nikoa808 Posted May 20, 2015 Share Posted May 20, 2015 Hello, I'm having some massive popping sound coming from my exhaust during deceleration and consistant load at low speed. I was told my car is running too rich and I need to change my jettings on my carbs. I am pretty new to Mikuni tuning and I need some suggestions on jettings. I have a 3.1L stroker engine with 44mm triple Mikuni carbs. It is unknown of the compression ratio/bore size as the previous owner did not have any build sheet of the engine. I did verify the crank and it is LD28 crank when I pulled the oil pan off and checked the part number. It's got a F54 block with E88 head. The cam is made by America Cam (065) with Lift of 480 and 280 duration (verified by the company). MSD 6AL ignition system with Blaster 2 coil. 6-1 header with 2.25" mandrel bend pipe to Greddy exhaust. ignition is 10 degrees at idle. Currently my jettings are: Main air Jet - 200 Main Jet - 150 Pilot Jet - 55 Pump Nozzle - unknown Outer Venturi - unknown Fuel Pressure set to 3.5psi , no fuel return line I am in the process of installing Wideband O2 sensor to log the air/fuel ratio to further tune the carbs... Any suggestions is much appreciated to minimize the popping noise and to have the engine run smoother. Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 20, 2015 Share Posted May 20, 2015 What's a consistent load? Jetting by the numbers doesn't look that far off. What's the spark plugs show? Quote Link to comment Share on other sites More sharing options...
nikoa808 Posted May 20, 2015 Author Share Posted May 20, 2015 it pops when I'm driving at consistent speed of approx 40mph on highway... the plugs look to have a small amount of black carbon color... but not too bad actually.. Quote Link to comment Share on other sites More sharing options...
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