A satisfied Weber owner, why change?

[rbogh901]

My '72 lives at 4500'. I've owned it since '93. It came to me with Weber 40's that I had rebuilt and the float levels adjusted, then amateur tuned myself a bit, (with some generous help from Eric Shea about 10 years ago), mostly just the idle circuit, and haven't really touched since.

It starts easily hot or cold, (rarely on days below 32F or over 100F), idles well, packs a punch, sounds great, looks great and all I ever do is change the fuel filters. I store it over the winter months and it has always started in the spring without any drama whatsoever. I don't idle it in the garage every Sunday or any such. Just a good tank of gas and put the battery on a charger. In the old days I didn't even do that and with no real drain in the old cars it would still have enough juice to fire months later.

I drive it recreationally, including around town, across town, and up to +9000' on perfect, dry as a bone, bluebird ski days, without any real complaints except on real hot days in the summer when I could probably use some phenolic insulators. I compensate by going easy when temps get up towards the upper 90's.

What would PMO's do for me that isn't already being done? To get the most out of either will probably need an AF gauge but do happy Webers have room to improve? Or am I just easily satisfied?

[Joe Bob]

Carbs are ALWAYS temperamental. If you have gone as long as you have w/o adjustments or trouble you are lucky.

That being said, PMO has done a LOT of changes to the basic design. They should be an improvement but nothing like going to ITBs with a fuel management system. PMO makes them as well.

Go to the website and fax your questions....I don't think he answers the phone or emails....still. %^b

[Jim2]

It sounds like your carbs are working well. If your AFRs are in check then there is not much to be gained from PMOs unless you increase the choke size but then you could do this to your webers as well. However, larger chokes that will contribute to top end power will take away from bottom and mid range torque. You don't say what displacement your motor is, this would help get opinions from others who have been down this road.

That is a really nice looking 911!

[Jesset100]

But when you do I get dibs on the Webers

[rbogh901]

Thanks Jim. It is a 2.7 liter engine with S cams.

[911_Dude]

If they are working that well, why mess with it? I have a 2.7 with Webers and Solex cams. Paul Abbott went through the carbs last year. I couldnt run better. If they are right they are right.

[wayner]

I don't know much about this but I thought the main benefit of PMOs is that they are available new

[RWebb]

nope

the PMOs have dozens of improvements and are aerospace level manf'd -- search on PMO for more info

[1QuickS]

Typically PMOs would be the way to go if converting to carbs and you don't have a set of Webers/Zeniths already. If you have an early car without Webers then, for originality the Webers/Zeniths would be preferred unless you intend to make modifications and don't care about "period correctness." If you already have Webers then you are bucks ahead since buying used carbs will not get you good condition ones and they will not be jetted for your application. The cost of sourcing and installing Webers would include: re-manufacturing to return them to good condition plus acquiring manifolds, linkages, air filters, etc. The total for this path will end up costing more than a set of new PMOs that come with everything you need for a bolt-on installation.

When reworked, Webers are reliable and efficient carbs. The PMOs may have a performance edge in total HP potential but unless you are hunting maximum HP then this is probably academic. Webers are limited to 46mm throttle bore size so for very strong 3.2 and larger engines the 50mm PMOs would look pretty attractive. The 46mm Webers are scarce but they can reliably created from 40mm bore diameter versions to be anything from 40mm to 46mm.

Another issue with sourcing used carbs is the variances in progression circuit design and how that affects transition performance; with the Webers it is easy to determine which model you have since they are well identified. However the Zeniths do not identify the earlier versions from the later ones and only a close inspection will provide the answer.

As for the quality of PMOs vs. Webers or Zenith: all are of highest quality manufacturing and materials. PMOs are an evolutionary product, their improvements over previous carb designs take design details from Weber IDA, Weber IDA3C and the Zeniths designs, adapting them for better manufacturing efficiency and correcting design deficiencies of the earlier carb offerings.

[DanielDudley]

You have hit the sweet spot in Porsche ownership. Stay there.

[rbogh901]

I think the PMO product is very nicely executed but can see how some, including myself, would rather run the classic Webers, if, and this may just be me, if they aren't leaving too much on the table. Looking at Paul's work is impressive.

As for temperamental, I have not had that problem. I think for a time I had trouble sorting out electrical vs fuel until I got rid of my points and installed the Pertronix. How does that saying go? 90% of fuel problems are electrical?

Now I'd like to get some objective insight into what performance advantage is realistic, assuming a good set of Webers vs. a good set of PMO's. While most PMO's are newish and look great, there is a range of what you see in Webers, everything from sad 45 year old dusty metal to meticulously maintained and highly functional works of art. Obviously replacing a bad set of the former with a new set of the latter is a foregone conclusion. If I had trouble with the Webers and couldn't get it straight that would be another thing.

In no way am I trying to downgrade the PMO product which I think looks fantastic and functions just as well. I'm saying maybe Webers have been short changed when poorly set up and in reality can match or come within a fraction of the performance of the PMO carb setup when compared apples to apples.