Help with buying PMOs

[theorangeperil]

I'm seriously considering retiring the Webers for some PMOs.
I've been told I I just need the carbs themselves as the manifolds and airbox from the webers will be useable. I know the jetting.
Should I go straight to PMO and buy direct or is there a better way? I hear their service is great, but are there any tips or anything to keep in mind?
How to handle import, customs etc? I have pals in LA who could help if it makes sense.
All help appreciated...

[shoestring7]

I can't think of any reason not to go direct to PMO. Richard Parr is very helpful, and the kit contains everything you need. The £/$ values help at the moment and he will 'adjust' the invoice value for customs if that helps.

The only thing I would say is that once they're fitted you should budget for a rolling road session with someone who knows their way around Webers to finalise the jetting etc.Made a big difference to mine.

C.

[PMNorris]

I fitted PMO's on my SC engine. I ordered mine through Jean Buser in France, but got lots of advice from Richard before, during and after. I didn't originally go with some of the recommended modifications (recurved distributor, MSD, hotter plugs) as i used a different 3rd party ignition system, but am now doing that as it doesn't run too well and 3 different specialists have failed to get it to run properly. One of these was a Weber expert who told me he wouldn't tune PMO's. Also, the lack of cold start makes it hard to start here in Switzerland. Despite all this, i'm happy with the result so far, and hope the latest ignition mods will finally get it to run perfectly.

[40 scout]

Don't be put off Peter, I too went direct, the best carbs I've ever had, great starting hot and cold and crisp running - very very good

Richard is very helpful.

Ps mine delivered to hotel in NYC and brought back to uk as hand luggage !

Steve

[911hillclimber]

Brilliant carbs, dumped my Webers for a big set of PMO's on my 3.2 running a 2.7 distributor.

Many RR's shy away from triple carbs as they are unknown.
They use Weber DCOE jets so easy to tweek.
Richard Parr is so helpful too, nothing is to much trouble.

In the end I tuned mine myself at home! (not hard to do)

They are just so better engineered in detail than webers.

Buy Quality once.

[Lightweight_911]

I'm going to kick against the trend by sticking up for Webers...

The PMO's might be an improvement but I've never had any problems with properly rebuilt/set-up Webers on the cars I've run them on.

Triple-choke IDA's/IDS's/IDT's have been successfully used on thousands of early 911's, 904/6's, 906's, etc & there's plenty of expertise/parts out there.

[sladey]

Just re- read the original post, and you've already got webers. The PMOs are replicas of webers, are they not? Admittedly well-made, but replicas to satisfy a shortage of supply.

Might a better route be to have your webers refreshed? Throttle spindles reamed etc. Why are you wanting to change the webers?

Not being awkward but sometimes it's good to question the question

[911hillclimber]

A balancing point of view is good!

I went to PMO to correct a carb issue I had on the hillclimber on the 40's I had with the engine, not really big enough for a 3.2.
The PMO web site gives all the reasons they came about and the improvements they made at the time. I felt those improvements were worth it.

Cleaned and rebuilt (admittedly DIY) my webers would not run right and a local RR man refused to deal with them as the jets were special and not in his draws.

All webers are old now and some evil and some great.
If you want to skip the grief of getting them right then PMO are your option. I had spent months trying with the webers so felt like Keith Seume does right now...

To buy another set and have them pro re-furbished was the same as PMO's.
I bought mine 500 miles old because the seller wanted originality.
My old webers ran as sweet as a dream on his 2.8.

[40 scout]

My choice was original CIS (spectacular backfires on starting !) or PMO - took about a second to decide

Steve

[911hillclimber]

My webers always popped and BANGED in that magnitude all the time, even after Bob had tweeked them.

The PMO's don't and that's after even I had tweeked them with a balancer and colour tune.

iirc the PMO's have 3 fueling circuits, slow, med. high and the webers 2, slow and fast with a difficult transition?
Stand to be corrected.

