[rotorwrench]

The shroud is one problem. You can't put them front to back and use any type of air filtration so that was one problem. The 4-bolt vs 3-bolt pattern, as mentioned, is a work around problem. No manifolds were made for them in a dual capacity that would work well.

They make the old Mercs run well enough but they can be more difficult to find good cores for replacement parts. Many have been warped & bent due to to mishandling and shade tree over torque of fasteners. Folks don't understand them, so they don't generally try to use them. If you have a poor fitting float bowl, they like to leak. If the shroud doesn't fit the base very well, the power valve won't work right due to vacuum leaks. There was a time when parts were very hard to find too. I like them but then I understand their ups & downs pretty well.