I have a Isuzu engine installed in my 1972 Jeep cj3b . I dont know what model is the engine from but i heard they were used in isuzu vans. Its 2.4 litre engine without turbo. It throws black smoke when revved hard while driving on the highway beyond 60km/h. Before 60 km/h the pickup of vehicle is good but after that it emmits accessive black smoke and does not respond progressively in terms of pickup. I saw oil leaking out of the engine when i opened the bonnet. I got the engine oil tank gasket and repaired but the oil seems to be leaking round the engine. The engine has lot of vibration and noise as well but i dont mind it if its running well. It takes a lot of time and black smoke while i start it first time in the day. Its winters here. I live in India.