[MikeB]

I had PMOs on my 2.2S engine, they came unused from Nick Moss jetted for a 2.5 iirc, emailed Richard Parr told him what I had and he swapped out all the jets for free. The set-up he sent was spot on, and helped sell the car, as the buyers said it was the first one they had seen start up and not pop and bang.

Basically, unless you want originality, I would say they are a terrific replacement system, but if you have a set of Webers it might be worth your while seeing how much it would be to get them rebuilt, as there used to be a bit of a delivery time for new PMOs.

[gridgway]

on a separate note, buying stuff from the US with a UK credit card gets expensive. The exchasnge rate is poor and there is the non-sterling transaction fee. Just spent about £2400 with a US company and the fee was £70. Forewarned...
Graham

[fetuhoe]

There are a couple of issues with Webers that can be corrected with some effort.

They shouldn't really pop and bang and this is often due to problems with the galleries being partly blocked and the only real way to deal with the issue is to take out the lead plugs clean them thoroughly and re-plug.

To say that there are only 2 circuits is not strictly correct.

The PMO has basically the same design as the IDA with the exception that the idle jet air corrector is a fixed bush in the Weber and is a 'tuneable' jet in the PMO.

In effect the idle jet can and does affect the progression circuit of both the Weber and the PMO to around 2500 to 3000rpm depending on the exact set up.

The fixed bush in the Weber has been selected to suit a particular venturi/idle jet and the progression drillings in the carb body and is pretty much correct for an individual set up. The PMO offers a better range of adjustment and this eliminates a potential stumble.

This means that the IDA. ITD, IDTP etc all have slightly different progression drillings and slightly different idle jet air corrector bush.

If you fool around with the engine set up it is quite difficult to prevent a 'stumble' somewhere in the operating range due to the size of this bush.

A good example of the problem this part of the circuit can cause can be found on the 40DCOE.

The Spanish manufactured 40DCOE151 carbs only had 2 progression drillings in the bore and this meant if the idle was set correctly they would normally produce a flat spot at around 2000rpm. If you 'flooded' the idle you could eliminate the flat spot but the idle would be 'lumpy'. For race engine that used WOT this wasn't much of an issue but on road cars was a pain.

Early Weber 40DCOE18 carbs had 3 progression drillings and didn't suffer this problem and we made a jig and drilled the extra hole in the '151' and solved the problem.

In the same way it is possible to modify the idle air corrector on 40IDA type carb and make it tuneable and we do this mod as part of a rebuild operation.




Selecting the correct jets, idles, emulsion tubes etc is not too difficult and jets are not vastly expensive and we have a very broad selection available along with 32, 34 and 36mm venturis.

[911hillclimber]

Interesting!

The pmo have screw-out blanking plugs so you can open the drillings and clean and re-seal without the lead bung to do.
It is these details I like so much on the PMO design changes, but admittedly this is not a process you do every day on the carbs...

At the time I felt the 40's were too small for the 3.2 and 45's were non existent (then) so PMO were the only option.

I wonder how many are on other engines that use triple webers?

[fetuhoe]

I believe that a single 40IDA3C Weber carburetor was first used on the 1962 Lancia Flaminia 2.8 liter V6.

Porsche first used a 46IDA3C on the six Porsche 904s outfitted with the 6-cylinder Porsche 901/20 engine in 1963 and they were fitted to many of the 906s used by both the factory and Private entrants.

They were also used in 46IDA format on the 911R and 2.5ST

Feb 1966 the Webers 40IDA became OEM supplier for the 911 production cars.

The Lamborghini Miura displayed at the Turin Salon in December 1965 used 40IDL3Cs.

They were also fitted to Ferrari 365 and 512 BBs, Renault Alpine A310s, v6 Peugeot 504s and finally the V6 Talbot Solara.

The 46IDA were, as far as I know never fitted to any production 911s and interestingly the new pair that I have measure at 45.5 rather then 46.

We have been boring them out to 45mm and fitting plugs in the progression area to be the same as on the genuine 46IDA and fitting the tall auxiliary venturis.