Great Weber tuning info

[Ron Delmendo]

Hi folks-

Seems this topic comes up fairly frequently. This is a great site for information on tuning the Weber IDF 40. Even a newbie such as myself can follow the instructions...

http://www.carburetorclinic.com/tuning_ ... uretor.htm

[Glenn Ring]

I know Mark Harney and he's a really nice guy. He also know Weber carbs really well.

[Bob Lee]

Hi folks-

Seems this topic comes up fairly frequently. This is a great site for information on tuning the Weber IDF 40. Even a newbie such as myself can follow the instructions...

http://www.carburetorclinic.com/tuning_ ... uretor.htm

Ron,
The best tip I know is to take your Webers' and get them as far away from your 356 as possible, the factory knew what they were doing with Zenith's and Solex's But then again what do I know

Back Under my rock I go
Bob Lee
356 Registry member 16135
Porsche 356 Club member
912 Registry member

[Frederic Prince]

Hi folks-

Seems this topic comes up fairly frequently. This is a great site for information on tuning the Weber IDF 40. Even a newbie such as myself can follow the instructions...

http://www.carburetorclinic.com/tuning_ ... uretor.htm

Ron,
The best tip I know is to take your Webers' and get them as far away from your 356 as possible, the factory knew what they were doing with Zenith's and Solex's But then again what do I know

Back Under my rock I go
Bob Lee
356 Registry member 16135
Porsche 356 Club member
912 Registry member

well said !!!

fred ©

[Dave Wildrick]

Hi folks-

Seems this topic comes up fairly frequently. This is a great site for information on tuning the Weber IDF 40. Even a newbie such as myself can follow the instructions...

http://www.carburetorclinic.com/tuning_ ... uretor.htm

Ron,
The best tip I know is to take your Webers' and get them as far away from your 356 as possible, the factory knew what they were doing with Zenith's and Solex's But then again what do I know

Back Under my rock I go
Bob Lee
356 Registry member 16135
Porsche 356 Club member
912 Registry member

Bob,
I know you are a purist, but what if the 356 you bought already had Webers on it, and you don’t have $1650 for Zeniths or $2450 for Solexes from NLA (including core charges)?
Are you saying to dump them and get a loan?
And that the Maestro was a jerk for recommending Webers?

[Sebastian Gaeta]

Bob,
I know you are a purist, but what if the 356 you bought already had Webers on it, and you don’t have $1650 for Zeniths or $2450 for Solexes from NLA (including core charges)?
Are you saying to dump them and get a loan?
And that the Maestro was a jerk for recommending Webers?

Dave,

I have a story somewhat like the scenario you described.

When I bough my C coupe in '92, it had Webers. I was quite nervous to show it to Vic Skirmants as I knew he was a Solex/Zenith guy, but it ran great with no flat spots as is common with those carbs, and I had others things that I wanted to do with the car.

The first thing Vic did upon seeing the carbs was to make the sign of the cross and step back as if he were looking into the eyes of the devil!!

I promised him then and there that I would replace them with proper Zeniths as soon as they started to give me trouble.

In 2007 I found a nice pair of correct Zeniths and had Vic refurbish them so I could replace the Webers.

The Webers were still running fine when I replaced them (15 years later!); I just felt that I should eventually get the car back to being "correct". 8)

Regards,

[Frank Meek]

Hi there
While I understand the "ideals of originality," one must put some of these component choices in some historical perspective. The fact that Eduardo Weber heavily supported the Italian racing teams might be one of the reasons that different carburetor choices were made at Porsche. Indeed, for a short time, Porsche offered optional Webers (DCM's), on the 547/1 Carrera, as Carrera historian Cole Scrogham noted, "to strengthen performance."
Also, clearly, the IDF, (and, really all models including the aforementioned DCM's), are aftermarket applications requiring, at times, more than the onboard tool kit wrenches to optimize their potentials.
As is clear, this is still a matter of some notable historical and mechanical controversy.
Best regards,

[David Baugh]

Yeah, "the factory knew what they were doing". Like the small oil pump with the non-replaceable body (VW had a better idea), the ill-fated thermostatic oil control valve, the archaic 6-volt electrical system, and a few other unmentionables.

My Webers don't cause me anywhere near the headaches & expense that the Zeniths did.

Dave

[Brian R Adams]

Now to the Weber guide in question:

Overall a pretty good guide. If you must run Webers.

