of dual 40's you need to change the cam.

(My god! Blasphemy). I think the problem is that the applications have been on sub-optimal cars and engines. These are not that different from the single center carb on the bugs (Which are smaller and good to about 70 HP). They are cheap and easy to implement, so some one with bad FI, little or no mechanical skill and a cheesy car could go for this. These are definitely the carbs you find when the car is a "low end" model.

A 2 barrel carb with an electric choke should make for a decent starting and around towner. The Weber 32/36 DGEV is not that different from the 2 barrel carb on my Toyota Celica (20 R) from the mid 70's. And it was about 110-120 HP.

I have 2 cars with this setup (no I'm not proud). I am planning FI for one and 40mm Webs for the other. But I was also thinking about dual Weber 32/36 DGEV progressives on one, as an experiment. Do I think you leave HP on the table with one of these setups? Probably at max throttle. But a progressive 2bbl carb should run more smoothly at startup, lower air flows and part throttle conditions.

Let me do some experimenting around with a single and a dual setup and I'll report out in the next few weeks.

OK, back to the original poster. While the 32/36DGEV has some changeable parts, I think you're going to find that with the proper tuning, it will run fine as is. If you don't have the tuning directions, most the Weber carb places have them:

http://www.webercarburetors.com/PDF/webertechcatalog.pdf

Make sure you get new intake gaskets and that your studs are good. You need to be able to make good vacuum for these things to work right - no leaks! Also, the VW "rubbers" usually go bad after a while. I found that Homedepot has a rubber connector in the plumbing isle that is a decent replacement.

James

[Dave at Pelican Parts]

James, there's a small difference. The Type I installation was designed to have a single carb. The Type IV was not. Now, if you can put a "heat riser" onto the 914 exhaust so you can heat up the carb, you can get it to be more reasonable. But unless you do that (or adapt an electrical heater from something else, possibly an old S-10?) it won't work that well...

The heat will help to atomize the fuel and keep it in suspension. With the long unheated manifolds of the Type IV, it will tend to drop out and wet down the walls. That leads to poor combustion, and mediocre driveability. The duals should actually offer better driveability if they're tuned decently. The manifolds for those are short, and the carbs are right over the heads which will heat them up decently. That will tend to keep the fuel in suspension much better, and offer better driveability.

Then again, for a stock motor the stock FI is far better anyway.

But hey, it's your car...

--DD

[red-beard]

Didn't the Bus engine use a single carb? And the 914/4's in Europe? Anyone know the 914/4 carb setup in Europe?

Grusse? You listening?

Dave: I agree, FI for a stock motor is best!

James

[JWest]

The factory carbed Type 4 engines used dual single barrels (bus and 914).

I think you will find dual progressives to be a bad choice. Many years ago there were actually kits for this on Type 1 motors. The problem is, a SINGLE progressive is sized correctly for our motors. The total CFM for two IDFs seems to be way too large, but the reversion cased by having independent runners makes a much larger carb necessary. This is why a single 40 IDF (in the center) and dual 40 IDFs are BOTH the correct size for a VW motor - the manifolding changes the way the air flows.

If you run dual progressives, you can't run an IR setup, and you end up with a 32mm AND a 36mm throat per two cylinders. A single 40mm throat is more correct for a "per two cylinder" siamezed manifold. That is, if you have more than about a 40mm size for dual single barrels (or dual progressives) you will be overcarbed.

I hope that makes sense.

OT: Grusse is a German greeting - his name is Roland Kunz - this was brought up another time when someone else was confusing it also.

James to James

[karlp]

I have a feeling the unheated manifold of the single progressive is not that big a problem. It does not get that cold around here (Lower Alabama), but I have driven when it was in the high 20's with little trouble. If I drive 5-10 minutes, and stop for coffee on the way to work or whatever as I usually do, and then go, it runs just fine. If I just keep driving, it will be sluggish and hesitant for 15-20 minutes. No problem at all in the summer.

Of course, I've never driven a 914 with FI or any other induction, so all I know is what I got, but it runs pretty good.

RedBeard makes an interesting point; I would like to see how a pair of the Super Pinto Style Racing Two Barrel Progressives would work. It seems like mine is gasping for air at ~4500. It makes no sense to go any higher. The duel progressives would also require much shorter manifolds.

I had a type I (Ghia) that I believe had pretty much the same carb. It reacted to cold weather about the same. It did not have heated intake manifolds.

Hope I don't get my &ss chewed, this is just what I have experienced.

[JWest]

I think the preheat is more important for cold running when icing can occur rather than cold startup (you've got mixture enrichment to make up for that anyway, and you can add more to compensate for bad distribution to some extent. The VW bug engine has the carb well above the motor and can ice up the manifold at high speed low thottle opening (highway cruise). I've had it happen so I know.

