[Curt C.]

Go to the book store and get one of the books on how to tune Holleys or BG's. I believe Cartech makes them both.

You have multiple circuits here that need to be addressed. Hook up a vacuum guage to the carb and set the idle screws with it. You are looking to achieve the highest vacuum while maintaining the desired idle RPM. Make sure the throttle blades are set accordingl to BG specification. Also, you have to set the timing accroding to BG - initial at 16 - 18. Make sure total is where the engine manufacturer suggests. This will help a lot. It should not diesel after doing these items but if it does you can pull a degree or 2 out of the initial or slightly richen the idel circuit.

With the idle mixture set then start looking at the jets by reading the plugs. Better yet, go out and get a wideband 02 sensor from the likes of PLX or Innovate ($350). Install a bung in the exhaust, plug in the 02 and carb tuning becomes much easier. Or, put it on the Dyno and use their wideband.

By the way, I would think an 850 would not be too much carb either.