PMO/Weber jetting advise needed
 

Hi Guys,

I have a new engine build and could use some help on jetting to get me in the ball park. Unfortunately Richard Parr sold PMO to Empi and they are no help. Once I'm in the ball park I can take it from there with my LM-2 and my seat of the pants dyno.

The engine came to me as a 3.0L with PMO 46's and I rebuilt it to 3.5L Using a new set of Mahle Max Moritz style pistons and cylinders and a 964 crank. Original plan was to build a 3.2L with Mod S cam but that changed mid build to the current configuration which will have less peak HP but a lot more low end torque.

3.5L Specs:

SC cam (stock)
Intake 38mm
Exhaust 35mm
35mm headers
PMO 46mm

Current PMO setup:
Venturi 36mm
Idle Jet 55
Main Jet 135
Emulsion tube F7
Air correct. 175

Using Paul Abbotts (Performance Orientated) formulas and his Venturi selection chart I came up with the Venturi selection of 42mm. Now I need a general starting point for the jetting.
New Setup:
Venturi 42mm
Idle Jet ?
Main Jet ?
Emulsion tube F7
Air correct. ?

Anybody got any ideas what would be a good starting point for my jets and air correction?

Thanks in advance,

On my 2.8 with 46 PMOs
Venturis- 38
Mains- 160
Main airs- 175
Idle- 60
Idle air-110
Emulsion tubes-F16
My heads are Ported
40 intake/ 35 exh.
Running RSR headers with 997 GT3 Muffler
Mod S cams
Hope this helps. Richard helped me out to get it dialed in.

Thanks for the data points.

Everybody likes pics so here's a couple.

http://forums.pelicanparts.com/uploa...1688084956.jpg
http://forums.pelicanparts.com/uploa...1688084956.jpg

3.2 with a very aggressive cam, dyno'd 274 whp
46MM PMO
Vents - 38 was 40
Mains - 175
Idles - 60
Tubes - F16
Idle Air - 130
Air Corrector - 180

Thanks for the additional info. I ended up talking to Richard Paar yesterday. Turns out a friend of mine has been working for him lately. I'll post his suggestions here incase anyone else has a similar engine build. I'll post back as well once I get a graph of the AFR's from my LM-2.
His suggested starting point.

Idle jet 55
Main jet 155
Air correction 185 (not available so 190)
Idle air 130
Venturis 38mm

Any progress?

Any progress?

Ian