Is the TH46 really that bad? In a word no.

But it is a bit tempermental. Like already mentioned
the needle adjustments are a bit sensitive so its easy
for the average "needle tweaker" to miss the sweet spot.

I think where most guys go wrong with this engine is
inadequate break in. Its very tight so needs considerable
time for break in. What they end up doing is run it a little
on the ground then set it just slightly rich and fling it up
in the air. It then proceeds to lean out in the air, overheat,
and usually die. After a few deadsticks the owner proclaims
the engine junk. Usually with less than two or 3 tanks of
fuel through it.

You can get by with this with most OS engines but others
Like the Tower require a little more care.

They lean out a lot in the air. More so than most other engines.
And the needles interact. They are screamers once you get
them dialed in correctly.

Mike Hammer