Has anyone ported a Solex 40/44 carb for Vacuum Advance

Sorry, here is the picture -

Some good info

 

http://www.thesamba.com/vw/for...t=544940&start=0

OK, I think I answered my own question.  Upon looking further at my carb, once you drill out the brass plug where the port is on my picture (only partial way into body), the carb has a port that turns 90 degrees down from there and runs into the throttle body from which it gets the vacuum.  However, "jjr" (member back in 2010) posted that he had to also drill out a port bigger in order to get sufficient vacuum flow.  I'm not sure if he meant the port going the throttle body which looks to less that 1/16".  Can anyone comment on that?

Thanks Alan.   I saw the beginning of this post on Samba or another that started with the same question, but did not see all that followed.  That complete thread told the story.  

From GTman, Dec 2013 

You need to do something more than just remove the brass plug and install a nipple.  You need to drill out the vacuum opening in the carb body behind the plug.  I found that the vacuum opening was barely the size of a small paper clip and very restrictive.  I drilled out the opening to 3/32in. and was able to increase my vacuum signal to 10inHg.  I also cleared up molding junk in the throttle body vacuum opening to make it less restictive as well.  The exercise is to make the all of the vacuum openings communiating within the carb and thottle body as open/unrestrictive as possible.

 

Sorry, It wasn't member "jjr" it was "GTman" and I now understand what he was saying.  It's all good.  Back to work, I'll let you know if I'm buying  new carb or have improved my cars performance as soon as I get done.

I had mine done at LobBugget (AJ Simms) - he did it for $60.00.

 

I'm kind of amazed at how easy it looks in that Samba post.

 

Ted

It was easy.  I'm all done.  Will reinstall tomorrow after the JBweld dries overnight.  Will post pics and news of the 40HP increase and 30MPG gain I get.

What kind of vacuum did you connect, a Bissell, a Rainbow, or a Dyson?

forgot the emoticon  !!

It was a Hoover Deluxe.

You know, seriously you guys are both amazingly helpful but also fun at the same time.  Thanks for being part of my day today.

Hello Craig:

 

I am happy that my old post was helpful. 

 

I did this a step at a time, first just removing the brass plug and then installing he brass nipple, but found I was only getting a very weak vacuum signal. 

 

I scoured all internet sites and found a good one from the UK that explained the need to really open up the port feeding towards the venturi to the inside diameter of the nipple, and then open up the port 90 degrees down going towards the throttle plate.  I made sure all of the drilling debris was out of the holes using carb cleaner and compressed air.

 

I even went a bit further and slightly opened the port leading into the venturi just above the butterfly.

 

Also, be sure to check that the backing plate in your Pertronix distributor moves freely to allow full vacuum actuated travel.  Mine was limited because it hit against the rubber wire grommet.  This was another reason why I was not getting the full amount of vacuum advance needed.  I ended up trimming a portion of the grommet sitting inside of the distributor to clear the backing plate then all was good.  

WOW!!  OK, that was easy.  It took a little longer than I thought but nothing that was rocket science.  Since I had to take one carb off to drill for vacuum port, I took both carbs off and got re-build kits.  The rebuild was necessary anyway because I was having terrible fuel mileage so I wanted to confirm carbs were OK and Jets were what they should be.  Everything was fine.  Jets are 55 and 130.  Floats, diaphragm and internals are new.  After getting everything cleaned and ready to re-install the nightmare of nightmares actually happened.  With the left carb in place I could not get my vacuum tubing onto the new nipple, so I pulled the carb up off the mounting bolts to get more room and out of the corner of my eye I see the mounting bolt  washer slide off the carb and into (not the engine compartment, no, that would have been too easy) the MF fell into the manifold.  I am 5 minutes away from trying to fire it up and now I'm thinking I have to pull the engine. SH!@#%$^!!  Then again, sometimes I'm so lucky it doesn't seem fair.  I took my magnetic extension and fished for about 10 minutes and came up with a washer on the end.  Hallelujah.  So I pour gas in the carbs, crank it over and what do you know, amazingly it ran. 

Results are promising.  Very strong acceleration, smooth, no flat spots, good torque, etc, etc.

Runs better than it ever did.  Since it is going into hibernation for the winter I will not see if fuel mileage has improved until May.  

 

Thanks to all for the input, GTman in particular for the thread on extra drilling needed.  

 

Good stuff.

