Which New Carbs; Best Mileage?

Carbs & F.I.

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hypercircle
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Which New Carbs; Best Mileage?

Post by hypercircle » Tue Sep 25, 2007 9:54 pm

Hi all,

I'm running the original dual 34 PDSIT solexes on my 1776cc pancake engine. The carbs are old (duh) and getting way worn out. My mileage has dropped below 16mpg. It hurts. I'm trying to reach the golden 20mpg+ area - and more power wouldn't hurt. I'm going to buy new carbs, but honestly, every mechanic i've talked has told me different stories, and now i don't know what to believe. I know to stay clear of center mounted progressives.

So far i've looked at:

Dual 34mm Solex Carbs with electric chokes - $300
Dual Weber ICT carbs - $400
Dual 40 Weber IDF carbs - $700

I was under the impression that the IDFs would be the best mileage since you can tune them better, but i've been told that the 34mm Solex Carbs are the best way to go if i want fuel efficiency.

What say you, oh great VW gurus?

:drunken:

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Amskeptic
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Re: Getting New Carbs; Best Mileage?

Post by Amskeptic » Wed Sep 26, 2007 6:48 am

hypercircle wrote: original dual 34 PDSIT solexes on my 1776cc pancake engine.
The carbs are old (duh) and getting way worn out.
My mileage has dropped below 16mpg.
I'm trying to reach the golden 20mpg+ area - and more power
The engineering of the original carbs is good, you get the best linkage in the business, air preheater, and the central idling circuit gives you great flexibility as far as adjustment and compensating for wear, such as throttle bushings. You'll also get the best chance for decent fuel mileage.

Carbs don't really "wear out", other than throttle bushings which can be compensated for with the centrl idling circuit. They do, however, get dirty. You can clean them, synchronize them, make sure your distributor advances are working smoothly, and then decide if new carbs are necessary. Most 1700 Type 4 engines with the factory dual carbs get anywhere from 18-22 mpg when they are correctly adjusted.
How's the compression?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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RSorak 71Westy
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Post by RSorak 71Westy » Wed Sep 26, 2007 9:40 am

I have a set of the CB Perf Dual Solex's and like them, but they do need a couple mods before bein put to use....for better reliability and performance..
I get i little over 20 MPG on my 1600 w/ them and flawless performance.
Take care,
Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.

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satchmo
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Re: Getting New Carbs; Best Mileage?

Post by satchmo » Wed Sep 26, 2007 1:01 pm

hypercircle wrote: What say you, oh great VW gurus?

:drunken:
I'm no guru, but I've run both the stock solex carbs and a set of dual Dellortos. The stock carbs beat the aftermarket stuff hands down as far as drivability is concerned. The linkage is way better too. You will struggle with tuning/synchronizing with either system. With aftermarket carbs, you not only have the cost of the carbs, but you have to buy a linkage, get manifolds, tap the manifolds for brake booster vacuum, figure out a way to get ported vacuum for the distributor advance, how you gonna deal with crankcase vapor recirculation, and what about the fuel tank vapor/recirc????

Better to clean/rebuild the stock carbs, get the throttle shafts rebushed if they are sloppy, and get them properly tuned. That's what I say.

If you go with something else, box up all that stock stuff and send it to me :bom:

Good luck, Tim
By three methods we may learn wisdom:
First, by reflection, which is noblest;
second, by immitation, which is easiest;
and third, by experience, which is bitterest. -Confucius

hypercircle
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More options!

Post by hypercircle » Thu Sep 27, 2007 10:24 pm

Here's what I got so far. Getting there. I'm very new in the Volkswagen world. :P I had the engine recently rebuilt very well, so all inner workings are great.

So there's a popular vote for rebuilding the stock carburetors. To be honest, they are not in bad bad shape. All the linkages are in good shape and they don't wiggle at all. The thing about them is that they ARE old... so they don't keep their settings (lately, the van keeps shutting off when i idle)
What rebuild kit should i buy if i feel the need to restore my carbs over the winter? Expect perhaps 20mpg?

Also, keeping in mind a pair of CB performance dual Solex - 20mpg

Or, Contact some Italian Dude for Dellorto's and do a bunch of stuff(though not complicated, still complicated:P). Sounds tempting but 200 in linkages and 300-400 in carbs to $550 avg. But, 25 mpg.

