To rebuild my Weber's or buy new PMOs, that is the question.....

svonkampen · 06-25-2004, 03:39 PM

Well,

Here it goes,

My 1968 911L is my daily driver......My mech thinks that since it is my main ride......it would be better to buy new PMO carbs than to rebuild the Weber's........Rebuild would cost 850.00......PMOs would run 2400.00....His reasoning is that no rebuild would be as good as a set of new carbs.....He also claims that PMOs are actually better than the Weber's........For me, reliability is key here.....I drive this car everyday, not just on Sundays.

Opinions?

SvK
1968 911L

Garrett · 06-25-2004, 03:53 PM

If you can do it yourself, you can buy a weber rebuild kit for $120 from Pelican and spend your dough elsewhere. Then again, if you can spend 2400, new carbs would certainly be better than 38 year old ones! I think PMO's are the same except the window on the float bowl...

svonkampen · 06-25-2004, 04:01 PM

hmmmm

So,

Anybody out there with PMOs?

btw,

thanx Garrett

SvK

RoninLB · 06-25-2004, 04:19 PM

well it kinda comes down if you need only real good enough or the highest level that 911 carbs can attain.

fwiw if I decided on the webers I'd probably sell them and buy the used IDS model. I was hanging with Harry Bieker from Bieker Engineering for a few days around a camp fire and I discussed the IDS with him because I has a set in my closet. and he said there is a different machined area of the carb that he's produced to replicate it. meanwhile the rebuildable needed price of the IDS is within appx $200 of the IDA.. So if you want to rebuild maybe confirm my info with Bieker.. oh btw he muilds exotic carbs for racing. and personally either the IDS or PMO would be very cool.

RoninLB · 06-25-2004, 04:19 PM

Quote:

Originally posted by svonkampen

Anybody out there with PMOs?

yes

svonkampen · 06-25-2004, 04:25 PM

thanx Ronin

svK

svonkampen · 06-25-2004, 06:54 PM

bump

jluetjen · jluetjen's Garage

$2400 is an awful lot of money. I don't see how a rebuilt set is any worse then new. The one condition is the throttle shafts. I just had Eurometrix R&R my bodies, rebush the shafts and R&R the throttle plates themselves. Matt also highlighted some issues which I would never have spotted by myself which I've fixed. I don't know how they will be any worse then new except for the petina of the bodies.

As far as the IDS versus IDA's, for normal street use I don't think that there is any benefit to the IDS's (which I have). It's not even clear to me that the IDS's are a benefit for use on engines with S or wilder cams. The biggest difference is the high speed inrichment circuit. Given modern fuels and the wide range of emulsion tubes, I haven't seen any clear justification for the extra circuit. With 40's, the general constraint at high rev's is getting enough air through rather then enough fuel (much like CIS's).

Does not mean that I'm throwing mine out??? No. But since the J-tubes from the high speed circuit don't reach over the tall secondaries (which address a far more substancial problem between 3000 and 4000 RPM when using full race cams), I'm just going to block that circuit off for the time being until after I dyno the motor and determine that there is a lean problem at high RPM's.

Mukilteo911 · 06-26-2004, 08:06 AM

Whatever you do, do not toss your old carbs. They can be recycled into a good running set. And as a secondary note, several of my friends run carbs as well as myself everyday and I love them.

Third note is, if your considering replacement also consider a premade EFI system. You can buy them, they will work great and get killer milage. Do a search on the site on the EFI stuff and read up on it some, gas is only getting more expensive.

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by Garrett
I think PMO's are the same except the window on the float bowl...

Nope - they look similar, but they are a totally new design based around the old Weber carbs...

-Wayne

Randy Webb · 06-26-2004, 10:35 AM

I think you need to find out exactly what changes Richard Parr made to the Webers. There's the new way the shafts sit, and the fuel feed to the whole carb, and a bunch of stuff I don't know.

IF the other stuff is something you cannot get close to w/a rebuild,
AND it is worth the price increment,
THEN (execute car purchase subprogam).

svonkampen · 12:39 PM

Wayne......

what is your opinion on installing PMOs to increase reliability of a daily driver over rebuilding my Weber's?

My mech says that even with a rebuild the Weber's are real finicky and need constant adjustment, where as the PMOs are a much more straight forward deal......

His reasoning seems sound......"Your Weber's are 35 years old, PMOs are brand new and an improved version of the Weber design"

SvK

Schuey · 06-26-2004, 01:16 PM

talk to Steve at Rennsport Systems, www.rennsportsystems.com he's what I would call an expert on this...

my 2-cents is go with PMO's and sell the webers on eBay or here...

Oldporsche · 06-26-2004, 02:01 PM

I think I would go with Eurometrix or Bieker engineering or someone that specalizes in redoing the Webers. (Not Motormeister) The big thing is throttle shaft wear. They probably need to be bushed. I believe that there are oversized shafts available for these carbs. The throttle plates wear the bores too. These things aren't enough to discard the webers.

I have a set of 35 year old ones on my 2.7L. They are very stable and in good shape. I think that they are a little rich on the bottom end however the msd takes care of that part of it. If I ever wear them out, I have a set of IDTP's (found on 914-6) in the basement ready to go.

If you could get another 10years of use out of them, what would you care?

If I were building some KingKong motor to run on carbs, I would look at the PMO's or maybe some 46's.

David Duffield

911pcars · 06-26-2004, 02:25 PM

"My mech says that even with a rebuild the Weber's are real finicky and need constant adjustment, where as the PMOs are a much more straight forward deal......"

Svk,
I don't find Webers to be finicky at all; they don't need constant fiddling unless there are some gross setup, adjustment or wear issues. If the fuel/air passages are clean and the throttle bores are not worn, there shouldn't be a problem. A repair shop's point of view might be a little different than an owner's. Just mho.

Among other improvements over the Webers, PMO's version has ball bearing-suppported throttle shafts, a fluel level inspection window and inverted (drop down) float assemblies. Renewing the throttle shafts and rebuilding rebuildable carbs might be a grand. Is the price difference worth it to you?

Sherwood