i just bought a used jdm engine and there’s a lot of carbon build up in the intake manifold the exhaust ports.. the intake ports had a little and the spark plugs have some and the top of the pistons look dark as well..

is is this something i should be concerned with? the engine is all stock but do you think it’s running rich or something??

 

it's probably normal. Could have a decent amount of miles on it. I've had engines look almost brand new and some not so much. Luck of the draw.

 

yea they said it had about 50k but who knows.. looks like it was running rich but i’m goin got do a leak down test

 

i’m doing a leak down test and some of the cylinders are reading high.. now the motor is cold and has some carbon deposits so idk how accurate it is.. i wish i knew for sure

 

where did you get the motor from ?

 

Perfectly normal, I would be worried if i didn't see any, because that usually means that the engine was cleaned up for hiding something worst (happened to me), just beware of oil!

 

I agree with Chris, especially if one of the piston crowns is squeaky clean. Classic head gasket issue