just bought a 3 door cosworth runs mint from cold engine is suppost to of only done 3-4000miles just noticed today driving with window down when i boot it and it comes on boost for a split second their is a rattle from the engine sounds like cam growl is this right or is it engine out for bottom end would a cam do this or would it ratle/growl all the time

 

under load the front cam bearings (ball races) can rattle/growl this can be cos the cam belt is too tight!!!!!

i used a bosch belt on mine which was really noisey the profile of belt looked like a pair of boobs

 

Where abouts in the rev range does the sound happen????

 

about 4500 rpm im thinking big end now

 

Usually low down and about 3500 rpm when your torque is highest

sure its not piston slap?

 

no not piston slap engine only done 3000miles sound like a growl big end striping it down anyway now new rods,arp big end bolts,al new shells,multlayer headgasket then back togeather