WEBER FATIGUE/DILEMMA IM6

Just a blurb about my carb performance issues that a short few might find some interest.....maybe as a flat six issue with 3 barrel Webers.

After a few short months, I am tiring of the slight flat spot in my carbs.....after much intense research about WEBER 3 barrel carbs and their origin(for Ferrari and NOT Porsche) and with discussion with Paul Abbott(WEBER GURU and purist) I realized that I need to fix this! Looking for smoother ride and rid that last bit of hesitation!

There is an inherent deficiency in the below 2500 RPMs in the Webers relative to many performance flat six motors. For the last 20 years, using the Weber as a starting point, Richard Paar, founder of PMO, essentially re-engineered every short coming of the Weber 3 barrel and enabled a variety of sizes of needles/jets/etc. to match any build profile.....clearly a far superior product with kudos to Weber for the initial invention. Paul Abbot, the self admitted Weber purist(proprietor of Performance Oriented), who remanufactures/reconditions old worn Webers, agreed that the PMO is a superior product, despite making his living as a Weber "guy". He, like many others, cannot let go of Weber "LORE" despite PMO being a far superior and applicable carb, would NEVER put a PMO on his car(full well knowing its a better carb). He even suggested buying the PMOs and selling my Webers to fund the purchase as a sound pursuit and he is busy: his next opening for remanu/recon is July 2018 and the full remanu/upgrade process approaches $3500 which is close to the PMO buy.

I had some initial concern about the Weber/original/historic factors when I realized that as a replica, having a 2.7 flat six with a 5 speed has already violated the 50s speedster heritage and I might as well upgrade. Truly, driving the car is amazing, so much so that with all that HP and torque in a 2300 pound car, the low RPM short coming was pissing me off as much of my driving is local, under 55 MPH stuff, and I would prefer smoother acceleration. Some might say spark is your problem, but the research and history clearly supports the carbs(especially old/tired carbs with its inherently weak skill set in low RPMs) is the problem although PMO recommends a recurve/rebuild of distributor(Barry Hershorn of Distributor Lab) to fully complement the new carbs.

The internet is chock full of guys who remove their old Webers and/or fuel injection for PMOs and the reports are 99% in the plus column despite the almost $4500 wake up call. In any case, the weakness in the low RPM range of many 2.7/3.0/3.2 is largely eliminated(theoretically) along with an increase in horsepower. The two things that create explosion are fuel and spark and each motor's profile has an optimum relationship with the two throughout the RPM range. Of course, fuel injection, with programmable crank fired ignition is most desirable although for some reason, greater horse power and torque are achieved with PMO carbs despite less efficiency and poorer gas mileage, although most Porsche guys looking for performance/MAX torque-HP do not give a hoot about gas mileage. I will trade mileage for performance and the much reported lower PMO maintenance needs and considerably higher predictability of performance.

Looks like PMOs right after the New Year with distributor rebuild and sell off the historic Webers to a purist. I did not come to this lightly without extensive readings on both/three sides of the aisle(Weber vs PMO vs EFI). I certainly will not be racing or need full mapping of my acceleration/performance profile but my carbs do need rebuild and the smart choice "appears" to be the PMO route. Time will tell and and will report back in a blurb to interested folks. 

My mechanic, 3.8 crank fired/twin plug/PMO 50s/400hp/911, pointed out that it could cost me $5K to bring my car from 92% to 98/99% and is it worth it? I love this car and its the last car that I will buy outside of an 89 Explorer with 238,000 miles to get around town, should I need basic transportation. It IS worth it to me....(no scream intended in use of capitol letters)

Original Post
Stan Galat posted:

Banzai,

There's no comparison. PMOs rock. 

Apparently.....I have read everything on line since 2002 and as much as I tried to be loyal to the infamous WEBER legacy, it was a no brainer. They laid the foundation but stopped at third base..........and PMOs will bring me home( how milky is that?).

When a Weber purist admits that PMO is better, despite his entire life and business wrapped around Weber, its time. Ciao

I don't think the previous owner of your IM6 ever drove the car hard enough - or even just drove it enough - to recognize the issue of the flat spot.  In addition, I don't know if he would be able to recognize the issue with the flat spot even if he did drive the car enough.  He really did not seem the Speedster type.  I got the feeling he was more comfortable driving 'one of his many other cars'.

So, I guess that's why you have inherited the carb issue.  Mixed in with the overall price of you car, a set of new carbs is not all that bad, and then it's happy motoring from then on.

Bob: IM S6 posted:

I don't think the previous owner of your IM6 ever drove the car hard enough - or even just drove it enough - to recognize the issue of the flat spot.  In addition, I don't know if he would be able to recognize the issue with the flat spot even if he did drive the car enough.  He really did not seem the Speedster type.  I got the feeling he was more comfortable driving 'one of his many other cars'.

