I recently rebuilt my entire rally headlight system on my 69 Z/28 RS and replaced all the washers, bushings, etc. I used lithium grease on all the moveable parts. The doors now work but there is quite a lag between the time one door opens/closes and the other opens/closes. They also seem to be struggling a bit. I was curious if this is the way I should expect it to be or maybe I have another problem I've overlooked. Also, the vacuum on my 302 has consistently been low (around 5-8) but the vacuum canister does seem to be alright. I know this because when I turn the car off and use the manual open/close switch, I can usually get another open/close cycle out of the residual vacuum. Thanks in advance for your insight.
I think if you solve the low vacuum problem everything else will fix itself. First make sure you don't have any vacuum leaks. Check all the hoses, canisters, base of the carb, etc. If you can't find any leaks try retuning the engine and carb. Even with a lumpy solid lifter cam 5-8 inches of vacuum seems low.
I installed a RS grille kit from Classic, the left door opens and closes slower then the right door, can't find any leaks or any other problem. I even switched vacuum canisters to see if one worked better then the other, was still slow on the left side
I'm not sure if it gets any better than that. I don't think even when these cars were brand new that they opened at the same time. For now, at least I know someone elses car does the same thing and since they work, I'm happy with that.