So, before i make this decision, i need to freaking understand carbs better. Words like, 'stock dizzy' and 'vacuum port' are not making as much sense as they should... Ventuuri size also varies from carb to carb, but i think i want something like a 30mm or 32mm on a 1776cc engine?

I guess what i'm trying to wrap my mind around is why would, say, Dual Dellorto get better mileage than the stock solexes? Is it because the 36 are a little better sized for the engine? Or is it because it has been 30 years and there's simply smarter carburetors nowdays.

I've been told that with the webber ICT's i will also get around 25 mpg.

Alas, I've been inspired to go learn a little bit more about carbs :P If anybody wants to throw some pointers, it will be gladly appreciated. Thanks for the posts oh great VW gurus.

:drunken: Cheers! :cheers:

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spiffy
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Post by spiffy » Fri Sep 28, 2007 8:59 am

I have seen folks use the old pinto carbs as well, although only on single carb set ups. (don't shoot!) :geek:
78 Riviera "Spiffy"
67 Riviera "Bill"

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dingo
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Post by dingo » Fri Sep 28, 2007 12:21 pm

What you are trying to find is the widest possible zone of the ability to do work, at engine speeds that it will most commonly see. The dual carbs will allow a wider "zone" vs a single carb - which would have a relatively narrower useful "zone
".

which is why stock 'duals' operate as a 'single' at idle and 'dual' at higher rpms...best of both worlds...not so ?
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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spiffy
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Post by spiffy » Fri Sep 28, 2007 1:15 pm

The Air-Cooled Ranch wrote:Ay, yi yi - Mike says:
I have seen folks use the old pinto carbs as well, although only on single carb set ups. (don't shoot!)
MIKE!!! Dude! Really now... Can you stand still for a second while I get my scope zero'd in on you :joker:
I was hoping someone would roast my comment :geek: However, the guy that has it on his bus is very happy with it (I wouldn't do it) but that is his cup of tea and it enables him to go all over hell in his bus. Of course he is not the type to do much wrenchin on his bus either.....
78 Riviera "Spiffy"
67 Riviera "Bill"

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dingo
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Post by dingo » Fri Sep 28, 2007 1:51 pm

From my old Haynes Pub.1974 :

"Although the model Solex PDSIT 34 2/3 is described as twin carburettor* the term is misleading. There is in fact, ONE carburettor in TWO parts....
.This means only one adjustment for slow running and thus gets rid of one of the major problems of twin carburettor adjustment.
In all other respects it is a normal Solex PDSIT 34 but it certainly puzzled us at first "

* Brit version. I love their candidness about being 'puzzled at first'
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

hypercircle
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Mmmmm Dell'Orto...

Post by hypercircle » Fri Sep 28, 2007 9:39 pm

First, thank you for the educational mode :cheers: I am learning well.

Jim, you're making a better and better case for getting dual Dell'Orto carburatori*. I looked around and heard nothing but good things about these guys. And i AM part Italian. It feeels right!

But a couple of things i'm worried about. If i get them used, won't i have to go through the whole rebuilding process with them? after all, they too can go bad. How much are their parts and how common are they to foul up on me?

Another thing, 36 DLRA's are two barrel carburadores * ; Is that basically why they are better on the van? Two barrels is more efficient than say, ICT models right? ; it allows for air/fuel mixture to go into each cylinder independently.

Also, my engine is from a 1974 type 4. I was under the impression that in 1974 they made 1.8 liter engines, which i thought were at 1776cc. I could, to my chagrin, have misled you to think that it's 1.7. I will get a rubbing of the engine and look in the book. Still, the 36 DLRA's should be good on 1.8 liter engines? (if not with more reason?)

I will invest if i need to in order to do it right. I hate doing something twice; and i'm planning on making my Van my truck/motor home, thus keeping it for a long time :cheers:

I've found so far :

http://orangecounty.craigslist.org/pts/427942861.html


What kind of stuff should i be looking if i, say, decide to indulge my Volkswagen in the Italian carburetor trade? As in, what questions should i ask the carb sellers? (what size engine? how old they are?) What kind of manifold/ air cleaner / type 4 linkages?

If i do buy linkages, what kind would be the best for the Van?

