Weber Vs PMO what's the Diff

[matty74]

I have a pair of IDA3C webers 40mm I want to get them rebuilt.

But I have been thinking maybe I just spring for a new set of PMO's.

I'm hearing PMO this, PMO that, and how damn good PMO's are which is mostly coming from this forum and some porsche guys here in Australia, who rave about how good they are.

Could I have my webers rebuilt with soem of the improvements PMO made on the weber design? and get close to PMO reliability.

Is it worth the extra $$

what do the experts reckon?

[Steve@Rennsport]

Matt:

A Weber carb in perfect condition can run very well,...

PMO's addressed all the shortcomings of the 54 year old design such as:

1) Sealed ball bearing mounted shafts (Webers use teflon bushings)

2) Center pivot floats to reduce/eliminate fuel starvation in hard corners on modern tires

3) Vastly improved idle & progression circuits for better part throttle response and fuel economy

All things being equal, I'd much rather have the modern PMO over any Weber (and I have 40 IDA's on my own car).

[randywebb]

re the other question, yes at least some upgrades can be done to the Webers -- I don't know which, but either Steve can re-post or you can call R. Parr

[JP911]

I've never owned Webers, but I'll throw another recommendation in the pile for the PMOs. I've got 46s on my engine and I absolutely love them. They're meticulously constructed and the complete kit comes with absolutely everything you need for installation.

[TWork]

Jon, I'm waiting on my set of PMO's to arrive. Don't want to hijack the thread, but any thoughts/tips on the install? I'm putting them on a 3.0 SC motor.

T.

[rusnak]

The diff is that Webers can wear out in the throttle shaft, and PMOs have ball bearing shafts. Otherwise, the only other diff is that Webers are becoming rare like museum pieces.

[matty74]

Can webers be upgraded to the balbearing throtlle shafts??

[rusnak]

Bump for Matty's question.

My 914-6 and I want to know!

[jtkkz]

I have PMO's on my '71 very nice carbs

As far as better fuel economy hmmmm not sure about that my car drinks gas

[randywebb]

there is some throttel shaft upgrde - not sure if it is ball bearings or what

- you really need to call the experts

[Grady Clay]

Guys,

I have had both.
40 & 46 Weber and 40 & 46 PMO

If I were to buy one today it would be a PMO unless for show originality. The PMO addressed most of the flaws in the original Weber design and production. The PMOs are also far more serviceable today.

Best,
Grady

Good 'ol Porsche Mail Order.

[911pcars]

Originally posted by matty74
Can webers be upgraded to the balbearing throtlle shafts??

Eurometrix and Biekers can install new bushings in the housings. Not sure about ball bearings.

You have to weigh the cost difference between new PMOs (~$2500) and fixing a pair of Webers you already own.

Sherwood

[JP911]

The PMO install is pretty straightforward, but there are a few issues you need to be aware of. If you're not too far away (outside Sacramento?) I'd be willing to help out.

1. the openings in the fan shroud for the CIS runners are smaller than the insulators/spacers that come with the kit (at least they were on my car) and I had to enlargen them.
2. You need to install longer intake studs, but my kit did not come with them (it's supposed to). Fear not, the intake studs come out easily.
3. The throttle rod coming from the trans up through the sheet metal was too long. I cut it and then used a small block with pressure screws to adjust it to the desired length.
4. The hole in the engine tin that the throtttle rod comes through needs to be enlarged so that the throttle action is unemcumbered.
5. The hose clamps for the fuel lines are crap.
6. Take your time when setting up the linkage to make sure that you're getting full throttle. The trick is in adjusting the length on the rods on each carb
7. Follow the instructions on the PMO site very carefully and consult this post as well: Weber rebuild
8. If these are going on a car with non-boosted brakes you may need to find a plug to block of the vacuum source. I used a brass pipe plug with teflon thread tape.
9. BE CAREFUL when installing and tuning as it's just too easy to drop something into the heads.
10. Be patient when it comes to tuning.
11. Have Fun!!!!

[rusnak]

Matty,

I thought your '74 came with injection. Anyway, I have a leaking throttle shaft on my '70 914-6 Webers. I am sort of in a preservation mode on the car now, since everything is all original. I love the PMOs but they are so darn expensive!!

[matty74]

Yeah currently it has CIS but I'm going to rebuild to a 2.7 with JE pistons GE 60 Cams and webers, of which I a have all the parts.

The webers will need a rebuild but if possible if they can be upgraded so they can have near PMO reliability and performance.

[rusnak]

ah, hence jp911's excellent post.

I guess you don't want to recalibrate the injection to 2.7 specs, or use the cams that are compatible with the injection.

[TWork]

Thanks Jon. I'm about 30-40 minutes East of Sac on 50. I'll definitely keep your tips in mind. Thanks a bunch!

[matty74]

No the cams and CIS are going

BTW: JP911 thanks for the offer really generous, head west the other side of the planet take a sharp left south until you hit a big patch of desert.