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I am building a triple carb M20, (I wont change my mind half way through!)

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Battery install complete for now, The car runs on the one PC680 just fine, amazing such a small battery will happily turn over a six like this but there you go. I installed with an isolation switch through the kick panel:



With that done a I spent a week tuning the carbs as best as I could given the jets I had. I also had to tackle multiple oil leaks and coolant leaks from all the adhoc pipework. It will probably never be 100% leak free particularly with coolant as there are multiple joins in all the non-factory pipes.

With that done I now just needed to get an exhaust and the centre bearing mount fabbed up. Not something I am able or willing to do myself. The car cant really move without these so it was on a trailer to the workshop. Lathom Motorcraft specialise in bespoke exhaust systems and came recommended they did a great job I have to say. They even got it to go over the rear beam. The system is 2.5" full stainless. They also did the centre bearing mount for me.







My only issue now is ground clearance, the much bigger diameter pipe and bracketry gives me very little clearance now maybe 4-5 inches at best.

Now my car was almost ready for an MOT I needed to replace a strut bearing as my N/S one has totally given up after only 2 years since new, strangely my O/S one looks perfect even though they were done at the same time...??


Finally off to the MOT station...it passed!


So now I have MOT tax and insurance and a car which drives! It does however still require proper rolling road tuning and jetting, the carbs are definitely not fuelling correctly and it bogs down some on idle circuit to main circuit transition. I will hopefully be getting a session in the next 2 weeks or so. After having my previous M10 carbs rolling roaded I know how much of a difference it can make. Even so the limited driving I did to the MOT station and back it pulled like a train, the torque is immense compared to the M10 I have to say. I think I could destroy most things on an A road now! The stopping power of the brakes is massive too, maybe even too big in the wet i will have to see. Also it obviously sounds amazing and drinks fuel. I will attempt a video once it has been rolling roaded. Still some jobs to do though:

Wheel balancing all round

Rolling Road

Alternator regulator upgrade to get my LED lights to work again (14.5V required)

Tacho mod to get it reading correctly

Still no ARBs as the front one wont fit (bilstien sports all round make for little roll anyway mind)

So I got the the rolling road on Friday.

R.E. Performance is the only place in the NW I can find that can tune carbs. They are properly cool and old school. Ken must be nearly retired now but must have decades of experience in carb tuning, he knows his stuff. They also have full sets of jets for nearly all carbs in stock so there is no faffing around trying to get the right ones. There is something hugely reassuring about turning up at a place like this where there is just one old guy pottering around, racks and racks of jets and carb equipment and a rolling road that must date from the 80s. It fills you with confidence that they have seen everything and know everything. Everyone else just wants to plug in a laptop and be done with it. Multi carbs take skill and most importantly experience.






All the jets for all the carbs!



Even the receipts are old school:


So as the result shows, after some rejetting I achieved 182bhp at the wheels which is in the region of 220bhp at the flywheel, was hoping for anything more than 200 so I am pretty happy with that. From what I hear it is not easy to get more than this kind of hp out of the M20 when naturally aspirated, probably only with ITBs and even then only slightly more. The engine certainly isn't hindered by the fixed ECU ignition setup, I don't think there would be any benefit from going to mechanical distributor, and a programmable ECU would probably give very marginal gains. Overall I am very happy with the performance of the carb setup, it pulls very hard right through to 6000rpm, the car takes off in 3rd gear like a rocket and sounds amazing. For any future reference the jetting is:

Main Air - 225

Main Fuel - 165

Idles - 50

Chokes - 36 (Might possibly need to go smaller)

Now i just need to refresh the oil after the engine build and I need to get saving up to keep fuel in the tank. No real idea on economy yet... :S

A big thanks to AndySals for keeping me company during my 3hr wait!


She's Alive!

Weekend Update ;)

So firstly heres what my loom was like just before I dug into it, filthy, horrible and suspiciously buried in electrical tape:


I removed all the tape and wrap from all the engine bay wiring and I cleaned all the cabling up. Above mentioned terrible connections by PO's were found:


These were all properly soldered together and heat shrinked, I don't have a specific picture but you will see repairs in later pictures.

Moving on...

M20 Loom going in:


It has to run between the servos and the engine as the M20 loom was mounted against the engine so the cables are all short. No way to mount this on the wing...


I mounted the C101 plug and the loom relays on the wing. The C101 plug is the main M20 loom plug, the top half of the plug goes to the M20 loom, ECU etc the bottom half is what needs splicing into the '02 loom.


