PMO Carburetors
10-16-2002, 05:43 PM
#1
2nd Gear
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Location: Chicago
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PMO Carburetors
I just installed a set of PMOs on my newly rebuilt 3.2L 911SC motor. The motor seems to run fine but I am running very rich and there seems to be a flat spot starting at around 3,500RPM till red line. It appears that right when the power/torque should be at its maximum 3,500-7,000RPM, it just flattens out instead.
Here are the specs on the motor:
*3.0 liter converted to 3.2 with new P&C. JE pistons.
*B&B exhaust
*964 S cams
Here are my questions:
1.Are there any good books to help me tune the PMO carbs myself??
2. Do I need to reprofile my stock distributor?
3. How can I fix the Flat Spot at the High R's??
4. Should I install the MSD CD ignition to upgrade the stock system.
Help!!
Geo.
Here are the specs on the motor:
*3.0 liter converted to 3.2 with new P&C. JE pistons.
*B&B exhaust
*964 S cams
Here are my questions:
1.Are there any good books to help me tune the PMO carbs myself??
2. Do I need to reprofile my stock distributor?
3. How can I fix the Flat Spot at the High R's??
4. Should I install the MSD CD ignition to upgrade the stock system.
Help!!
Geo.
10-16-2002, 08:52 PM
#2
RL Technical Advisor
HeyGeo:
You did not say what size PMO's you have nor anything about what exactly what jets you have, and those two things are key to sorting your problem out,....
Do you have sufficient and fuel pressure & volume?
Are the floats setup correctly?
Exactly how much ignition advance do you have at 4000 RPM? What plugs do you have in there and how old are they?
Answer all these things and I'd be pleased to help.
You did not say what size PMO's you have nor anything about what exactly what jets you have, and those two things are key to sorting your problem out,....
Do you have sufficient and fuel pressure & volume?
Are the floats setup correctly?
Exactly how much ignition advance do you have at 4000 RPM? What plugs do you have in there and how old are they?
Answer all these things and I'd be pleased to help.
10-16-2002, 08:59 PM
#3
Racer
Join Date: Jul 2001
Location: Torrance ,Ca
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It's probably your air correction jets. Usually a flat spot will occur from 4,000 rpm and up due to a lean condition, if you have the proper distributor advance.
Your main jets should be 160, idle probably 55 or 60, and air correction 175. It's best to spend some time on the dyno to get the optimum jetting.
Pick up a Weber Carburetor book, Performance and Pelican sell them. You'll need it. There are too many variables to say the settings above will be right for your engine. Venturi size, cams, ignition, altitude all play important roles in determining the right setup.
Good Luck !
Your main jets should be 160, idle probably 55 or 60, and air correction 175. It's best to spend some time on the dyno to get the optimum jetting.
Pick up a Weber Carburetor book, Performance and Pelican sell them. You'll need it. There are too many variables to say the settings above will be right for your engine. Venturi size, cams, ignition, altitude all play important roles in determining the right setup.
Good Luck !
