dual solex "interchangeability"?

[SixVolt]

Perhaps this should be titled "linkage interchangeability", but here goes...

'74 Westy 1800 w/ 2.0 pistons aftermarket weber 40's.

I'm going back to "close to" stock. I picked up these rebuilt solex's from a '72

I previously came accross a complete set up of dual solex's from a '73 with all the linkage and cross pipes included. (I actually think one of these carbs may have been a '72 originally). Here is the 'unrestored' left carb that came off the '73.

1. Can I use the linkage set up from the unrestored '73 carbs with the rebuilt '72 carbs?

2. The rebuilt carbs came with the 72 oil bath cleaner. I know the "pizza slices" sit on top of the carbs, but what about the oil bath container? Is there something that bolts on top of the engine case that it sits on?

3. Should I take the float assembley in the rebuilt carbs apart to measure? (I bought them rebuilt). Or should I just try to bolt them up and see what they deliver?

4. I see two throttle plates on each rebuilt carb. One on top and one on the bottom. Should I assume the top plate is controlled by the choke element and the bottom plate by the accelerator? (I may be confused on this becasue I don't have any linkage hooked up to the top plate).

5. I think the rebuilt left carb is from an automatic tranny bus. (It has that certain screw). Does this make a difference installing it on a manual bus?

So why am I getting rid of the weber 40's? I prefer stock or "close to" stock stuff. In addition, I'm certain someone other than me can probably get them to run right. I'm really not happy with them.

[Karl]

68-79 Bentley, section 3, page 30 shows the carb numbers and jet sizes.

The 72 only round oil bath air cleaner will only work with 72 only short manifolds.

The 73/74 square plastic air cleaner will only work with the taller 73/74 manifolds.

Here is a pic of the 72 manifolds:

Here is a pic of 73/74 manifolds [sorry, best I could find]:

To mount the air cleaner, you need the 2 half moons that mount to the case. #1 here:
http://www.ratwell.com/technical/Microfiche/t201600.gif

[SixVolt]

Thanks Karl,

I'll check the Bentley.

Along with the carbs, the guy threw in a nice set of powdercoated '72 manifolds.

This raises another Q.

On the '73 manifolds there is an outlet for what I will call a 'crossover style' pipe that runs out of the front side, (front is front), of each manifold and clips to the engine compartment. It doesn't look like the '72's have this pipe.

1. What does this pipe do?

2. Is there a performance enhancement with the '73 manifolds?

3. What about the '73 linkage? Can I use it with the shorter '72 manifolds?

4. Is the upper 'throttle plate' on both carbs run only by the choke?

5. Can either the '72 or '73 iddle fuel delivery line be used with either manifold? Or do you have to use the '72 fuel deleivery with the shorter manifolds and the '73 only with the higher maniflolds?

6. Lastly, This vehicle is running with an electric fuel pump. Do I need to be concerned about fuel pressure with solex's? If the weber's are handling it, does that indicate I'm ok?

7. The half moon clip on ratwell's site looks like it's depicting a paper air cleaner system for the '73-'74. Is the one for the '72 oil bath the same?

Appreciate it.

[barefootwestie]

Thanks Sean for asking the Q's and posting the pics. I will definitely bookmark this thread.
_________________
My Bus Restoration Blog
https://myvolkswagenbus.com/

1973 Westfalia
"Getting better....one repair at a time."

Other VW's owned through the years, in no particular order:
'67 Beetle,
'67 Ghia Hardtop,
'72 Ghia Convertible,
'72 Westfalia

[Karl]

The pipe that bolts to the front is for EGR.
Remember the pic I posted of the taller 73/74 manifolds?
Look at it again:

On the left one, you can see the 2 6mm studs for the pipe. On each manifold you will see the round vacuum diaphragm. That is the EGR valve on each one.

You need to keep the linkage together with each style/year of carbs.
The decel valve on the left carb is operated by the cross bar.
In the pic above the person has [for some unknown reason] 3 decel valves.......

The Bentley shows 2 different pics of carbs. 68-79 Bentley section 3 pages 12 and 13.
On page 12 figure 5 - 5 is the left carb of a 72. Look at the linkage bar and the left end of it.
On page 13 fig 5 - 8 is the right carb of a 73/74. Look at the linkage bar and the right end of it. The left end will resemble it. Not that goofy end on a 72...... Compare the left carb pic of the linkage bar with the left one above. The decel valve on the bracket is the left cross bar bracket.
The cross bar pivots on the ball.

[SixVolt]

Thank you Karl.

From studying your response, Bentley, the photos you provided and the carb/manifold items that I have, I can see the linkage setups are different.

While the linkage is different between '72 and '73/'74 models, is anyone out there aware of whether you can still attach the 73/74 linkage to the '72 carbs? I'm assuming the ansewr is no, but thought perhaps someone out there has tried it.

