40 pmo carbs

[spyderwerks]

Recent rebuild of 69 911T Engine to 2.2 E Specs.,using 2.2 P&Cs & reground T cams to E . Replaced the 40IDAs with 40 PMO's.

Herein lies the question, What have those who have the same config. done to optimize the PMOs. They are equipped presently with 32 venturies, 130 mains, 55 idle, f2 emulsion tubes, 180 Air-Corr.This is the latest update as suggested by Richard Parr. He has also mentioned that they have had success in shorting the length of the secondary venturies in the smaller disp. engines up to 2.2 .

Originally we were going to change the main venturies to 30mm as this was considered to be better suited to the small bore engines, along with the necessary changes to 125 mains etc.

The engine runs very good with the present set up but I think more improvement is possible & lean toward trying the smaller 30mm venturies.Let me know what has worked best for you. Im running the factory exhaust & have 150 PSI compression on each cylinder.

Thanks in advance

[Mr9146]

What was wrong with the Webbers?

[jhora]

Max...what distributor are you running with this engine...Thanks...John

[spyderwerks]

Nothing ....I have rebuilt them to the proper specs(125 mains, 30mm ven, f3 emulsion tubes , 55 idles, 180 airs) for 2.2 E .I set the floats static & then bench set the float levels with gas. These are low mi. (45k) so good shaft & butterfly specs. I will save them as they are original to the 914/6 ,a very low mi. documented 3 owner car. The only reason Im using the PMOs is they came with the car and I like the way they perform when set up perfectly. What is your experience with PMOs verses the webbers.When PMOs are adjusted to the max. potential they can't be beat. Im fishing a little to save perhaps a little time to get these PMOS perfect....there very close...but I want to explore a little more.

Max H

[spyderwerks]

John

Good question , I'm running a 2.2 E dist., it seemed to run fine with the original Marelli, but thought the 2.2 E dist.(006), might be a better choice, it seems to have made a slight improvement but nothing significant in my opinion. The 2.2 E dist. advances much quicker than the Marelli. The Bosch dist (006).is NOS.The Marelli is also in great cond.

I may go back & try the Marelli as I have made some improvements by using the f2 tubes vs the f11's with the PMO's.

The only difference in the engine verses the 2.2 E engine is the former owner retained the stock non-counter weighted crank & the original 2.0 heads.
The heads were machined to accept the 2.2 pistons. I realize that it would have been much better to replace the heads with the 2.2 Type, but the engine was rebuilt before I purchased the car. The compression as mentioned seems acceptable at 150 across the board, but valve size is smaller with the 2.0 heads as I recall.

Max H

[jaudette3]

What was wrong with the Webbers?

I'm not a carburetor expert but I've had the following experience. When I purchased my '67 it had Webers (2.0 engine built to 2.7). The car came from SoCal and we had to tune it for the elevation here in Central Oregon (4,000'). It ran great here but when I went back to sea level to run at PIR performance was lousy - had to shift at low 6's. We didn't re-jet or tune that day.

I decided to go with PMO's and, whew!, the performance is amazing. We provided them with engine specs, elevation, etc., and all we had to do was bolt them on and, with minor adjustments they ran great. Low idle (800 PRM), instant response, no dead spots, power to 7+.

Now here's the part that doesn't make sense...

Ran the car at Infineon and, without re-jetting or any changes, it ran great!

Anyway, I'm thrilled with PMO's - the best thing I've done to the car so far.

Cheers,
JohnA