Splicing in the plug to the 02 loom. This sounds bad, cutting up '02 looms, but it only takes 7 wires to splice in, and if you are clever you don't need to cut some of them, I only ended up cutting 4 wires I think. all cuts and joints will be hidden once the loom gets wrapped back up. My aim is to make the loom appear original and untouched without lose wires everywhere. I just have to get everything running properly before I can do that.


I have bundled up all the plugs to sensors and equipment I wont be using due to the carb setup - Throttle Sensor, Air Flow Sensor, Injector leads etc. I will put these in a little black plastic bag to keep them waterproofed and semi hidden. If I ever want to go injection I can just bolt on the relevant parts and plug in.


Distributor fitted with leads:


Passenger footwell minus glovebox, all this cabling needs fixing down and tidying up:


Had a bit of trouble trying to get my engine to send a spark and get the fuel pump to run. With having so much equipment unplugged and no one to ask who has done this setup before (M20 with ECU ignition) I had no idea if it needed signals from missing equipment. Eventually I found out that it was the fuel pump relay. As the original high pressure injection fuel pump pulls lots of amps it is on a relay with a signal to the ECU, however my low amp carb fuel pump does not pull enough amps to switch the relay when signalled to. As it is such a small (5 Amps) load the fuel pump on my setup doesnt really need to be relayed, so I did this little bodge so that the pump runs when the "relay" is signalled.


Making the spacer I need for my water neck out of some sheet 10mm ally, took some time with primitive tools;





So now my engine turns over on the starter, the fuel pump works when it should and its getting a spark when it should. I still need to:

Route all my coolant pipes and fill with coolant

Install electric fan wiring

test compression

final fitment of carbs and manifold

accel cable linkage setup

carb setup and tuning ready for the main event, hopefully next weekend


Weekend update!

Final installation of manifold and carbs, I hooked up the accelerator linkage and the rocker breather hose


Performed compression test, all cylinders were 170-180psi


Final installation of the water neck with the spacer, and custom coolant pipework.


Fitted HT leads and conduit, exhaust downpipe, filled with coolant...


When filling I noticed the heater valve was leaking, as the M20 runs a pressurised system this would be no good, I found the O-Rings on the heater valve had gone totally solid, I replaced them and all appears OK


Added some engine break-in fluid...


Switched on the ignition to fill the carbs with fuel, seconds away from starting up I noticed the front carb was flooding petrol into the cylinders :( Cylinder 1 had a lake in the manifold....


I found the pump circuit diaphragm had perished and was passing fuel. I had checked everything except the pump diaprams on the carbs... typical really. The other two carbs have had their diaphragms replaced at some point but this one is an original one. This has put an end to my hopes this weekend until I can get a replacement :(


I moved on to other jobs...

Fixing down ECU and cabling in the passenger footwell, I could have put it in the glovebox itself but it would have been much more work, I will have to make passengers fully aware of their responsibilities, I dont think there will be an issue in all honesty



All dissapeared!


Starting on my under seat battery setup, I'm doing the double Odyssey PC680 setup, you should get away with one on an M10 but the M20 will require that much more cranking.



I used sticky back closed cell foam to mount the battery on.



Still to do:

Start the engine!

Fit 2nd battery and hook up in parallel

install rear brakes

bleed the whole brake system

obtain front ARB and fit

get exhaust system made


Belated weekend update!

Firstly she's alive!

Started her up on friday, a couple of pumps and she fired into life almost straight away. Once warm she held a poor idle before I managed to balance the carbs with a synchroniser and leaned off the idle mixture. I ran her upto temperature for about 30 mins with lots of revving. At the moment the car has only a downpipe and no exhaust, also the downpipe is rattling on the floor of the car and steering arm so she is very loud and has knocks which makes it hard to tell just how well she is running but I think its actually quite good. Doesnt sound like she bogs down on acceleration and she returns to idle smoothly and quickly. She also maintains a consistent revs at idle. The bigger cam etc means the idle will never be super smooth which makes judging things harder again. Once I get a proper exhaust made I will be able to tune the engine better and get an idea of how good or bad she is running. Before rolling road. Couple of things I do need to sort, 1) the rev counter is 50% out as I expected, (i believe there is a fix for this) and 2) there is a big oil leak from the top of the cylinder head to crank case oil return pipe, I hope this is fixable without having to pull all the carbs and the manifold. which the pipe plumbs into.

So with the engine running and all the electrics testing out OK I got to the job of wrapping the loom up.

Here is the bulk of my task:



All wrapped:



Even got new piping for the washer system and hooked that up:


With the engine now running and the wiring finished, I now need brakes and propshaft for a car that moves and stops by itself!