With the vacuum advance, Craig, you will probably be able to use one size smaller idle jets. That's where the mileage increase comes from- cruising at part throttle on a leaner mixture, which isn't possible without the increase in advance. Congrats on a job well done, and thanks to GTman for sharing. Al

FYI - I ended up drilling out the vacuum ports of both carbs thinking that I would run the vacuum lines from each into a tee and then to the distributor.  I heard that doing this would help with any vacuum pulse that may come from running only one distributor vacuum port. 
What I found was that one carb (passenger side) produced less vacuum than the other carb, and when teed together ended up decreasing the overall vacuum at the distributor. 

I gave up on the teed idea and ran only the driver's side carb vacuum to the distributor, capped the passenger side carb vacuum port, and that was that.

Did someone say "rocket science?"?

GTman (my apologies; I can't remember your first name!)-

 

Did you try running it teed into both vacuum ports?

Look up above, Yoda......

 

He dood that and it didn't work as well.

 

Apparently, "The Force" is weaker in one carb than the other.

Gordon- He said that when "teed together ended up decreasing the overall vacuum at the distributor". He doesn't say if he tried running it that way or just tested it with a vacuum gauge. 

Hello All:

 

When I ran vacuum lines from both carbs to the tee, I measured the vacuum from the single output line ran to the distributor and noticed that it was about 3-4 inHg.  This was weaker than the 10 inHg signal I was getting from the driver's side carb, though the vacuum signal was cleaner with little or no pulsations

 

I drove the car running the teed lines, and didn't feel that I was getting the same amount of vacuum advance as I was just running the vacuum feed from the driver's side carb (which again produced about 10 inHg max vacuum but had a pretty pulsed vacuum signal).

 

I then checked the vacuum at the passenger side carb alone and noticed it was providing about 3-5 inHg (max vacuum).  The only thing that I did differently when I vacuum ported the passenger side versus the drivers side is that I did not open up the vacuum advance port running through the throttle plate above the butterfly.  I figured that the weaker vacuum carb was diluting the strong vacuum signal from the driver's side carb when teed together.

 

So rather than taking the passenger carb off and going back through it, I just capped the vacuum port and ran the distributor off the driver's side carb with the strong vacuum signal. 

 

And as background, all of my vacuum measurements were run under operating conditions, driving the car around having a vacuum gage on the passanger seat with vacuum tubing running outside of the car from the engine compartment.  So I was checking it under load and cruising conditions.

 

I also played around with the Pertronix distributor vacuum advance unit using a suction source and a vacuum gauage and found that it needed at least 5-6 inHg just to start to move it, and 10inHg to get it to fully advance.

 

I hope that this information is helpful.

 

Thanks, Grant

Thanks for the info Grant.

More and more of us are getting "Data Crazy".

 

I think it all started with "Air-cooled Bruce" (or, for lack of a better scapegoat, let's just blame him, anyway) and the airflow and temperature data he's collected, from all over the engine.  Who knew that the sump temp acted that way?

 

Now....Don't get me wrong.  I think this is FANTASTIC!  Look how much better we can improve the operation of our engines, based on real data!!

 

Getting real data from Bruce, Grant and others is like "Manna from Heaven" (or, at least, a really good, North Umbrian, Italian dinner, served by Giada, eh?)

 

I always thought that the power pulses seen by the carburetor were too far apart to drive a decent vacuum signal from one carb alone, as they would be lumpy, or "'pulsed'.  Grant has proven that otherwise.  His Disti is driving his engine just fine.

 

I wonder what other questionable choices I've made?  

 

 

 

 

 

"I don't know what that distributor wants."

 

Just like most of our wives......

looking at the first picture, their is a vacuum port already on the bottom of the carb, its direct manifold vacuum, you can use it, just set your advance with it disconnected. when you plug it in watch your advance go up, dont run more than 46 total. bill

 

Thanks for the reply Bill.  That picture showing the text and arrow pointing to a nipple is not my carb, it was from the internet.  If you mean the capped port near the idle idle mix screw you are probably right but that does not seem stock, someone probably added it, if you mean the barbed port in the rear down low, that would be off the manifold and in both cases yes that would give manifold vacuum, but not sure I want Manifold vacuum.  Don't know for sure, the debate between manifold and ported vacuum is just beginning in a new thread.  

 

craig

Did someone say nipple?

Quick, somebody call Vince.

Just wow.

go direct manifold vac if possible.all computer cars push as much timing as possible until it knocks, on a carburated car this is the best way to achive as much timing as possible without burning a piston. bill
 Bill and Jean Demeter


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