As indicated earlier, my problem is I have two nice rebuilt '72 carbs, short manifolds and a nice powdercoated oil bath, but only partial '72 linkage parts. I have the full linkage for the '73/'74 set up, but with filthy '73 carbs. Isn't that life! (Who said FI was more complicated!)

I'm not certain the pipe I described in my earlier post was the EGR. I see the '72 manifolds don't have those dual 6mm studs with the pipe running between the manifolds. I'm sorry if that was what I was describing. I was referring to this pipe (shown below) that runs off the side of the manifolds, but runs in front (front is front) of the engine. It looks like both the '72 and '73/'74 manifolds have a port for this pipe. Here is a photo:

What exactly is that pipe called? Can I just block off that little port that appears to the right side of the middle of the pipe? Or does that hook up to a vacuum line?

Here is what I have of the partial linkage items from the '72:

It doesn't look like I have all of it, which is why I want to "borrow" what I can from the '73 linkage. Here is the '73 linkage:

Lastly, I have these two, (I'll call them "half moon") mounts for the air cleaner fromt the '73 set up shown in the photo below. Does it look like they are the same as the '72? Will they work with the oil bath?

Any help on the earlier questions from anyone is appreciated.

[60sbeetleguy]

If anyone needs some manifolds, I have a set from both a 72 and 73/74.
PM me if interested.

Al
73 Westy

[VWLover77]

Good lord, no wonder they went to fuel injection!!!

Back to the regularly scheduled thread discussion.....

Don
_________________
Don

1978 Westy
1971 Super Beetle Convertible


"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world." - J.R.R. Tolkien

[Karl]

The pipe you have in the 1st pic is the balance tube. It connects to the lowest point on each manifold and also feeds the brake booster.

The half moons you have are for the square plastic 73/74 air cleaner.
The oil bath ones are curved and do not stand as high. I believe I have a pair around here somewhere.......

In the second pic, the tube assembly is called the 'mixture distributor'.

The 'bent' cross bar you have is 72. 73/74 is straight. Your problem is the mounting brackets where the pivot balls are.....

[Amskeptic]

The later carbs have mounting bosses cast into the upper covers for the later style crossbar linkages. The EGR pipe that bolts to the "high-rise" manifolds is what I like to call the balance pipe, it gets signals equally from all cylinders. The brake booster pipe that attaches with the rubber elbows to intake tracts #3 and #1, I like to call the "brake booster pipe" because it does not serve any balancing sort of function. Sean, you would prefer the later manifolds with the balance pipe and the booster pipes both. You should be able to rustle up a complete set of parts, including the preheater duct, and you will eventually prevail with a nice running bus that I get to drive...
Colin
_________________
www.itinerant-air-cooled.com

[twinfalls]

Colin ?
On my 74 1800cc, when I removed the EGR, I junked the balance pipe.
Was that a bad idea ? Should I put back the balance pipe ?
_________________
Stock 1974 US Westy, AW-A 1800cc dual carbs. Twin Falls is my favorite site on the Churchill river in Manitoba.

[SixVolt]

Thanks to all for the informative data.

Ok, I guess the '73/'74 will have to be rebuilt. I'll try to get a quality rebuild kit. I think ratwell mentions something on his site. The '72 stuff can, hopefully, be traded for some FI stuff!

It sounds like I need a "preheater duct" and the air filter/cleaner assembley. I'll start looking.

Since I wont be reinstalling the EGR, I am assuming some, perhaps one?, of the metal lines running off the set up wont be used?

As I see it, there are actually three pipes on the '73/'74 set up. My confusion is they are referred to by different names.

1. The pipe with the "rubber boots" that runs between the manifolds with a nipple for a brake vacuum booster line. (Colin=brake booster pipe) (Karl=ballance tube)

2. The solid metal line that bolts to each manifold with two 6mm studs. (Colin=ballance pipe)

3. The "spider like" pipe that feeds or distributes the fuel/air between the two? (Karl=mixture distributor)

On the "spider", there is a small nipple opening that a rubber line connects to. What is it and where does this line go? (See photo below)

Also, one of the "branches" off this "spider tube" goes nowhere. (It is the one "heading southeast" going off the bottom of the photo. It is right next to the little rubber line.) Is this the former EGR pipe connection? (See photo below)

[twinfalls]

[Karl]

The EGR pipe has ZIP ZERO NADA effect on balancing the mixture or idle speed. It is NOT a balance pipe.

It bolts to the 73/74 intakes up top at the BACK of both of the EGR valves. The end that is pointing to the front of the bus goes directly to the EGR filter.

If you have ANY vacuum in that pipe at idle, you have two things dramaticly wrong: you either have manifold vacuum connected to the EGR diaphragms and are holding them open OR you have stuck open EGR valves.

LEARN how your emission systems work!!!!

Go to your 68-79 Bentley section 3 page 27 figure 7 - 2. It shows EXACTLY how it is laid out.

From the muffler the exhaust goes: thru EGR filter, thru tube bolted to manifolds, thru the EGR valves into the intake tract. Ported vacuum, vacuum from above throttle plate, appears after you open the throttle and opens the EGR valves.