I used a wooden pole to cut to length and wedge between diff and gearbox output shaft to ensure a straight and accurate measure of the cut down prop, you can see it needs about 3 inches removing:


I also decided it would be easier to mount the centre bearings on the current mounts than make and fit new ones, you might be able to see (if you click on the image) that on the pole I have marked where the mounts are for the centre bearing and therefore where it needs to lie in the length of the propshaft:


All this means that the prop needs about 6 inches taken out the front part to correctly locate the centre bearing and then 3 inches lengthening the rear section to make it up to the correct length. I took the prop to North West Propshaft services (very good people) for modification and balancing.

My brakes are on the case for next weekend and installing the propshaft. I hope to then have a car that can move and stop. Then its off to the exhaust shop/MOT shop.


BH weekend update...

Got the prop back from the shop, they did a good job:


My mistake was to not ask them to loosen the centre adjusting nut. The E30 prop can be adjusted in length by about 20mm and I must have measured slightly out as the prop was about 3mm short. The centre nut was a TOTAL BASTARD to undo, as you can see you pretty much have to destroy it to get it off. Even with the biggest set of stillies in the world, I very nearly gave up. Its a terrible design really, the 46mm "nut" if thats what you call it, is torqued to death yet at the same time the turning flange is really narrow gauge, it should be 1/4 thick at a minimum maybe thicker, as it is, to undo it you have to totally mangle it...


Anyway once loose, I fitted the prop. I had read that the E30 prop should bolt right into the 02 well it doesn't in my case, I think this is partly due to the medium case diff I have installed as it sits about an inch lower than the std small case. Even so I don't think it would have bolted straight in...? You can see I had to cut a chunk out of the stock mounts to give clearance to the centre bearing. I will need to fabricate some mounts for the new centre bearing.



I like subtle bling and a especially a nice weighty shifter knob, other than this and the period recaros I will keep the interior stock (unless I can get a period Petri wheel)


I have longed for a set of rear wilwoods to match my fronts for a while, well after getting my bonus from work I paid the exorbitant cost for them from IE plus shipping plus tax... ouch. Well once arrived i found that just like my fronts the 15" kit doesnt fit under my 15" wheels :evil: so they then cost me more money to get the discs and the mounting brackets turned down to get them to fit under the wheel, after LOTS of trial and error they eventually fitted.



I bled the brakes and clutch:


Brakes still a bit spongy, I will bleed them again I think, having said that I find the willwoods result in a spongy pedal when I fitted the fronts as the alloy caliper body flexes noticably when you press the pedal unlike the cast iron ATE ones.

I ran up the engine again, rebalanced the carbs again (I'll be getting used to that), I semi fixed the oil leak from the top of the return pipe to the block, it is no longer a flood, but it is still leaking, I dont know what more I can do other than fit a new o-ring and filling it with sealant gunge as well. I torqued the head bolts at running temperature. I refitted the bonnet, the spring bar which runs across the underside clears the front cooling pipe, just about, after some fettling. The carbs have about 2" clearance from the bonnet the rear once are not an issue. I fitted the front grilles, tested all my lights and horn. And added the final touch... a full set of new stickers!

So although she isn't actually on the road yet as I still need a front roll bar and a full exhaust system making amongst other things, the engine and bay is for all intents and purposes fully finished!




Still to do:

Another attempt at the oil leak

Roll bars need fitting

Battery setup still needs finishing under the rear seat

exhaust need making

tacho needs modifying

centre bearing mounts need making and prop fitting permanently


Lots of progress

Update for this weekend:

Picked up bracketry from powder coaters:


Engine bay masked off and primered where needed then rubbed back down:


Started to build up engine, stroker crank goes in with the machined oil seal sleeve:


I installed all the timing gear to test the Piston - Valve clearance, when I installed the piston I found it hit the crank counter weights on the down stroke so I had to file the piston skirts down about 4 mm, all 6 will need doing ultimately, I had read that the Mahle piston skirts didnt need this doing but my Mahle ones did...




When I turned the engine over the end result shows that the intake valve edge is very close to the piston relief, I will need to get all the pistons machined here other wise they are OK.


No issue with the exhaust valves:


Hopefully I can get these machined for next weekend and get the bottom end finished and ready to go in. I plan to install the bottom end first then add the head once its in the car. I also hope to the the engine bay colour done next weekend.


Engine bay turned out better than I could have hoped for:




Made my radiator mounts and mounted into car:





gapped my rings:


I timed the camshaft using a DTI and an adjustable pulley. It was 5 degrees out as I had the block shaved 0.5 mm to regain some compression from the stroker mods.


