Leaner Jets or Hotter Plugs ?

[37fatfender]

My situations is a 40 Coupe which I bought. The engine runs well but rich based on my spark plugs. Genarlly black all the time. I am pretty sure its a 239 but I have never had the heads off. The setup is running with two 97's jets with 43's and 65 power valves on a PM-7. The ignition is stock (12 volt). I consume about a quart of oil every 500 miles, althought it does not smoke. I have Autolite 216 plugs (.025 gap) in it now had NGK B6L before, both looked the same after driving. Both carbs were recently rebuilt and the floats adjusted. Also running a stock fuel pump. I am debating going to 41 jets or should I run hotter plugs? I am thinking if I am using oil a hotter plug would be more apropriate. So what direction would you go?

 

[ken ct]

Personally if you have the parts i would try .042 jets and #69 PV's and take plug readings if still rich i would go hotter on plugs.OMO ken ct.

 

[V8 Bob]

As Ken stated, try going to a hotter plug, like NGK B4L, that resulted in cleaner plugs on my multi-carbed flathead. Also make sure your floats are adjusted properly, and that the fuel pressure is 1 1/2-2 psi.