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I am trying to figure out the vacuum diagram on my 1984 corvette, 5.7L, automatic. Is there somewhere that I can get a diagram/schematic for this. So far it is a mystery to me.
I am trying to figure out the vacuum diagram on my 1984 corvette, 5.7L, automatic. Is there somewhere that I can get a diagram/schematic for this. So far it is a mystery to me.
my name is drew#46, I'am doing the same thing on my 84 l83 motor
I haven't been able to find anything yet, was wondering if you have had any luck?
That's the same diagram that's on the radiator shroud of my '84. But that leads me to a question about the vacuum routing I've never been able to figure out: There are two vacuum motors on the two air inlets to the air cleaner, but only one of those vacuum motors are controlled by the temperature sensor, the one for the warm air tube. Does anybody know why the other one would be routed directly to the throttle body vacuum? I would think this inlet air path should stay open unless the engine is very cold.
Since this is an educational thread about the '84 vacuum routing, I hope this isn't considered a "hijack question".
That's a good question! "I GOT THIS!" -followed by a loud bang, and a muffled scream
My guess is that the passenger's side closes off completely when there is vacuum, forcing all the air to enter the filter housing through the driver's side only; hot air pipe when cold and through the driver's side "cold air" pipe when hot...opening the throttle (depleting vacuum), opens both flaps pulling through the (semi) CAI hood ducts.
Phallet and Drew, have you figured out your vacuum hose routing? Where are you having trouble?
Tom, I'd say you're right on how the air cleaner vacuum motors work, but that doesn't answer why. I decided to do some investigation on my '84. I discovered that my passenger side vacuum motor has a busted diaphragm, so that side never closes! So I'm drawing nice fresh, cool air thru both hood ducts all the time! No wonder the car runs so good!
That explains why I have no trouble keeping up with a multitude of ZR-1's and a certain hot rod 409!
Tom, I'd say you're right on how the air cleaner vacuum motors work, but that doesn't answer why. I decided to do some investigation on my '84. I discovered that my passenger side vacuum motor has a busted diaphragm, so that side never closes! So I'm drawing nice fresh, cool air thru both hood ducts all the time! No wonder the car runs so good!
Sure it does! You know the principle of the heat stove; to draw hot air in when the engine is first started, (cold), to help vaporize fuel better. Most cars have one filter inlet, so you have one valve, temp & vacuum actuated. You car has TWO inlets (which is why it keeps up w/ZR-1's!) so if we only closed the driver's side, we'd still be sucking cold air through our passenger's side hood CAI...dramatically diluting our hot air just when we need it to be the hottest. SO, we throw in another flap in the passenger's side that closes w/vacuum.
Now, any time we're at idle, vacuum closes the passenger's flap, we're drawing all air through the driver's side...and that side determines air temp through the thermactor temp vacuum switch. If motor is cold, all of that driver's side air will be heated, if the engine is warm all of that driver's side air will be cold, though the hood.
One inlet is probably way more than enough to feed a stock L83...but still, when you go to WOT, you get both flaps open, feeding MASSIVE, COLD, ZR-1 BEATING air into the filter housing!
Last edited by Tom400CFI; Oct 19, 2015 at 10:39 PM.
One inlet is probably way more than enough to feed a stock L83...but still, when you go to WOT, you get both flaps open, feeding MASSIVE, COLD, ZR-1 BEATING air into the filter housing!
That explains why I have no trouble keeping up with a multitude of ZR-1's and a certain hot rod 409!
Oh, we were having a contest? Yeah, your car runs fantastically.
I spoke with my old tuner, Gary, and he loves to tell the story about how he drag-raced a well-known Corvette engineer at a national Corvette gathering. That engr. always brought the soon-to-be-released new model year Corvette, for show and intro, in this case an '89.
That slightly modified '84, with a TBI similar to yours, Roy, beat the '89 TPI handily.
