i thought your thread a while back was about the cs-440, not the 400?
i recall mentioning that the 520 engine assembly would drop on the frame with little or no mods.... that was before the 'echo police' here jumped in and told me i was wrong (i wasn't ).
on topic:
OP, you need to go to the echo website and sift through the IPLs like i did and start comparing part numbers with saws close to the 400 in the lineup. find one whos frame and oiler, especially, will interchange and then look at the other peripheral parts.
08f150:
i am not real familiar with the 400 but i can tell you the 440 and 520 are clamshells too... but in a non conventional way. the clamshell is three pieces. the cylinder on the 440 and 520 is removeable from both the lower clamshell and from an upper clamshell that carries the bearings. the cylinder can easily be turned down and the piston turned for a pop-up.
if the 400 follows suit then.............................................
Volks, the Echo police are back, I was wrong about the 440 and 520 engine not fitting in the same saw, they do but are 2 different engines with to 440 being the only one I've found with the 3 piece clamshell and the 520 being a 2 piece clamshell. I've found with a muff modd the CS440 is just so so, the CS520 is a little high RPM hot rod that has torque also, the CS400 while not being as high RPM as the 520 cuts fast with the NK chain and huge torque for 40 cc's Steve