[Frank Lee]

Most interesting report, tele. I think it is "didn't" like, though. They did it 32 years ago on old-school carb'd cars... oddly enough, they complained about the kit's lack of a means of deactivating individual injectors on injected cars which to me would be about 100x easier to do than fooling with the carb on the carb'd ones, and of course the injected cars have so much more mixture self-correcting ability as well.

They mentioned other deactivation systems too dating back to at least 1974; one from Michigan State University, and the Eaton/Cadillac showed different emissions reactions to deactivation. I wouldn't worry about any of it, since I wouldn't try it on carb'd equipment.

They identified many operational shortcomings: somewhat harder starting, stalling, poor acceleration, really not much better fe under any but steady-state cruise conditions, dieseling on shut-down, etc. that the new-gen DoD addresses by basically only deactivating under low-load steady-state cruise. Both old and new DoD seem to have settled on about a 15-20% potential fe improvement at cruise.

I thought it was interesting that they went through so much work to couple the lifter to the pushrod and hold it away from the cam when deactivated. I wonder if harm would come from just letting the lifter and pushrod float i.e. more or less ding around at "top of the lobe" height with only gravity wanting to lower them into contact with the lobe? Or even go the other direction and keep the pushrod and lifter in constant contact with the lobe, deactivated or not.

P.S. There was a lot of cylinder deactivating work going on after 1973; I recall an article in The Mother Earth News detailing how to shut 4 off on an 8 (which I now doubt worked at all since IIRC it didn't alter the valves at all- it was a "barrel valve" in the intake- so the pumping losses remained) and also I recall seeing Mankato State University's "50/50 VW Bug" (named for achieving 50 mpg at 50 mph) via 2 cylinder VW engine mod.