Specific question for those that have a 6, with a 123 unit and webers Options

[Cfletch]

Sorry, pretty specific question for those with a 911 engine, 123 ignition, and weber carbs.

I have 3 the above, and was curious about the using the MAP curve. I have the PMO manifolds and I believe that has a plugged port on each side for vacuum, and I'm not sure if that's the correct port to use to get a vac signal to the distributor.

Additionally, what is the real benefit to this. From what I have seen on Pelican Forums is that it may help with getting MPG/efficiency improved. How does it do that? Working on getting my carbs more dialed in and working on some mid throttle lean symptoms, but also wanting to play around with this port when the time comes.

Just loaded Ben's curve he has posted a few times in the pelican forum and have yet to try it. Noticing lean pops from carbs at ~3k rpm on Freeway and holding around that RPM. When accelerating I get no pops and smooth accel. It just pops when essentially maintaining 70ish MPH in 5th.

[930cabman]

Sorry, pretty specific question for those with a 911 engine, 123 ignition, and weber carbs.

I have 3 the above, and was curious about the using the MAP curve. I have the PMO manifolds and I believe that has a plugged port on each side for vacuum, and I'm not sure if that's the correct port to use to get a vac signal to the distributor.

Additionally, what is the real benefit to this. From what I have seen on Pelican Forums is that it may help with getting MPG/efficiency improved. How does it do that? Working on getting my carbs more dialed in and working on some mid throttle lean symptoms, but also wanting to play around with this port when the time comes.

Just loaded Ben's curve he has posted a few times in the pelican forum and have yet to try it. Noticing lean pops from carbs at ~3k rpm on Freeway and holding around that RPM. When accelerating I get no pops and smooth accel. It just pops when essentially maintaining 70ish MPH in 5th.

I have 2 out of 3, a 2.7 911 engine with Weber 40IDTP carbs. Also experiencing some popping. Currently I am looking into going with 60 idle jets and/or cleaning the idle passages, also retarding the spark a few degrees.

[gereed75]

I assume when you say popping you are referring to the random intermittent sort of staccato little “chuffing” induction noise that sounds like a sharp whispered spit. Most call it spitting??

Mine does it. 2.4, carbs, stock distributor, Parts Klassic CD ignition, mod solex cams, 9.5:1, S ports and valves. At idle and at steady throttle cruise. No discernible effect on power output.

Car runs great. Idles at 900 - 1000 rpm. Pulls hard and cleanly from pretty much any RPM. O2 sensor shows AFR’s at 12.5-13.5 pretty much all the time. Maybe 14.5 at idle and cruise. Carbs are in good condition with proper fuel levels. Timed at 30 degrees BTDC.

Some more particular than me might call it a problem. I think it is more the nature of the beast - high compression, cam overlap, slow turbulent flow in big ports really close to a big inlet valve, throttle plate barely cracked open, crappy gas.

If you find a solution, let us know. Good luck. In the meantime time I’ll be driving.