Hello guys,
 
I have a problem. my xflow has twin 45 dcoe. i did a track day on the weekend. its the first time ive been able to run the engine in anger.  i found that at approx 5500rpm the engine had a misfire.  
one of the carbys had alot of black "soot" around it and when i got home i pulled the carbs/intake off and found the following. 
 

 
had melted the plastic "soft mount spacers"  however the o rings appeared to be intact 

 
back of the carby 

 
 
 
Im not sure if this was causing the misfire, or a result of the misfire.    ive run thru timing, valve clearences, spark plugs. all appear good. also worth noting the webers were purchased new and tuned on the engine
 
as this is only happening on 1 carby could if be due to having the carby too loose on the soft mount?
 
any other suggestions?
 
cheers
 
 

Is the mating face between intake manifold and head perfectly true and or gasket good? The area that the soot is placed makes it look like it has come from the direction of the head? or rocker cover? But i could be completely wrong though, just looked to me like thats where it came from and to me the carbs look like they have sealed properly as the soot doesnt go past where the soft mounts were
 
Great job with that 1.30 by the way man thats a wicked time!
 
Ryan

45's on a kent would be considered massive and may contribute to the poor running??!!  What size chokes you got in there? If the rubber has melted then the carby(ies) must be backfiring.  Once the rubber went the backfires then came out between the mounting surface.
 
....uneducated guess....

 In high states of tune 45's on a crossflow is quite acceptable! espically turing high RPM and seems to be the norm in racing circles and definatley used quite widely in the UK, ive even seen 48s being used on stroked out and overbored xflows...Bet they sound the NUTS wen there on song! YEW!