Identifying motor parts
 

OK. So a friend of mine had a 318is e36 with a built or rebuild motor. I want to say it was an early 90's car, maybe 1992. He had a wreck in the car where the car went up over a curb and damaged the front subframe, oil pan, etc.. and the car was totalled out.

The car was pulled apart and various parts sold by him and the member Viper on here. The motor was pulled apart and has been sitting in Vipers house for the last three years. Viper gave the motor to me, so now I'm trying to figure out what this thing has in it, and what is valuable and what is just stock. Even just stock is ok with me, as it is always good to have a spare motor for a dedicated track car.

The motor was rebuilt by a race shop up in Ohio at some point to the tune of $8,200 dollars. Looking at the motor, I can't tell anything that has obviously been changed such as boring of the cylinders, flowing of the head or any radical changes. The pistons look stock, as do the camshafts. I've not pulled the bottom end apart to look at the crank. The prior owners believe the car may have had increased compression, but the receipt just lists a total price for the motor.

So, to my question, how do I figure out what is stock in this motor and what has been upgraded? Also, what is different about the 92-93 M42 from a 95 m42 in terms of the block and the head? If I had this motor put back together, could I easily just swap motors and have all of my electronics work?

Outlook not looking to good on this motor being any good at all beyond maybe some parts, or cores.

I cleaned up the bottom of the pistons, and two of the pistons have valve impact damage. One of the camshafts also has some scoring like something got between it and the journal, or the motor was run dry.

At least the block and the head looks healthy, but definitely needs some work. Not even sure if it is worth it to have a machine shop look it over for any less obvious signs of damage.