cat n around

I run a 540 Merlin with a 871 Super Charger, with two 850 Demon Carbs., 10lbs of boost and am experiencing a huge amount of black soot on the transom. I was thinking of switching to a Champion Projected Fine Wire Spark Plug in hopes to reduce and/or eliminate the soot problem. Looking for any feed back from folks who may have had similar problem and/or running the same setup.

Turbojack

Problem is not your spark plugs but jetting in your carbs. In a blown motor the jetting is important not to get too lean, Get rich & transom gets black & you get to see black soot on water when starting motor. Jetting is a tricky subject. If you do a search you will find many threads on subject. I have procharged 540 & I spent 4 weekends & lost count of times tearing carbs down to rejet to get jetting right.

To start getting jetting right need to first find out what jets you have in carbs & what power valves you have. Are your carbs boost refrenced? Need to buy a bunch of spare spark plugs.

Earlier threads go into all the detail on how to check. Just remember "Black transom is better then Melted Pistons"

cat n around

Ihave 3.5 power valves,I have 87 jets on the primary,94 jets on the secondary.My pyrometer gauge is 1250 degrees on the primary wot is 1425 degrees. I thought a change in plugs might help.Ihave been using accels 141-plugs.