It has long been the norm to use subframe spacers while preforming the m60 / m62 v8 swap into an e30. Where did this norm start? Well basically as far as I can tell it started with an old-er swap guide which you will find somewhat translated here. So for the sake of convenience people started following that guide, and because 300mm (a website) was offering the motor mounts and spacers (if you use said motor mounts you have to use spacers), not knowing otherwise people bought said products. Now generally speaking as far as quality im sure 300mm produces a nice product, however I just do not agree with the execution.
You see, without the subframe spacers the engine sits on an angle, this angle puts pressure on the guibo and the rest of the drivetrain, and generally reduces the amount of space above the engine for things like strut bar. To eliminate this angle the practice has been to use subframe spacers as such:
The reason why subframe spacers are bad is because it raises the body of the car in relation to the subframe, you alter the cars centre of gravity, suspension dynamics and create bump steer.
So what do you do? Well first and foremost you will not be able to use the 300mm mounts, you will have to make some yourself. You have to make the motor mounts yourself because a. no one is currently offering mounts for the configuration I am about to propose b. the 300mm mounts will not work because you will be lowering the engine in relation to the subframe, and considering the mounts connect the engine to the subframe it is only logical that need mounts that will be shorter in height.
The solution is to notch the oil pan, so you can lower the engine more without it hitting the steering rack. There are some select few people who have done this with success. Here is what a normal oil pan looks like (you will only be modifying the upper oil pan):
You will notice there is a buldge in the middle of the pan just right of the mounting bolts for the lower pan.
Here is what, where, and how you will modify it:
Using this method will eliminate the need for subframe spacers (no bumpsteer, suspension geometry stays correct, center of gravity is not lifted), and will reduce the drive train angle to exactly where it needs to be for long term reliability. Considering your saving money on the subframe spacers and on buying motor mounts this method shouldn’t cost you anymore then the former method. I recommend contacting a competent welding shop to notch the oil pan, these shops are usually plentiful in most towns.
When I cover all aspect of the swap myself I will compile and upload a better more ‘improved’ guide on how to do the swap.