The 15 Y/O Turbo M42 Build Thread (Now Holley EFI Terminator X Controlled)

[varg]

M42s never looked so good.

[2mAn]

Looks a million bucks

Yea... freaking brand new!

[econti]

Looks a million bucks

[Dj Buttchug]

Getting closer now.

[Dj Buttchug]

Did the old school by hand valve lapping. Took about 1.5 hours per cylinder.


All parts cleaned up and installed. One more step to a reconditioned long block.

[mike.bmw]

Beautiful. Absolutely beautiful. This made my day, thanks!

[Dj Buttchug]

What's compression on it now?

Same 8.5 to 1. As its always been.

[econti]

What's compression on it now?

[Dj Buttchug]

Re-honed and decked. New pistons and rings.

Short block is back together now. Rods and pistons balanced within .47g

Top ring gap .0195
Bottom ring gap .0235
Cerakote block (burnt bronze)
New freeze plugs


Spins like buttah.

[Il Duce]

Jesus, it's beautiful.

[Dj Buttchug]

What a sight to behold.

A brand new M42 Cylinder head.

17 units left in the world per BMW apparently.

$2,900 OTD

[Dj Buttchug]

Was it running quite lean at any point?

Not since I installed the new engine management. Lean conditions could have been present during my Mega squirt days. I had a lot of troubles getting the car to run correctly in the beginning. The skirts on each piston have a some slight wear on each side indicating some issues.

[econti]

Was it running quite lean at any point?

[Dj Buttchug]

All because of a $12 spark plug

Brings back some memories of building this engine when I was in tech school.

Some scoring on my cylinder walls is a bit unsettling. There are areas on cylinder 1 and 4. The majority of damage is in hole 3 where the plug dropped. All areas are .002 or slightly deeper :(

I have a new set of pistons and rings. We will do the same treatment as the m50. Cerakoted block and components. New oil squirters, the works. Crank, rods, and all bearings are in great shape so that is good news.

It will be better than it was. I'm pissed, but it's not the end of this car. The M42 will live on.

Here are a few photos.

[2mAn]

No luck on the WTB here? Bummer...