So, I guess that's why you have inherited the carb issue.  Mixed in with the overall price of you car, a set of new carbs is not all that bad, and then it's happy motoring from then on.

You are absolutely correct......I considered it a bargain and expected to drop another 10K so I am OK with it. Whatever it takes to get it right is fine....just wanted to share the ride as others have and  will find quirks along the way that need similar management... whether its Chinese parts, or bogus ignition coils

 

I think if it were me, I'd at least try a simple test to help confirm it's the carbs.

Try advancing the timing about five degrees from where it is now and go for a short, gentle drive (don't rev it very high). Is there any change at all in the flat spot?

If not, the carbs are probably the guilty parties. But if the flat spot does change at all, for better or worse, maybe look into tweaking or replacing the dizzy before messing with the carbs.

After the test, you'll need to set the timing back to where it was (assuming it was right to begin with).

This is not a definitive test, but it may give you another data point, and before investing that kind of coin, I'd want all the data I could get.

 

Sacto Mitch posted:

 

I think if it were me, I'd at least try a simple test to help confirm it's the carbs.

Try advancing the timing about five degrees from where it is now and go for a short, gentle drive (don't rev it very high). Is there any change at all in the flat spot?

If not, the carbs are probably the guilty parties. But if the flat spot does change at all, for better or worse, maybe look into tweaking or replacing the dizzy before messing with the carbs.

After the test, you'll need to set the timing back to where it was (assuming it was right to begin with).

This is not a definitive test, but it may give you another data point, and before investing that kind of coin, I'd want all the data I could get.

 

I have a master mechanic, who races, and, has been an elite Porsche Doc for 32 years. He has done all of the above AND within 3 minutes of introducing the car to him, told me what I now know: he warned me that the carbs and the dizzy were a potential issue after a 5 minute drive. He tuned the car, advanced the timing and warned me that it will hold the tune for 4 weeks if I'm lucky....he could tell that there were air leaks, bushing issues, AND after 30 plus years of fiddling with Webers, knew what ultimately would need to be done......at the same time explaining the Weber purist mindset and the absolute engineering remedy of PMO. There is a reason why Weber stopped making 3 barrel carbs AND moved to Spain.....the Porscheophiles turned on them and the PMO product blew them away.....it was PMOs for brute HP/torque or EFI for full electronic management and scientific efficiency.....or live with the Weber doodles.

By the way, there was no more advance left on my dizzy after the tune.....the carbs were the wrong ones or should I say inadequate for the 2.7RS profile/cam/port size/etc. to begin with and the dizzy could not remedy the issue in any reasonable manner. It was what was readily available ay the time of build and as my mechanic suggested, got a grade of 89 to 91 but would never be 97 to 99% without the PMO upgrade. If I wanted perfection, it would cost $5000 plus for a 97/99 or triple that for PMO/crank fire/ twin plug/12 coils!

I'll take the 97/99 with new PMOs and a remanu/recurved dizzy to fit the build and eliminate all of the Weber doodles. Appreciate the suggestion, indeed, but have already been thru the process with thorough explanations at each stage of failure. I must say, in all honesty, this machine kicks big ass the way it is.....I would just like to get rid of that last bit that represents the cherry on top of the whipped cream. It just isn't a perfect ice cream Sundae without the cherry on top and both Webers and PMOs cost big coin.......gotta do the time when you do the crime

I have a pal who is a STEREOPHILE nut: he spent $18,000 on speaker wires, $10K on a power conditioner and $8K for a turntable CARTRIDGE for a $60K turntable. He has almost $300K into his stereo so that he can enjoy "PURE" sound, the way it was recorded without any false electronic overlay(LOL). Good for HIM, indeed, but I'll take $5K for carbs any day over $18K speaker wires.

To each his own and the great fortune of living in the USA

I would probably have the dizzies fixed first and then try to see if the carbs can be tuned after all have you driven that car for a year yet?  I don't think so.  It is just that maybe a few forums or another opinion might develop with refurb/new dizzies. 

There may be other expert P mechanics that could comment. 

Anyway, I like to take it step by step before going on a parts change frenzy. 

Problem with those wires is the wires inside the cochlea become defective with age, a condition called presbycusis so .... it might be satisfaction of the heart but the ears will not be able to discern the change in sound and as a friend Benzai, your job, if you choose to do agree to this mission, is to support his dilusion...  

IaM-Ray posted:

I would probably have the dizzies fixed first and then try to see if the carbs can be tuned after all have you driven that car for a year yet?  I don't think so.  It is just that maybe a few forums or another opinion might develop with refurb/new dizzies. 

There may be other expert P mechanics that could comment. 

Anyway, I like to take it step by step before going on a parts change frenzy. 