Balanced my pistons and rods, then built them up:



assembled the bottom end:


Refitted my pedals, cables, and braking assembly:


Started to fit my underseat battery kit :


Progress and Setbacks:

Finished building up the bottom end and mated the gearbox:


craned it in, at first it went in rather easy



eventually it was home; my annoyance was the radiator, because I didnt cut the plenum and tucked the radiator underneath i had the radiator installed during the engine install, believing that once the engine was in you couldnt get the radiator out. Well such was the tightness of the engine fit I damaged the radiator as I installed it. Subsequently once it was in I realised I could still remove/fit the radiator, so I could have done the engine then fit the radiator without damage. Very annoying. It does prove a point though. I can fit and remove my radiator despite not cutting the plenum and despite what all the nay-sayers say. All it would require is removing the water pump and cam pulley etc.


Some fanciful pics:



I fitted my fuel filter, brake bias valve and the battery from boot cable:


The big set back today has been my engine mounts, my earlier trial fit made me think they were OK but I made a fatal error. I trialled the head without the exhaust manifold. Today I realised my manifold hits the steering linkage :( so the mounts need modification to lean the engine more towards the passenger side and away from the steering box. This will take quite a lot of work next weekend...


Very Busy this long weekend

First I got a boot box which will be very useful for trips out, also the reason the battery has to go under the seats!



Water pump installed with adequate clearance:


Brake resevoir:


I relocated the horns by mounting them through these outer plenum holes that already exist so no cutting:


Head was installed with proper BMW gasket




Timing belt installed:


Rocker Cover Crackle Painted and Lacquered:


Alternator, covers and rocker cover...


Exhaust Manidold, Coil, And water neck installed. I'm in the process of figuring what type of silicone piping I'm going to have to get to mate all the water circuits:


The hard part is the heater pipes the drivers side pipe has to route behind the cylinder head to the other side and with the carb setup there is VERY little space. You can see I have squeezed a pipe just under the gutter and behind the head that I hope will work. It will rub though... :/ I cannot think of a way around this though other than run a pipe all the way under the gearbox and up the other side... :S


Carb trial fit, expansion tank mounted:


I have a clearance issue with the water neck and carbs. Firstly the blue temp sensor has no chance of fitting so I removed it for now. I will still need a 10mm spacer making for the water neck to move it out as the carb spindle is hitting the thermostat housing. I wasnt expecting this as the manifold was made for an early version of this engine. Obviously the water neck design has changed over the years.


Fitted new fuse box, and roughly replaced the 02 loom. Once I get the M20 loom installed and all the electrics working I will have a go at cleaning up these looms and re-wrapping them, no point until I have finished any splicing and re-routing.


Began work on the ECU today. One of the issues with the E30 ECU is this... It is designed to mount on OUR drivers side of the E30 (European Passenger side).All the cables on the E30 loom run along the bulkhead to the other side (our passenger side) about 3 feet, then along the inner wing. For people doing M20 swaps in LHD 02s they put the ECU in the glove box and route the loom as the E30, along the bulk head. I wanted to keep the glove box mounting in my RHD swap, also there is very little room for chunky loom cabling past my carb setup etc too. So I cut through to the glove box at the end of the inner wing, the problem then is, If I use the original E30 fat loom grommet through the bulkhead I would have 3 feet of chunky pointless loom cable in the engine bay to find space for, (the length which normally runs along the bulkhead in the E30!) This loom is big and unwieldy enough as it is! Plus you can see how little space I have in that area.

I thought it would be better to put all the slack in the passenger footwell/glove box area. So what I did in the below picture was, I have cut the shrink on the loom about 2 feet and pulled the ECU power cable (which needs to be in the engine bay) back, then re-wrapped the loom. I also cut the big grommet and moved that along a good distance so now all the slack will be in the footwell area. I should be able to tie it up out of the way under the dash somewhere. Slightly annoyed I had to cut the grommet but there was no other way to move it.


So thats up to date... Its looking relatively complete but theres still a good way to go....

Battery Set up

ECU installation



Rear Brakes

Bleeding clutch and brakes

Ignition leads and system

coolant hose setup

and a myriad of minor things that escape me


Engine Build Begins

OK, so heres the engine build so far...

