m42 build up...

[chrisbec]

Nice clean work! I love the look of clean freshly machined engine parts all neatly orgainzed .

I think it is interesting that the m42/44 blocks can be opened up to 87mm or even 88mm. Much of the info I read on the net about m50's say not to open then up even to 86mm since the cylinder walls become very thin particurlary on the newer M50tu blocks and they may crack. That is not to say that modifying the M42 like that is wrong or anything because it seems like it has been done many times successfully.
Some say the older M50 block castings are thicker around the cylinders. Like a lot of info on the net who knows what to believe without real numbers of trustworthy experience talking . Not like any of those guys provided ultrasonic measurement data for comparison sake or anything like that, it is mostly all just talk...

[Banggotan]

I am really sorry to bring up a very old thread. I am trying to find what I need through searching but bo luck yet.

I have built an M44 with M42 head (n/a) , it was making 150whp on dynodynamics.

Specs was s52 pistons decked and pocketed
Cams were catcams 300 deg + vac springs
Acl bearings
Arp studs
Etc

However the engine did not last long. During practice laps, engine lost oil pressure after only 3 laps.

Damage list:
Cracked piston pockets and cracked cam journals housing.
Valves has 2mm clearance to pistons during opening.
But it seems the valves are floating and hitting the piston pocket.

What I wanted to know about is there a good resource to buid an M44/M42 NA ? Interested in custom 11:1 compression je piston you use in this thread, and wanting to relearn how to set up the cylinder head to match the high comp pistons.

Thanks in advance
-Rey