There are many forums: Pelican, Rennlist, PCA, 911 REGISTRY.....all have blurbs going back 15 years with the exact same Weber/flat spot issues! All(95% plus) remedied by PMOs after switching from tired/inadequate Webers with comments by top guys at RENN/Patrick Motorsports/etc.....you can read them all. Virtually IDENTICAL problems remedied with upgrades in PMO and recurved DIZZIES.....the literature all backed up by the GURUS of Porsche performance. I did not take this lightly without turning every stone and every angle by the most qualified guys in our hemisphere. 

Jim Kelly posted:

Audio nuts have lots in common with car nuts: very strong opinions about cost, quality, the existence of certain problems, how to define them, and the possibility of fixing these supposed problems by throwing money at them. 

Very true....my buddy explains to me how each component of his system, and he has 19, including separate tuner, DAC: digital analog converter( this corrects signal path 300 times per second),  has its own dedicated power circuit from his house panel to prevent distortion, and his turntable sits on a $10K table to ward off vibrations that are transferred through the chassis of the turntable that might reverberate back into the phono cartridge and alter the sound! God bless him and his music. I guess it is similar to spending $1000 on a WEVO shifter because of the very positive "click" and firm seating through out the gear pattern, although I can vouch for feeling the click!

But yes, he spent more on his speaker cables(for one set of his speakers and he has 3 pair) than the cost of some speedsters. Stereo madness I presume.....

Robert M posted:
Will Hesch posted:

I'm so comfortable on this forum that it's easy for me to admit, unabashedly, that I don't know what the heck a PMO or a WEVO are...

...and not knowing isn't changing my life one ioda...

Me either but I do know that WEVOS wobble but they don't fall down.

 

This is excellent on so many levels...

Stan Galat posted:
Robert M posted:
Will Hesch posted:

I'm so comfortable on this forum that it's easy for me to admit, unabashedly, that I don't know what the heck a PMO or a WEVO are...

...and not knowing isn't changing my life one ioda...

Me either but I do know that WEVOS wobble but they don't fall down.

 

This is excellent on so many levels...

Will, your bank account likes you so much more that you are not in the know for PMO AND WEVO's.  It's a whole other level of madness

IaM-Ray posted:

Benzai being convinced that this is the solution  is what you need to move forward with the madness ..:. Then we can support you in your decision

I am as eager as possible to fix the problem and lose that last bit of missing "giddyup" from the power curve. It's like having a supermodel girlfriend that has a big pimple on her butt that only you can see in the hot tub......she's amazing and world class, but you know that big carbuncle lingers and it just wont leave your conscience. If I end up drubbing the fix...I will admit my fooolery  and do a "better luck next time"

ALB posted:

Whoa, $4500 (US- that's like about a cajillion Canadian  dollars- holy sh*t!) for new carbs; how much for the recurved/rebuilt distributor? This is what happens when you up the game with real Porsche stuff in a plastic Speedster... 

you are right....but half of the supercars around(Lotus/Alfa/Ferrari/Lambo/McLaren) are more fiberglass(plastic) and carbon fiber than metal! But I must say that its worth it.....I would hope that most of you get a shot at driving an IM6 as it is not a typical ride by any means. It handles like a low slung 911 go-kart and is as fast as a 911....but 1000 to 1500 pounds less in weight(depending upon the model). It is freakin amazing and I'm not just blowing smoke....210hp in a 2300 pound car with a strong flat torque curve is quite a bit different animal than 125hp/4 cylinder in a 2300 pound car. The suspension is all 911 also which adds to the experience.....not to lessen the value and experience in less powerful speedsters. But YES...the dollars are a bit eye-popping and another 5 to 700 for the rebuilt/recurved Dizzy.

Bill Prout posted:

I love my VW powered 2110 fake Speedster with 44 Webers that have no "flat spots"!

Just a point of information...the 3 barrel Weber was built specifically for use in early 60s for Ferrari. Weber only came on the factory Porsche 911T for 2 or 3 years.....as the earlier Solex/Zenith attempts were "doodie".....all other uses were by the "seat of your pants" applications by Porsche flat six enthusiasts. Unlike the 3 barrel, the 2 barrel 44s and others were purposely engineered for flat fours which is why they are considerably more predictable in your 2110. The profile of each 4, depending upon heads, cam, rockers, exhaust, pistons, compression, allow one to match up a given Weber/Kadron/Dell'o for use. Its not quite apples to apples and a simple remedy although PMO appears to have fixed the Weber 3 ill and theoretically all is well. I will know when I have fixed the issue or have taken a long $5000 piss down the drain.

flatfourfan posted:
Banzai Pipeline posted:

Yup, that's what I found too. 

Ever thought of something like JENVEY ITB's?

 

They are throttle bodies that require a full fuel injection assembly....the throttle bodies are just the conduit for delivering gas into the manifold/head but that is only 1/3 of the system. A full EFI system would be 12 to 15K or MORE including the throttle bodies, injectors, high pressure fuel injection pump! Also one needs fuel lines and labor costs as I have 8 thumbs and 2 bird fingers

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