I don't think this would be as much of a problem with the type 4 because the intake is much closer to the hot engine and the intake has more volume so the air is does not remain at such high speed (four runners vs. two on a bug). My concern with the type 4 progressive is mixture distibution. The idle port is at one end of the carb and will feed cylinders 1 and 3 but less to 2 and 4. The distribution is similarly out of whack for the rest of the range of the carb. On the primary circuit 1 and 3 will be rich and 2 and 4 will be lean, while once the secondary comes open the opposite is true. None of this matters too much for a mild, lightly loaded engine, but it is definitely not optimal. This could be cured with a different manifold design, but is it worth it?

Bottom line? Fuel injection is better

James

[red-beard]

But what if I put a Tornado on it?





I sort of brought up the point as a discussion issue. The Progressives are definitely sub-optimal for maximizing HP. But, a properly setup, choked and winter heated progressive should make for an easy daily driver.

I guess what I really need to do is...before I re-install FI on my 1971, 1.7...is buy a little dyno time and really see what it's doing.

Who has an "At the wheels" dyno in San Diego?

James

[Dave at Pelican Parts]

I think you'll need more than just "winter" heating.

Look at how the Bug driveability suffers when you block off the heat riser that goes to the carb. The Type IV is no different, even though the velocity through the intake runner pipes may be lower.

BTW, the carbs drop the temperature of the incoming air on their own. It takes heat for the fuel to evaporate, which the carb is trying to accomplish. This can easily drop the temperature in the venturi and at the jets by a good amount.

If you run a single, find a way to heat it. Otherwise, duals are the way to go with carbs.

--DD

[mr914]

I have been using the single DGAV setup for the past 12 years on several motors/914's. It's not as pretty as the duals but I infrequently have any problems with it. I'm pretty much a 3 season driver - NO WINTERS...

I upgraded to the 2.0 motor last year. And don't have any notes for the 2.0.

The link in the previous post was interesting, but gives not information regarding Main and Idle Jets, Emulstion tubes and air correction jets for both primary and secondary sides.

The other information I had gotten out of a 20 year old "redline" book. The person that had it is long gone, have not seen him in 15 years...

I did find the following link http://www.redlineweber.com/ It has more information but no information on jetting.


One of these days, I'll find a set of 2.0 FI parts for the right price and put them on.

I've got plenty of 1.7 and 1.8 FI parts to trade.

I know that the FI computer and Distributor from a 73 1.7 is the same as a 2.0. I need the fuel rails, injectors and plentum.

Thanks for the help!

[mr914]

Found this site that talks about the conversion and has some good pics..

http://www.boognish.org.uk/car/carbconv.html

[anthony]

For 1.7L and 2.0L fuel injection compatibility you can check Brad's (pbanders) web site:

http://members.rennlist.com/pbanders/DJetParts.htm

Off the top of my head you'll need a 2.0L MPS and matching ECU or at least units that are compatible. You need 2L injectors (1.7 injectors are different.). The distributor on the 2L engine has a different advance curve but by all accounts a 1.7 dizzy will work. In any case, check Brad's compatibility table.

[mr914]

Looks like the 73 FI computer and Dizzy are the same part number for both 1.7 and 2.0.


Anyone come up with jet sizing?

[red-beard]

Actually, I just ordered a jetting kit from a weber place.

http://www.carbs.net/Weber/weberpartscarb.asp

James

[mr914]

When you get your kit. Would you post what Main/air/idle jets you recieved and where they go? Also, does the kit include the emulsion tubes?

I've got scads of jets/emulsion tubes. Thanks to an import yard that was going to send a number of cars/parts to the crusher. "Hey guys, I'll give you $20 and a 6-pack to let me take some misc parts out of the cars...."

I was trying to jet the carb for a super-vee spec motor that I had built at the time...

10.1:1 compression
Ballance to .3 grams
Polished rods
modified crank
lightened flywheel
big valve heads - port and polish
dual valve springs - SS Valves
hd oil pump

Lasted about 30 hours. But, wow, was it fun

Good thing I was only using it for DE events. That 30 hours equated to about 2 1/2 years.

When I built it, I knew it was going to only last 30-40 hours untill freshining. And that the heads were going to be trashed after 100 hours.

It ran like a rotary, no torque curve, would twist out to 7,800 rpm.



And yes, it ran a DGEV!!!

Just had to drive it like a turbo, keep the foot on the throttle to keep the air flow up.

[philinjax]

I had a Weber progressive 2 bbl carb on my 1.7L yellow car back in 99. It ran very well, far as I could tell. In 2000, I bought a set of Webber 40IDF carbs. and I thought, now I will get a big kick in power. No deal, I jetted it correctly, I think, and it also ran very well but there seemed to be little discernable performance difference over the old progressive. It made a lot more cool carb noise but, not much more in the performance department.
Now, on another car, I am planning on installing a new Weber 38/38 DGAS, center mounted carb with a "supercharger", blow through. I have already worked out the power take off to run the charger but, I haven't got the supercharger I want yet.
In any event, I never had any problem in starting and running the old progressive.
Still, of course, for stock use, FI is where it's at, dual carbs are very fun and I wonder how the supercharger will do.
Phil

[red-beard]

Here's the kit!





The Jets for the 3 barrel carbs!



$29 for those???????

James