1) Will the PMO carbs fit my Zenith or Weber
Yes. All the bolt patterns are the same. Naturally, 40
mm carbs are for 40 mm manifolds,
2) Will the PMO carbs work with my CIS cams?
Yes. The early CIS cams (’73-’77) are limited but
still allow the carbs to produce
more horsepower. The later CIS and Motronic cams (’78
and later) are actually excellent cams for
3) What about my exhaust system?
The early style exhaust through ’74 is excellent.
From ’75 on an early style
exhaust, such as the SSI heat exchangers, is a necessity.
The size of the exhaust system is
extremely critical. If headers are used, we recommend
1-1/2 o.d. through 3.0 litre and 1-5/8" o.d. on 3.2
and up for street cars.
4) What about ignition systems?
The stock CDI ignition systems will generally work
through ’77. The early cars (’65-’68)
will need to add a CDI ignition. From ’78-’83 the
distributors need recurving. Check with
Barry at IAE.
5) What about my air conditioning and power
Provisions for both are included in the kits. On the
50mm PMO kits, air conditioning is
not an option because all manifolds for the 50mm carbs
are tall. The exception is if a whale tail is installed;
then the 50mm carbs can be used with
6) I have PMO watershield air cleaners on my
Webers (or Zeniths). Will they fit
the PMO carbs?
Yes, except for the base plates. We will include new
base plates at no charge when PMO
carbs are purchased.
7) What kind of performance increase can I
This depends on the condition and type of engine. PMO
carbs will outperform Weber and
Zenith carbs. The increased performance over mechanical
injection is usually the result of the
mechanical injection running too rich in
the midrange (which is almost always the rule). The CIS
and Motronic engines need changes in
the ignition and exhaust systems for the PMO carbs to
work properly. When these changes are made,
substantial increases in horsepower
are common. Full-on race engines frequently achieve 100
horsepower or more per litre. For
instance, George at Midwest Eurosport reports 320 horsepower
from a 2.8 litre race motor on their dyno. This engine
runs 46mm PMO carbs.
8) Are spare parts and rebuild kits available?
Yes. The PMO carbs will never have to be rebushed
because they have ball bearings on
the throttle shafts.
9) What parts are interchangeable with Weber?
We manufacture all the parts except we use Weber jets,
floats, and viton float needle valves.
To fine tune the idle circuit, we manufacture the
idle air jets.
10) What kind of Weber jets does the PMO carb
The same as the IDF Weber. The main jets, emulsion
tubes, and air jets are the same for
the Weber IDF, DCOE, 2 bbl 48 IDA, and the PMO. PMO
carbs use the IDF idle fuel jets. As
already mentioned, the idle air jets are manufactured
11) What is included in the kits?
Everything needed. Please check our question and answer
sheet and check-off list seen
elsewhere on our website. We make over fifteen different
911 manifolds to properly fit the PMO carbs to your
12) Are people happy with PMO carbs and
Yes! See our list of Testimonials.
13) How do I order?
See our Purchase page.