I would think it would be dependent upon the amount of vacuum made from the source.
I thought, just by reading this site, that '67 RS's only had vacuum mechanisms.
My thoughts are these, the door assy with the least resistance in movement will move first, when that's done, the other door will open.
Could be the camshaft is other than stock, vacuum gauge should show between 18-21 inches of vacuum. The bigger the cam, the less vacuum. Or maybe the source is from the wrong place, an intake runner rather than the plenun under the carb.
You could always hook up an 20-30 gal air tank to an A/C vacuum pump and hook the supply hose to the door assys for troubleshooting rather than waste gas from the engine.
Yes, it's perfectly normal for one to open part-way or fully before the other. You can try switching the springs to see if they reverse order or get closer.
Why do you think you have a vacuum leak? If you isolate the servo motor(s) and connect a hand vacuum pump to it you can pull the unit open and observe the bleed-down to see if there is a leak in the servo. You can also do the old tried-and-true method of sucking on a piece of hose hooked to the servo and see if it is leaking badly.
Check the hose system over carefully and replace any (or all) of the hose(s) if they look brittle or cracked.
GM used Electric RS Doors on '67's and Vaccuum on '68 & '69's.
Everett, the 67's had electric motor opening system. Some guys replace that with vacuum, but original is electric.. the 68 and 69's have vacuum setups. My (69) opens one at a time too but Ive not yet tackled that project to even them out. I will wait for winter again for that.
69RS 350/255 LM1,TH350,Dover White,Blue Vinyl top
F&R spoilers,pdb,ps,am/fm,4.10 Posi.,A/C,
fold down rear seat.
My RS www.brainerd.net/~knudsen/69RS
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