On last race, I run BRB P/S on JP FX-12 3port case and crankshaft. The top speed is very nice, not losing to new JPs.
The trouble is I losed 5 plugs during the heats. New plugs are put before heats, but it seems to lose it power after 2 minutes running and I'm losing the bottom-end power.
I'm using 0.5mm clearance below the underhead, with 25% O'donnel and Nova C7Tc plugs. Engine temp is around 115 deg C to 125 deg C. At last I use Nova C7Tf and it last for the 30mins final. But the plug's power seems to become weaker after 20mins run.
Any suggestions to solve this problem? Should I add another 0.1mm shim below the underhead?
Any help is appreciated. Thanks.