I sold a friend a Mopar Purple Shaft 284 street hemi grind for a 383 motor going into a 1968 Charger with power brakes, he owned a automotive garage and it was for one of his bigger commercial customers Son car. I help him degree it, it had right at 4.5 inches of vacuum idling at 850 RPM in gear
That's strange... must have been something else wrong since you degreed it for him. Huge vacuum leak maybe? I put that exact same Purple Shaft cam (284/.484) in my basically stock 383 rebuild. It idled with a very minor lope at 13" vacuum at 750 rpm!
I was told by a local Mopar Purple shaft lover, he is very knowledgeable on Mopar V8 B&RB motors
, that Ma Mopar had change the LSA on that camshaft, RB&B motor street hemi 284, 484 grind back in the mid 1990s or so
I bought several other Mopar brand camshaft later before abandoning them all due to the "590" grind not having .590 net lift
I called them, Mopar hot line, about it and I was told they had change vendors and they knew it wasn't .590 net lift now but they had dyno the cam and they weren't worried about the loss of .040 lift
