Calling all Carb GURUS.....

[Nape75'911T]

I have had my car for a little over a month. It is a 75 tub, with a 74, 2.7 motor, converted to Webers.

Just got it out of a very highly recommended PCA endorsed shop yesterday, where they really cleaned up a lot of small items for me.

The car runs really rich, almost Hemi rich! The plan is, to send the jet information to PMO, and see what they suggest for jets, as the mechanic feels the jets are incorrect.

The compression test was good, 155 - 165 psi across the board. Leakdown was excellent, no issues there.

Here's the catch. We are sure that the cam has been changed, but have no idea what is in there.....

Here are the jet numbers.
Idle Jets - 55
Main Jets - 135
Emulsion Tubes - F3
Air correction jets - 150
Choke - 30

Those are the numbers he pulled from the carbs......it's all Greek to me.......

Your thoughts are appreciated.

[Nape75'911T]

bump

[jpnovak]

If you check the archives you will find some 2.7 jetting specs for webers. Here are the Steve Weiner 2.7RS specs:

60 idles
F3 emulsion tubes
155 main jets
180 air corrector jets

The venturi and emulsion tube sizes will depend on what cams. I would think that you could use a F26 if you have mild cams and a 32 or 34mm venturi depending on where the rpm band is.

Are you sure its not running really rich due to tuning and carb adjustment? Is it rich at idle, low rpm, high rpm or WOT? Do you have any AFR data? btw, webers will usually run rich to avoid a flat transition from idle to high speed circuit. Just keep the rpms up to avoid fouling plugs. After the car is warmed up frequent trips to the redline will help keep them clean.

[randywebb]

either swap the jets over & over again
OR
figure out what cam is in there

[Nape75'911T]

since the last time I checked the board, tech called me back to say that PMO is suggesting leaving the idle, E tubes and mains alone, and adjusting the air corrector jets, and the venturis.....btw car is rich at low speeds. Also seems to be an issue with float level on one carb, and he is going to tinker with mixture settings when car goes back next week for the new hardware.

Car starts and runs really well though, and from 3K to redline, screams.......I love it. The sound is awesome, perfomance is great, and with all the suspension upgrades that the PO did, handles really well.

Grin factor is a 9.....at least it was until the tech took me for a ride in a 500hp turbo that he just finished tweaking. Then again, that car transcends grin factor, straight through to pucker factor!!!!

Thanks for the suggestions, I will let you know what happens.

[john walker's workshop]

try 150 mains and 170-180 air. a smaller air jet like yours allows the main jet to pull a lot more fuel at higher rpms. if you're rich smelling at idle/low rpm, perhaps it's not adjusted correctly. also, don't trust any jet numbers until you have checked them with a jet gauge. anyone could have run a drill through them.