How To: (02Again M20 Throttle Body To M10 Intake Manifold)

[BadDays]

Hey Folks! If you stumbled upon this thread/guide because you're scratching your head and wondering how the M20's throttle body can successfully adapt to the M10's intake manifold? This is it, Here's what you'll need.

Parts / Tools Required:

02Again M20 Throttle Body Adapter Plate
Plate.
H5 Hex Screw Bit for the slotted head bolts that come with your adapter plate.
(1 285 330) M20 Throttle Body - This one doesn't have two ports at the base plus only one vacuum line!
M20 Throttle Body Coolant Gasket.
Two 10mm Wrenches.
E30 M10 Intake Manifold Gaskets.
Any M20 Intake Rubber Boot.
M20 Throttle Body Gasket Or RTV (Ultra Grey Or Black is fine)

Optional: Hammer

Got all of those? You can also take the time to adapt a M50 throttle position sensor or the 02Again Nissan 300zx Position Sensor, I did the 300zx sensor in preparation for Megasquirt but this also works for a completely stock engine as long you switch over the M10 TPS to the new throttle body! Alright Let's Begin.


Start off by having a clean work bench for this marriage of parts, We will assume you already managed to get the Intake manifold off the engine and you probably cursed at the last bolt at the bottom of the fourth port for 4 straight hours (The Bitch Bolt) Once you set your manifold on the table and you got everything you need? Begin by taking off the old gaskets and cleaning up the internal ports with some brake clean.
The original M10 gasket is no longer needed for this, You will either use the M20 Gasket that will mount to the new adapter or a good coating of RTV, Once you had decided your choice of gasket, Go ahead and figure out a way to get off the four studs that were originally mounted for the M10 Throttle Body. In this instance? I stacked two nuts against each other and proceeded to use the mentioned two 10mm wrenches to get the studs off one by one.
Once you take the time and patience to get the four studs off, You can now mount your adapter and then line up the holes so you can use the provided Hex bolts to screw down the adapter to the manifold, Remember that the 4 small holes are for your throttle body! Do not get them mixed up! The Hex bolts require a H5 screw bit or an allen key of similar size to have them screwed down in the large holes that you just removed the studs from.
For the second to last step for this marriage, You can reuse the original studs for the new throttle body but I will be buying new ones that properly fit the throttle body, Screw them down and then install the throttle body itself to the adapter (you might need to use more RTV if you find that there is a gap between the throttle body and the adapter) As for making sure everything is complete, If you bought a cheap random M20 Intake boot like me and you're fitting it to the throttle body, Now is the time to make sure that the throttle cable is facing the same direction of the original 318i throttle body along with the sensor as well! This is what it should look like:
i'm reusing the studs just for this photo but as you can see, (the ports that are for your coolant and PCV hose are meant to be facing on the back - UNTRUE) while the sensor is to the right, When you go to mount this back onto the engine, You might be able to reuse the throttle cable that came with your car but this is untested as of now.
(SEE PART TWO OF HOW THE THROTTLE BODY IS MOUNTED)

Well then! I hope this helps you in your journey of squeezing as much power you can out of your M10, Thank you to 02Again for helping the M10 community as long with the E30 Community, Cheers!

[BadDays]

UPDATE:

This is how it's fitted into the car once you manage to get everything hooked up! Let's go over the rest of the installation.


Part Two of adapting the throttle body requires you to figure how the coolant hoses and ICV hose will hook up in this scenario along with the minor things needed for this setup, However if you want to keep the L Jetronic system on your car and you want to do this modification? I can't say for sure that it'll work!

First, We must address the throttle cable itself!

I already solved the question with a thread in the M10 section but it's more helpful if I just repeated it here:

For the throttle cable itself? You can adapt your original M10 throttle cable to the M20 Throttle Body by using the second cable bracket on the throttle body itself, Don't try to use the first cable bracket on the top because you won't have enough movement for the butterfly to open properly, You will need to use a different retaining clip so it's a good idea to buy one for a M20 ( Clip: 13541747519 ) Once you install the clip onto the cable and then you can shove it onto the second bracket, Adjust your cable for some play since if you have a cable that is too tight, It'll snap at some point! The Adjustment for the cable is a 17mm and you can adjust it however you deem fit, Just ensure that it's still tight enough for proper movement.

As for the Coolant Hoses!

The Throttle body must be mounted facing the shock tower instead of the engine block for proper throttle cable movement and the sensor on the right, However the hoses must be custom made from fuel hoses or heater hoses since the factory hoses will be too short for this application, This also applies for your idle control port! The left coolant port is for the water pump and will be mounted as such, Follow the realoem diagrams of the M10 Cooling Section, Meanwhile the right coolant port is for your engine block and there will be a port itself to fit the hose to your coolant port on the throttle body, Finally there is a port meant for the Charcoal Canister and in the provided picture, The throttle body that is mentioned in the first part will be used as such, The one brass port on the top is fitted with a hose to the canister. That's a lot of ports! You should install the intake boot first and then mount the hoses due to the tight nature of everything in the engine bay, Don't worry if you can't adapt the AFM because this upgrade does require a custom intake tube to the airbox in the first place.

Part Three will include the installation of the Idle Control Valve Upgrade and that includes the ICV port.