He says to determine by eyeball alone that the carbs both come off idle at the exact same time (or words to that effect.) Impossible. I'm surprised he never covered syncing them off idle. As long as they are synced off idle, and are both firmly on the idle stops with your foot off the pedal, that's the best you can do. Whether they actually come off the idle stops at the exact same moment is quite irrelevant if you really think about it (as if you could ever ascertain whether they do so by peering them. How could you even focus on them both anyway?)

Also, he gets caught up in the throttle rod angles, which are not actually critical (something I explain as best I can in my Weber linkage article in the Tech section.) But he says that, looking from behind the car, the rods should both be "vertical", which if memory serves would require splaying the the crossbar arms outboard severely, and for what? All that matters is the the rods lean at close to the same angle relative to vertical (i.e. the arms both come off the crossbar somewhat outboard at the same angle) for symmetry.

[Glenn Ring]

But he says that, looking from behind the car, the rods should both be "vertical", which if memory serves would require splaying the the crossbar arms outboard severely, and for what? All that matters is the the rods lean at close to the same angle relative to vertical (i.e. the arms both come off the crossbar somewhat outboard at the same angle) for symmetry.

He's talking about VW engines.

[John Clarke]

Yes, The Debate will Continue, Webers V what was Left!
If the Weber IDF had been available at the time of the 356 it would probably have been the Carburettor of Choice for the Porsche Factory, As of Course Would be the Dellorto DRLAs that followed. You can only Go With What There Is.
Ask Bob Tomlinson!

Jay

[C J Murray]

Some of the above comments are a bit irrational. Yes, Solex and Zenith carbs look correct and work well. That is rational. But, Webers don't work on Porsches? They worked well on factory race cars starting in the '50s and for many years after. They worked on 911s starting in 1967. In fact Weber had to rescue the 911 from Solex. If Porsche had retained Solex carbs on the 911 VW would have taken over Porsche in the '60s.

The tuning guide that Ron posted is the single best reference for tuning ANY brand of carb. This guide was e-published on a number of VW sites and I found it some years ago. It really boils the subject down to what really matters. If you follow the instructions EXACTLY with NO VARIATION you will get a very good result.

The trick is to hold the throttle STEADY at various rpm points to evaluate the various circuits. Once you have smooth running at the various circuit test rpm points you are most of the way there. Accelerator pumps are the last thing to adjust and only come into play when the pedal is being pressed.

Webers will work well on any engine but they can't tune themselves and most of the people installing carbs don't have a clue how to tune ANY brand of carb.
Cliff

PS-If you really like this tech stuff buy a copy of Passini's Weber Book.

[Joris Koning]

CJ,

I agree with most of the above. I think what Bob is trying to say is that if you have a good pair of Solex or Zeniths there is no real reason to switch especially on a stock or mild engine.

I think Webers became popular when we did not have the quality rebuilding services we have today. This is why Harry especially touted Webers and 050's. When originals carbs were worn out and good used ones could not be found Webers and 050's were a valid alternative. I also believe that Harry had an economic interest in pushing these parts.

The problem is that people read his books and conclude that these parts are superior to the originals parts, they are not. Also with the presence of good rebuilders out there, there is little cost difference between rebuilding your original parts or buying new not exact replacements. I know what I prefer.

Sure if you start talking about hot engines the equation changes a bit. However these engines are outside the original design parameters and subsequent component choices Porsche originally made.

Best,

Joris

[Brian R Adams]

CJ:

I do like most info in this guide, but I'll say again, it has one fatal flaw.

Here's how he syncs the carbs off idle:

"Now, to synch your carbs, loosen the nuts on one downrod, and use the rod's opposed threads to set the carbs so they are opening at the same time."

That's it! Nothing about using the Synchrometer off idle. He just eyeballs the carbs to verify they both come off the idle stops at the same time. Impossible to verify, and even if you could, it does not mean they are synched off idle, in fact I will bet decent money they will be significantly out of synch using this method. Only the Synchrometer can tell you this, but he only uses it to adjust idle sync. That frankly astounds me.

Glenn:

Yes, for VWs, but I doubt the rods need to be vertical on VWs either, as long as they have close to the same angle as viewed from behind.

[Frank Meek]

Hi there
<The problem is that people read his books and conclude that these parts are superior to the originals parts, they are not.>

The next time you decide to change or alter jetting on either the Solex or Zenith carbs on the race track or your driveway, let me know how the Weber design is not superior. And, while I do not change these often for street use, I still like the notion that if I wish to do so, these changes take minutes, with little mess. And, how about those bearing-supported shafts? How much smoother and more maintainence-free are these?
In my humble opinion, these, (and other design characteristics), make a fair case for "superiority."
Best regards,