Building an M42

[I8UR911]

Scored a M44 crank and con rods for $100 shipped. That's cheap enough for me to be all in for a stroker build :)

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[I8UR911]

Received lots of parts recently; 279/274 cams, Supertech valve spring kit, VW lifters, M20 starter, M44 crank and conrods and 19lb 4 pintle Bosch injectors..... dropped off M20 flywheel at machine shop to be lightened and resurfaced. Time to order pistons (87mm with 11:1 comp ratio), bearings and get ready for more machine work.

Thinking about contacting MM to see if they'll sell me the chip they use for their M42 Rally engine.....????

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[joolz635]

sounding very similar to my build. Would you consider just going for a stand alone computer? More $$$ obviously but much better for tuning.

[wazzu70]

Just an FYI, the M20 starter will not fit the M42. Just making sure you are planning on gutting it to get the pinion gear assembly.

[joolz635]

Just an FYI, the M20 starter will not fit the M42. Just making sure you are planning on gutting it to get the pinion gear assembly.

WRONG.... i have just fitted an M20 starter to my M42 with NO modifications at all. You just need to get a late model M20 starter that has a smaller case.

[carnurd]

I'm planning on doing pistons(12:1) and rods sometime soon along with ITB's and a Haltech plat sport 1000. Currently in my engine, SS +1 valves, 279 VAC cams, dual sport springs, hardened retainers(might swap to Ti when I build), alum flywheel, crank has had thrust surface fixed welded and nitrided.

Car is in desperate need for intake cfm at high rpm (greater than 6000rpm). ITB's will fix that along with the Haltech, then maybe in the future look at replacing the hydraulic valvetrain with solid lifters and going big on cams(300+ duration why not ;)..)

[wazzu70]

WRONG.... i have just fitted an M20 starter to my M42 with NO modifications at all. You just need to get a late model M20 starter that has a smaller case.

Gotcha. My M20 starter dod not fit but I was unaware there were different casings.

[bmwman91]

Gotcha. My M20 starter dod not fit but I was unaware there were different casings.

Yeah, the post '89 ones seem to fit fine. I bought one from a buy on r3v to get the M20 pinion gear, and when I got the M42 and M20 units side by side they were basically identical. I swapped the gear anyway though because the M20 starter internals were pretty trashed whereas I had already cleaned & prepped the M42 one.

[wazzu70]

Dang, wish I knew that two years ago! Oh well :)

[I8UR911]

Just installed my AFR gauge today. Wanted to see where the car ran with just a JC chip to get a base.....14.2-14.6.

Hopefully I'll be getting the head soon from the machine shop...taking FOREVER.

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[steveo777]

Not stroking dose not really have any down sides besides less power, but if you have the money a short stroke allows high HP which can make up for the lack in displacement.

I just dyno my car I would post a picture and video but my camera broke so there is nothing at the moment. But I pulled 93.5kw at the wheels which is about 125hp all I have done to my m42 is a chip, CIA and radius valve seats.

A good port job some wild cams and maybe a slight increase in compression with a bigger bore should see you easily make 175-180hp at the fly even 200hp at the fly. The M42 is not a bad engine just requires more attention to detail, planning and money to get power out of it.

If the engine was shit then why did they swap from a S14 to an S42 in the touring car E36? It is no M20 M50 S50 but it has its part and that part fits perfectly in my life.

it'd be really tough to get 200bhp from this motor without heavy heavy work (naturally aspirated) just look at the metric mechanic m42 http://www.metricmechanic.com/produc...gines/m42-m44/

its 205bhp at 2.1L

I own a 91 318iC and I love the m42 for what it is: an efficient, happy to rev, little motor. it definitely will benefit from a chip and some other basic bolt on mods, but if you're looking for the best bang for your buck you really should just swap in a bigger motor

with so many motors having already been shoehorned in, doing it is as simple as following in many others footsteps

just my $0.02

[bmwman91]

it'd be really tough to get 200bhp from this motor without heavy heavy work (naturally aspirated) just look at the metric mechanic m42 http://www.metricmechanic.com/produc...gines/m42-m44/

its 205bhp at 2.1L

I own a 91 318iC and I love the m42 for what it is: an efficient, happy to rev, little motor. it definitely will benefit from a chip and some other basic bolt on mods, but if you're looking for the best bang for your buck you really should just swap in a bigger motor

with so many motors having already been shoehorned in, doing it is as simple as following in many others footsteps

just my $0.02

I have a fully loaded 2.1L MM M42 in mine. Hell, there are even a couple of things in it that aren't in that brochure. A 200bHP+ M42 is nice. They said that it can take 9000RPM fine, but since I told them I wanted another 200k miles out of the car they capped the chip's rev limiter at 7700RPM. There have been reports about the M42's harmonic crank damper coming apart above 7000RPM, but MM said that they had never seen it. When I take mine over 7000RPM there is definitely a vibration that starts to kick in, so maybe people took that as a bad sign.

[I8UR911]

it'd be really tough to get 200bhp from this motor without heavy heavy work (naturally aspirated) just look at the metric mechanic m42 http://www.metricmechanic.com/produc...gines/m42-m44/

its 205bhp at 2.1L

I own a 91 318iC and I love the m42 for what it is: an efficient, happy to rev, little motor. it definitely will benefit from a chip and some other basic bolt on mods, but if you're looking for the best bang for your buck you really should just swap in a bigger motor

with so many motors having already been shoehorned in, doing it is as simple as following in many others footsteps

just my $0.02

M5x/S5x swaps are boring and I've already done those. After driving my 318is (street, auto-x and track), I've found that this car is better balanced than a swapped car.....as I'm sure many people know. I'm not looking to build a "fast" car, but I am looking to build a "quick" car. If I can be in the 160-180hp range (to the wheels) and rev between 7500-8000rpm, then I'll be a happy camper. This car should feel as quick as my last swapped car, BUT much better balanced.



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[Dj Buttchug]

total cost spent on engine parts already?

[RobertC]

WRONG.... i have just fitted an M20 starter to my M42 with NO modifications at all. You just need to get a late model M20 starter that has a smaller case.

Nice, I was under the impression that you had to change the pinion gear.

Good to hear someone has broken the myth.

To the OP:

Don't forget to order new gears for the cams and crank. Typically the idler is just fine as its a pretty damn stout gear.

The updated crank gear has rubber banding around it to suppress vibration, and most stock cam gears are typically shot. If your cam gears are sharp points then they are shot. You should have about a 1mm flat on the tip of each gear. Also get a new chain, they do stretch.

Timing case cover. I have seen these corrode heavily on the backside. They share both coolant and oil passages in the gasket. I have had to actually machine the front face of the block due to corrosion damage.

Oil Pump and Relief Valve. I have been able to purchase all new pump parts from the dealer. The original oil relief valve was steel while the cover was aluminum. I have seen the relief valve seize and the engine will lose oil pressure so fast your rod will come out of the block and kick your starter right in the balls blowing the case apart. You might just find the wrist pin blew right through the side of the air box. So to prevent this little bit of nasty violence, replace the oil pressure valve and spring. The new valve is made of a black nylon/plastic material. Make sure to get the spring with the valve as it is different from the original.

Just a few things to think about to make sure your build actually stays together.

PS: I have a Ford Duratech 2.3 all aluminum block sitting in the shop for someday when I have time and money, someday.....