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Just a quick run down what is required to fit a m20b25 to a e21 323i

I have the full 325i running gear, engine,box,loom.ecu etc

The 323i is complete and is a manual

So what mods are needed to the wiring will the standard 323i engine mounts work?

Also will the manifold need any modding? currently have a 6 branch on the 325i engine

Any info would be appreciated

Will do a gallery very soon of the e21 in progress

ohhhh someone else b25ing an e21!
battery needs to go in the boot and run suitable live cable to the front and cut the e21 battery tray out.
wiring wise theres 6 wires to solder from the c101 plug on the e30 engine loom to the e21 engine loom plug on the e21 fuse box.
you need to mount the coil on the o/s inner wing and lengthen the wires on the e30 loom to it.
you need to cut a hole in the baulhead somewhere on the passengers side, to pass the loom thru to mount the ecu above the glovebox.
theres other stuff too but, littler things really.

you dont need or want the e30 gearbox as theres no cable speedo drive in it.
engine mounts... you need the ally "legs" off the e21 engine bolting on the 325i engine. thats it.

id also swap sumps to the e21 tin sump while you were at it mainly cus you dont need it and (if your cars lowered...) it dints when hit on the road insted of cracking and leaking..... and you can sell the e30 ally one for £20-30 on ebay! like i did. (cashback!)

murran wrote:ohhhh someone else b25ing an e21!
battery needs to go in the boot and run suitable live cable to the front and cut the e21 battery tray out.
wiring wise theres 6 wires to solder from the c101 plug on the e30 engine loom to the e21 engine loom plug on the e21 fuse box.
you need to mount the coil on the o/s inner wing and lengthen the wires on the e30 loom to it.
you need to cut a hole in the baulhead somewhere on the passengers side, to pass the loom thru to mount the ecu above the glovebox.
theres other stuff too but, littler things really.

you dont need or want the e30 gearbox as theres no cable speedo drive in it.
engine mounts... you need the ally "legs" off the e21 engine bolting on the 325i engine. thats it.

id also swap sumps to the e21 tin sump while you were at it mainly cus you dont need it and (if your cars lowered...) it dints when hit on the road insted of cracking and leaking..... and you can sell the e30 ally one for £20-30 on ebay! like i did. (cashback!)

Thanks for that so it is what i expected Just wanted it all confirmed and you have added a few thing to the to do list

Regarding the battery cable will be using a e30 boot kit so that should not be a problem. Will need to think somehthing up for the battery clamp in the boot area (if i cant use the e30 kit)

Sounds easy

The E30 kit is slightly short. I would use an e36 battery cable

the e36 cable is really thick stuff and doesnt bend. i saw the one drgonzo had to do his.... was a bit overkill. he chopped up some good quality jump leads and bought some new fittings in the end (like i did.)

Yeah that big E30 cable just didnt bend into the nooks and crannies of the E21. Use jump leads like Murran says or buy some heavy gauge wire. I got 6 Meters off Ebays for a fiver, bargain! Regarding the tray, just chop the E21 one out and bolt it into the floor of the boot. Simples

Thanks for the info guys

Would the manifold catch the rack though I currently have a 6 branch fitted.

Exhaust should fit as is now. Its the same engine dimension wise

DrGonzoPOW wrote:Exhaust should fit as is now. Its the same engine dimension wise

Sorry to clarify I want to keep my 6 branch on rather than the 323i manifold

youd most likely have trouble fitting it tbh. catching the steering rack input or the chassis leg. nothing you couldnt sort out tho, would just need a slight re-working at an exhaust place.... then something making up to connect it to the 323i system.