I am someone who, after years, is pulling their PJ noisey out for a cloyes true roller. I think the accuracy of the gear drive is a misnomer. ...
... I really believe a gear drive these days is strickly for noise and do not provide accuracy in timing over today's true double rollers.
agree with everything 'Dub' said
the OEM cam drive systems were not up to the task of driving HP cam systems and the use of a gear drive was the only way we could get a cam drive system to hold up under high loads (placed on them by higher valve train rates, higher oil systems demands and ...) and rapid transition RPM use in high performance endurance engines.
The 'match-race' guys still stuck with chains, as most the gear systems added more issues than they cured ... You'd never see a Gear Drive in a "Grumpy" or any other 'name' engine at any drag strip
They are not more 'accurate' at all - they induce odd harmonics and resonance into the systems that can not be easily dealt with, and will be detrimental to the overall performance and life of most engines.
We didn't like some of the other problems they added to the mix - spark scatter, cam wear, additional heat load, ... - but they were the only game in town
for quite some time in serious performance endurance engines.
In a modern performance endurance engine - they have no place
We now have chain and belt systems that are well suited for our needs and way capable of handling any cam load demands we can put on them.
Don't get me wrong, I still at times use one in an engine - but those are marine builds that require something other than a standard drive system ...
There's really only one reason to spec. one for a street driven vehicle these days - but stating that would most likely be seen as "bashing"