Webers or PMO??

Hi guys!
I am collecting parts for a 2.0 Aluminium engine build for my 67S.

What would be the best carburators;

NOS Italien Made 40 IDA or 40 PMO?

NOS Webers ..

Neither…Go with refurbished Weber 40 IDS.

Efi, PMO, Weber in that order.

Thank you for your comments!

I bought the NOS pair with webers here in Norway and I also have an offer on a unused set of 40mm PMO with manifolds, filters and linkage for ca $5000 also here in Norway.

It is an early T aluminium case and I have 69S heads so will be a basket case engine anyway so I dont actually need IDS. But maybe put enrichment tubes in the IDA’s.

Most important is to get a pair of good carbs that work great.

The Webers Are stamped B9 which is february 1989?

Are all Italien Webers the same/same quality?

Where's the MFI in your triage 66S:) I know, not period correct but that's what I have in my 67.

NOS Webers are perfect. PMOs do not have ability to add High Speed Enrichment Tubes but the Webers can be retrofitted with little mill work.

The 2-liter engines used heads with an included angle between the valves that was greater than later engines. Starting in 1970, this angle decreased which flattened out the dome in the heads which aided flame propagation during combustion. The HSE Tubes enrich mixture at high RPM and engine loads which caused piston breakage and burned piston issues for the 2-liter 911S engines.

If you are considering MFI as an option then also consider Webers with twin plug ignition: lower cost and complication and no flame propagation issues and no need for HSE Tubes.

Expect at something like 180HP with Webers and 69S heads, 67S heads would drop HP by 10.

Aesthetically: PMOs are wrong in an early chassis. If you build a hot rod or large displacement engine for your 1974 or later car then put PMOs on it as you like.

Thank you Paul for great information!
I will not go MFI or dual ignition but keep it simple with 67/68S-spec.
And will consider enrichment tubes.
I have som early 40 IDF wich also have enrichment tunes, is it the same reason? (40IDF 22-25 and 30)

I’m installing Webers on my 70S, have 46 PMOs on my 2.5. The mfi will go in a box for the next owner. I once sold 2 sets of 69s and two sets of 2.4T mfi for $400 at Hershey just to make room in my attic. I don’t hate it but I don’t want to use it myself. I bought an efi conversion (X-Factory) and want to try it out, looking for 7-10 more mpg, cleaner emissions, gasohol compatible. Hotted up 2.0 motors really benefit from dual plugs.

Since Paul added to this perhaps a little advice? 69S motor with MFI of course. rebuilt to 2.2 single plug with Mahle's and machine work. Motor will go into RothSport sometime this spring when it stops raining. I'm dreading/expecting a recommendation for some linkage work. Per multiple advice I've only touched the air screws and decel switch according to the Rice paper.

66S, I do get 12-15MPG if I get on it. Perhaps 20ish if I loaf around. I don't really care about that since last year was <1,000 miles. I do have a non ethanol tank here but I'm lucky that way. I've got to say the MFI is fun. My friend with a 73.5/3.2 agrees same driver in my car would beat his downhill. His torque curve would win uphill. I do have Boxster brakes and a stiffer suspension than 1QuickS though...

Cool set up! MFI is great but expensive, I guess $10k in total?

Price I couldn't tell you, the car came that way when I got it, 1983. I'm guessing +/- 2K if the throttle bodies get rebushed. I have seen flame at night on a hard decel though. Deer, tourists drivers, joggers who think all black clothing is cool, not worth it anymore. Off to a PCA AX to see friends. I'll enter mine when we'll have dry weather. I did pull paperwork for the motor rebuild a while ago. Made me laugh, I don't think adding a zero to it would cover today's prices.

Kjell, I have tried both PMOs and Webers. My PMO's were new, and my Webers were 40 IDS and rebuilt to as-new condition by Paul Abbott.

Bottom line: the Webers worked better for my 2.0L (which is twin-plug). They were smoother in transition to the main circuit. If you get Webers, the high speed enrichment circuit on the IDS (versus IDA) model carbs is something I strongly recommend. On my car -- as I accelerate -- I can tell at ~5800 rpm when the extra fuel gets added to the flow from that HSE circuit.

The PMOs were fine, and I did very much like the PMO's fuel float level "windows" feature that the PMOs have and Webers do not. But the Webers are better for my car in terms of smoothness. So I prefer the Webers, especially the IDS version.

Best,
Andy in New Hampshire

Hello Andy and Thank you for your thoughts regarding PMO vs Weber!

I have landed on Webers and will possibly add the enrichment tubes if this is fairly straight forward on these late Italien carbs. Of course if I could trade these with a pair of IDS in great condition this would be best.

Btw, I would be very happy if you could send me a couple of pictures of your 911 in Aetna Blue(the original color?) to my email (kjelltbrekka@gmail.com)
Sounds like a great color for a SWB!
Thanks