Originally Posted by
Ahmotorsport
Is it proper fuel line? If the pipe is not designed for fuel it will deteriorate and kink up causing a restriction in the fuel line. 6250RPM is peak for a Cosworth, it may be true that the cams don't peak out till 6400 but boost does at 6250. If it sounds sweet up till 4500RPM it isn't cam or ignition timing. Did it do this before the chip was fitted?
chip was all ready done had car for 8yrs cant remember what it should go like havent driven it prop 18 months used proper fuel line when i floor in neutral what should rev to thanks