M70/M73 hydraulic lifters in M20 to eliminate need for valve adjustments

[ZeKahr]

Not planning to do this on my M20 (unless its verified this actually works) but I’m curious: has anyone on here ever attempted to install M70/73 hydraulic lifters on an M20 engine to eliminate the need for valve adjustments? Or is the lifter design on the M70/73 not compatible with the M20 valvetrain?

Would be interesting to see someone who has a spare engine attempt this and share results

[varg]

M7X heads are more like M40 than M20.

[ZeKahr]

M7X heads are more like M40 than M20.

Makes sense. I read the M7x designs were based on the M20.

[varg]

I had always heard that too but I think it's a misconception. The more you look at them the more you realize how little they have in common other than 2V, multiple of 6, timing belt. The M7X and M40 had some stopgap SOHC design that was probably lower maintenance and quieter than an M20 but looks crap for high revs, the M40 didn't survive long before being replaced by a superior DOHC and I bet the M7X only stuck around so long because of how huge a DOHC V12 is and how crazy expensive it was going to be to develop one when the low revving SOHC M70 suited luxobarges perfectly well. I bet the only reason it used twin motronic ECUs is that Bosch didn't offer a single EFI setup that supported 12 cylinders, other V12s of the era (when not carbureted) used (twin) K-jet or derivatives.