A good rule of thumb: any tube that has rubber connections is for vacuum, any tube that is bolted on is NOT.

[twinfalls]

[Amskeptic]

I do love a spirited conversation, how could we all not learn ever more.

Karl, I do have vacuum in the Metal Pipe That Bolts To The Manifolds. I gutted my EGR pintles and sealed up the valves and the egr take-off at the front where it used to go through the front tin..
Remember how the Type 3 Solexes would suffer from semi-dead cylinders at idle because of the dramatic pulses as the engine does the 4-3/2-1 intake order? A balance pipe does not have any directional breathing going through it, it just has a pressure wave that zings back and forth between the cylinder banks. This most certainly does even out the air flow through the carbs and it improves the idle. The brake booster line cannot contribute much to this pressure wave cancellation because 3 and 1 are separated by a full 360º.
I can feel it from here, your disbelief, but read up on pressure pulses and look at any dual exhaust set up where quietness is the goal, there is a balance pipe between the two to steady the airflow (on my '62 Lincoln, the balance pipe is the exact same diameter as the exhaust pipes themselves), the physics are exactly the same for the intake side. With our low velocity dual carbs, we want steadier intake air. Without the EGR/balance/whatever pipe, you will get more barking in the carbs and more fuel spray liftoff in the throats. While most modern intake tracts use pressure pulse to help induction (tuned manifolds yadayada), we of 67 hp want tractability. Let's visit and I will put my engine up against any sample you have to offer. My engine can't tear its way out of wet paper bag, but the driveability and docile idle is first-class.
Colin
_________________
www.itinerant-air-cooled.com

[SixVolt]

Hopefully this 'spirited' thread will soon end! I greatly appreciate both Karl and Colin's input as they have advanced my personal knowledge to the point where I am now glad the other 'bay' I drive has fuel injection!!!! In the spirit of Don's earlier post: "Who said carbs were easy?"

Anyway, I examined the linkage 'set ups' and carbs closely and I am still wondering why I can't bolt the '72 carbs to the '73 linkage set up? I'm sure I'm wrong, but check out these two photos showing the linkage 'set ups' and the carbs. The first is the rebuilt '72 carbs. The second is the '73/'74 right carb with the '73/'74 linkage set up. Maybe the first set are not really '72 carbs???

Anyway, I really appreciate everyone's commentary.

Here are the '72 carbs:

Here is the right '73/'74 carb/linkage. (The left carb is similar):

[Karl]

[twinfalls]

1 EGR valve / 2 EGR valves.
I had, and I have no intention to upset anybody.
I had a hard time to understand "my" EGR, and how to remove it properly.
That is because, there has been many different EGR setup, AND, books are confusing.
After a lot of hard work, I think I do know about this issue, and perfectly know, it, about my bus.
Bentley Fig 7-3 shows a 2 EGR valve setup, with a comment that says: 1974 models have 1 EGR valve, iso, 2.
BS; Bentley was no use, helping me.
Haynes did a bit better, on this issue; Fig 2.10 page 51 shows 1 EGR valve setup. ( after some guessing, the A is the valve ).
Well, I helped myself.
Because books do not help about 1 EGR valve configurations, I was just willing to give worthwhile infos.

On this forum, I just want to help, and keep my bus running.
I rather care not about who is right or wrong.
Well, as we like to say at my place : "if you do not want it, I put it back in my pants."
_________________
Stock 1974 US Westy, AW-A 1800cc dual carbs. Twin Falls is my favorite site on the Churchill river in Manitoba.

[satchmo]

Still, I would wager that the linkage for a '72 dual carb set-up would NOT work with the components from the 73/74 style. The linkage bar on the 73/74 is shaped to clear the box/paper type air filter, not the round/oil bath air filter.

However, (and I think this is the question you want answered) I think you CAN use the 72 carbs on an otherwise stock 73/74 system (manifolds, air cleaner, linkage, etc). Both the 72 and 73 were 1700cc engines, so jetting is not an issue. I used carbs from a 1700cc engine on an 1800cc engine without difficulties too. Just use the linkage mounting brackets from the 73/74 set-up on your 72 carbs. Then you are in the pink.

The short manifolds from the 72 system will only work when used with the other components from the 72 linkage and air cleaner. THe taller manifolds from the 73/74 must be paired with the box/paper air cleaner and linkage. The carbs themselves don't change that much and can be interchanged.

Others will correct me if I am wrong.

As for the EGR tube, I took that off when I rebuilt my 73 engine and plugged the holes in the manifolds with JB Weld or something. Colin recommended I put it back on to use as a balance tube. His reasoning made sense, (this is also recommended in the Dellorto carb tuning book for 'single throat' intake manifolds) so I put the tube back on. And, honest to goodness, cross my heart, hope to die, stick a needle in my eye, it made NO difference. At least not that I could tell.

Good Luck, TIm