First I accidentally bought this late 1988 325is engine with 1.3 Motronic and all the ancillaries:


Then this M50 328i crank:


Then these 130mm rods:


Stripping engine down (yes, that is an Elan 2 Plus behind me!):


M10 removed and engine bay removed of as much as possible (servos etc)... you can see 40 years of crap in here, also you can see the lower inner wings and bulkhead are still the original Colorado? colour... obviously the car was resprayed without pulling anything from the engine bay, something I will have to correct whilst I'm in there (mission creep already!):


Cylinder head was stripped, nearly all the rockers were pitted on the cam face. I sent it out for machining, the exhaust guides needed replacing, a broken stud removing, one valve was bent, and it needed a little bit of welding for corrosion around a firing ring. I got a full set of goodies to reassemble the head including a 285/285 Catcams Camshaft. The E30Zone cylinder head rebuild guide was invaluable here:



All Done:


Meanwhile lots of engine bay work has been going on, here it is nearly all rubbed down and ready for paint, still requires masking off etc Im going to have to paint around the steering column as removal is a lot of hassle Im not expecting a show quality finish, whatever I do it'll be a lot better than it was before:


A couple of holes in the bulkhead are necessary, the big one for the E30 loom grommet to the ECU in the glove box, the smaller one for the E30 battery in boot cable grommet:


I did some playing with the radiator, my first plan was to use the below radiator from a 1988 520i Automatic M20b20 car. 1) It is made for the M20 2) It has a built in coolant reservoir, 3) it has a built in oil cooler (originally for the automatic gearbox). I was planning on cutting out the front plenum to fit the radiator as with all M20 installs, then doing a lot of fabbing to make it look like a professional job as best as possible. However once I cut the stock radiator slot wide enough I realised I can tuck the M20 radiator up underneath the plenum at an angle and not have to cut it at all which will look much nicer. The downside is 1) I cannot fill the radiator, and 2) it will probably sit below the engine causing air pockets. These can be resolved by going to the Mk1 Scirocco radiator with an expansion tank like the E30 originally had.

This leaves the remaining issue which is that once the engine is in place the radiator cannot be removed. A semi-major problem. However, if I buy a brand new scirocco radiator I would expect it to give me many years (even decades) hassle free use, even if it does develop a small leak I could use some coolant sealant stuff to fix it. It would have to be quite a large radiator leak to necessitate me removing it altogether... Personally I think its worth the risk...



So now its time to trial fit the block to see how good the engine mounts I bought are, they are pretty good, it mounts about as far back as possible, but it leans a bit too much to the drivers side. I plan to mod the passenger side mount slightly to lower it on that side. Whilst in there I checked if the water pump would fit with the radiator leaned under the plenum, I have no picture but it fits without concern a good inch or 2 clearance.



Now my original plan was to keep the injection system, power and efficiency and all that.... However we all know nothing beats the sound and look of carbs so when this set of triple 44IDFs mounted to a super rare VGS M20 manifold ported for a 2.5l head suddenly appeared for sale they pulled at my heartstrings. Heart won over head so carbs it is... :D


Some history about the VGS system can be found here:


Essentially it is a very rare triple carb system made for the E21 320/6 in the very short period before the 323i came out. This link says only 13 were made but I cannot verify anything. Any more info/pictures on this from anyone would be great.

I would love it if someone could translate the article for me in the above link ;)

Here is a video of the system in operation:


So here it is mocked on my empty block:



And now you are all up to date, the engine is now back out, I still need to:

Paint engine bay

Install Scirocco Radiator

Re-install brakes with new lines

Build up engine

Fabricate (very) short shifter platform

Create rear gearbox mount

Sort out the propshaft and centre bearing mounts

Do all the wiring in

Build custom exhaust system


Lazy Me!

Hey All,

I am very lazy but thought I might get around to sharing some pics of my winter project so far, it all started when I accidentally bought some M20 mounts and an M50 328i crank. These terrible accidents happen sometimes...

First off, say hello to my '02, Dec '71, one time Colorado, at some point resprayed Inka...


Anyway first thing was first, I needed a diff to take the torque, some say its not necessary, but fabbing my own diff into the 02 seemed a easy way of getting a cheap LSDs also, 2 birds one stone. I was running 3.91 diff but with the M20 I thought I'd go back to 3.64 so my speedo will read correctly again, '87 and earlier E30 325is came with these diffs. Now the easy way, as you know, is the E30 rear beam modified and ending up with with wider track and turbo arches. However as we all know, turbo arches look shite on anything other than turbos and track dedicated cars :o . There was no way I would butcher the exterior of my 02 for this, so I had to modify the existing beam and hangar. I got lots of help from couttsdesign for this!

Original Beam and diff, I welded locators for the centre of the output flanges


Hack off the stock diff mount and place in the Med case diff


Take lots of measurements and cut some metal:


Fine tune the design:


Weld together:



Slot beam:


Weld together and powder coat:


Design rear hangar brackets after trial fitment:



Build up for install:


Diff installed:


Next up I'll get around to where I'm up to with the engine....