Building an M42

[I8UR911]

total cost spent on engine parts already?

I'll have roughly $3k-$3500 into the motor when done.

Sounds like a lot, but it'll essentially be a brand new motor.....new bearings, seals, pistons, rings, gaskets, injectors are rebuilt, valve springs are new, etc.

IMO a much better value than buying a used, unknown history, M5x/S5x.

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[I8UR911]

RobertC thanks for the tips. I will definitely keep those items on the "short list". I'll do any of these minor replacements to ensure that all these money isn't blown (no pun intended).

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[Dj Buttchug]

I'll have roughly $3k-$3500 into the motor when done.

Sounds like a lot, but it'll essentially be a brand new motor.....new bearings, seals, pistons, rings, gaskets, injectors are rebuilt, valve springs are new, etc.

IMO a much better value than buying a used, unknown history, M5x/S5x.

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figured as thats about what I have into mine. GL with this build. will be watching.

[totheredline]

what is this I hear that euro s50 solid lifters will fit in m42 cam trays?

[bmwman91]

You can try emailing Metric Mechanic to ask which lifters to use. I'd be wary of solid ones because you need to manually adjust them regularly. MM stuck M/S5x hydraulic lifters of some sort in mine, and they are supposed to be the lightest 35mm ones that you can put in there (MUCH smaller oil reservoir in the lifter than the stock ones). I just can't remember where they were from.

If you want to REALLY go light, you can actually retrofit the smaller diameter S50 lifters and cam trays into an M42.

http://www.youtube.com/watch?v=ynVBlDMow3k

The thing is that high lift cams + small directly actuated bucket lifters can = chewed up cam lobes. You absolutely MUST run a high quality synthetic oil with high levels of ZDDP. Mobil 1 15W-50 and Castrol 10W-60 TWS are the only ones that I can really recommend, and they were they only two that did well in MM's oil tests. It complicates things for break-in when you are supposed to use dino oil, but a lot of people have seated their rings fine with synthetic I think.

[wazzu70]

IIRC the Euro S50 solid buckets are too small of a diameter to work.

There is an "updated" lifter for the M5x family that fits our cam trays and is lighter but I cannot recall the correct dates off the top of my head.

IMO, going with a modified cam tray to fit the smaller M5x hydraulic lifters is the best route for most people unless the car is strictly a race car. With solid lifters you really need to use a cam profile made for them or else you dont see much benefit.

Upgrading the valve springs and going with the smaller lifters is a great combo for most available cam profiles.

[MF DOOM]

Call Jim at MM. He'll answer any question you have with GREAT detail. Just make sure you have time. My calls usually stretch to an hour+. IIRC, they use a stiffer internal spring on their m42 hydraulic lifters, among other things. Theyre good for 7700+rpm. What more do you want?

bmwman91, you have a factory intake and tb on your car, correct? Did MM modify it in anyway?

EDIT: Just looked at their m42 booklet and saw the pulse chamber.

[totheredline]

This thread is interesting. http://www.r3vlimited.com/board/showthread.php?t=46060



Im really thinking about picking up an M42 for $300 at the junkyard and strip it down and dick with it a little and rebuild it for when I eventually find a decent 318is

[MF DOOM]

Theres nothing wrong with the factory harmonic balancer. Just a myth.



Any updates, I8UR911?

[bmwman91]

Call Jim at MM. He'll answer any question you have with GREAT detail. Just make sure you have time. My calls usually stretch to an hour+. IIRC, they use a stiffer internal spring on their m42 hydraulic lifters, among other things. Theyre good for 7700+rpm. What more do you want?

bmwman91, you have a factory intake and tb on your car, correct? Did MM modify it in anyway?

EDIT: Just looked at their m42 booklet and saw the pulse chamber.

Yup, got the PC intake. While I would like to just go ITB, I don't feel like swapping crap around every couple of years to pass SMOG. The whole idea behind my MM engine purchase was to get a big bump in power while having a relatively maintenance-free engine for the long term. The car has plenty of mid-range torque now, especially considering the fairly aggressive cams that are in there.

+1 on calling Jim. He's a good guy that likes to talk cars.

Also, for those considering the ~33mm lifters from the later model S50 engine, you NEED to run oil with high ZDDP content. Your cam lobes will be destroyed if you don't. High lift cams already have issues with the stock diameter lifters if you use the wrong oil, as I learned the hard way.

[Swanny]

Awesome! My friend katfish is looking to do a pretty solid m42 build and I'll make sure he gets an eye on this thread.

Good things are happening in here!

[wazzu70]

This thread is interesting. http://www.r3vlimited.com/board/showthread.php?t=46060



Im really thinking about picking up an M42 for $300 at the junkyard and strip it down and dick with it a little and rebuild it for when I eventually find a decent 318is

That thread is full of a bunch of asshats who don't know what they are talking about!

The only person with any sense is e9nine

[bmwman91]

Per Jim at MM, a built M42 can handle brief ventures to 9000RPM with hydraulic lifters and the stock harmonic balancer. I had them limit mine to 7700RPM in the software because I want to drive this thing for a LONG time. If you put in lighter valvetrain and bottom end components, and carefully select your valve springs to apply the minimum required pre-load, you can build a high revving M42 without solid lifters. I mean, you probably need to be even more careful about the spring pressure with solid ones, and you MUST get a custom cam profile intended for solid ones to use them effectively.

[decay]

While I would like to just go ITB, I don't feel like swapping crap around every couple of years to pass SMOG.

FWIW, the last smog guy i went to in December didn't even blink at my ITB setup; just made sure the required equipment was still there and dyno'd it.

the time before that, in 2010, was a "this is an M3, right? *wink*nudge*" kinda deal (though admittedly it took trying 4 shops).

so yeah, i understand not wanting to deal with it, but i think our cars are getting to the age where the techs don't necessarily know what's supposed to be there.

[bmwman91]

Haha nice. I gotta find one of those shops. Honestly, it is retarded that CA does a visual inspection. Just run the exhaust sniffer, pressure test the gas cap and evap system. Done.