And do not worry, my mechanic won't allow me to put a progressive Webber on my T4. Seriously, i actually had one, and i pretty much gave it away. He recommended the 34 Solexes by CB performance. He's been doing this since the beginning of time, so i trust him. But he likes to keep things simple. Which is why i'm asking you guys :)

Cheers, and thanks for the help everybody!! :cheers:




:drunken: *haha, italian and spanish! :drunken:

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Ryno
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Post by Ryno » Sat Sep 29, 2007 5:46 pm

I couldn't be happier with my drla 36 dellortos on my 1.8L. They get decent mileage and they're consistent. I am running the CB linkage and I'm happy with that also. There's a guy over on TS that goes by the username of Paul Wilson, I bought all of my rebuild parts for the carbs through him and rebuilt them myself, dellortos are simple and the best choice other than FI in my opinion.
Ryan

1985 Westfalia

hypercircle
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Venturi Size

Post by hypercircle » Sun Sep 30, 2007 5:50 pm

Hi Ryan,
what size venturis do you have on your 1.8L Van?

I contacted alfa1750, he's selling the Dell'Ortos for 375. He recommended for best mileage that i should put 28mm or 29mm venturis. I'm worried that doing so will take the spunk out of the van tho... Maybe go for 29mm? I was originally going to put 30mm in there.

How do you do on mileage and power?

Getting close to making the final purchase...:drunken:

-Miguel

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Post by Ryno » Mon Oct 01, 2007 6:18 am

Miguel,

I am running the 30mm's with an SVDA dizzy from aircooled.net, in my opinion this is a wonderful combo. I really can't remember what I have for jetting though.

I have more than enough power and my mileage hovers around 20mpg at around 65mph on the highway.
Ryan

1985 Westfalia

hypercircle
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Getting ready for the purchase...

Post by hypercircle » Tue Oct 02, 2007 8:40 pm

Oh man, :pale: i can't believe you were so close!!!! For all that it counts, having so much power that you broke your axle is kinda cool :drunken: ... What kind of monster where you guys racing?

Ok, so i'm nearing the final moment!! I'm going to get the 36 Dell'Ortos tomorrow (Wednesday) from ALFA1750... I'm psyched. - I will ask him to get it ready for the velocity stacks and have it tuned for a 1.8 type 4 engine and 30mm venturis. Both of you guys like the 30's, and i have a feeling i'm going to love them too :) I like mileage, but my van is also my truck... and there's hills everywhere (Seattle!). Perhaps in the future once i get more adept with carburetor tuning, i will put in 28mm venturis before very long trips...

I'm also going to get the VW manifold, linkage and air filters from CB. Along with that i'll get the velocity stacks and that handy Dell'Orto book.

I'll start looking for the Universal Corp. Tiger CDI boxes. If i don't find these rarities, what would you recommend?
-on this note, i've been told that electronic ignition is a very good idea.. can i run EI with CDI boxes?

BTW; thank you for the CDI explication. It makes perfect sense. My friends and i made a propane-oxygen potato gun. We got the best results with higher voltage igniters (they allowed for more screws inside the chamber, thus creating a very impressive spark and an even more impressive ca-BOOOM!!! :bom: )

I will do a little more research and get a list compiled of everything i'm going to buy ( with links )

I've been dreaming of these carbs (not joking, i have..) and my Volksy is very ready for them!! This is going to be SWEEEEET!:cheers:

Cheers!!

Miguel :drunken:

hypercircle
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Gizmos...

Post by hypercircle » Tue Oct 02, 2007 9:28 pm

1) Dell'Orto 36 DRLA from Alfa1750 @30mm venturi + extra rebuild kit. $400 ish.
Ebay # 260165564024 :cheers:

2) Manifold / Linkage/ Air filter - $172.95+ship
http://www.cbperformance.com/catalog.asp?ProductID=538

3)Velocity Stacks - Question, what height? 1' 5/8" - standard? - $ 28 for 4 (right?) lol
http://www.cbperformance.com/catalog.asp?ProductID=512

4) Dell'Orto Tech Handbook $10
http://www.cbperformance.com/catalog.asp?ProductID=2

5) Universal Corporation CDI unit. (pending contact w/ them & price)
http://www.universal-co.com/index.aspx

Everything sound good??

Should i check if my Dizzy is the right one? How do i know if i have the right one?

Cheers!! :drunken:

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