On a recent trip I made a forced landing due to fuel entering entering around the firewall. This may have happened many times previously but I haven't noticed the fuel before .

At height above 5000 ft (wot 5100-5200, 24-25 manifold pressure) there has always been a fuel smell. Investigation have always found nothing other than fuel staining at the bottom of the air cleaners.

This time however on landing there was still fuel dripping fron the LH cleaner, the right was damp. We ground ran at wot and couldn't reproduce the leak( @1100 ft) the rest of the trip 8 hrs was at >3000 ft with no problems.

any ideas?
Fuel pressure at cruise is 4.8 psi the engine is smooth,EGT's run1500-1400 depending on height and temp,the floats (150 hrs from new are all 3 gr each)
my float levels are set 1/8 lower than std due to rough running at taxi over rough ground and hot start flooding.

i have a theory but would appreciate any other suggestions.
cheers
Dusty