compyelc4
Well-known member
- Joined
- May 1, 2002
- Messages
- 609
- Location
- Dayton, Ohio
- Corvette
- '95 LT1 Coupe, Comp Yell; C6 Roadster, Vel Yell
Can one of you with a '95/'96 LT1 do me a huge favor? Can you tell me how many inches of vacuum you are getting at the air intake end of your Opti-spark "fresh air" system. I can't seem to get over 1-2" of mercury! That isn't enough to respirate a flea, much less help vent the Opti.
The measuring point you will be looking for is at the "L" shaped light grey vacuum nipple that pushes into a hole in your air intake. That is the point where manifold vacuum draws fresh air into your Opti. I doubt you will measure full vacuum.
For some reason I was thinking that full intake manifold vacuum would be plenty to keep the inside of the Opti dry, but on second thought that could not be because the system can't allow full intake vacuum to go unchecked or the system would detect that as a significant leak (lean condition) and boost up the idle too high.
The vacuum line, on its way to the Opti, is "governed" by 2 check valves. The first is an itty-bitty blue and white plantic thingy that does allow full vacuum to pass through (in one direction only). The second one, on down stream, is larger (1-1/2" dia.). It looks like it has a metal restrictor plug in its intake. I can only draw a very small amount of air through that thing (AND I DON'T SMOKE). I think that is where the main restriction is! That restriction is so small that it will not even allow me to pass a very thin needle through it. I think it may be designed that way so the intake does not lose so much of its vacuum. So... if that hole is to restrict vacuum pull that much how can it begin to keep the Opti dry? Your vacuum check may help me reason out this problem. I WILL NOT LOSE A THIRD NEW OPTI IN 1 YEAR. My water pump had a slow leak. The Opti was not kept dry internally cause the vacuum hose that runs off the front of the manifold had a 90 degree kink in it and was allowing NO vacuum to help purge the moisture from the Opti. I would like to at least make sure that this fresh air system is working right this time.
Thanks a bunch for listening.
Ted
The measuring point you will be looking for is at the "L" shaped light grey vacuum nipple that pushes into a hole in your air intake. That is the point where manifold vacuum draws fresh air into your Opti. I doubt you will measure full vacuum.
For some reason I was thinking that full intake manifold vacuum would be plenty to keep the inside of the Opti dry, but on second thought that could not be because the system can't allow full intake vacuum to go unchecked or the system would detect that as a significant leak (lean condition) and boost up the idle too high.
The vacuum line, on its way to the Opti, is "governed" by 2 check valves. The first is an itty-bitty blue and white plantic thingy that does allow full vacuum to pass through (in one direction only). The second one, on down stream, is larger (1-1/2" dia.). It looks like it has a metal restrictor plug in its intake. I can only draw a very small amount of air through that thing (AND I DON'T SMOKE). I think that is where the main restriction is! That restriction is so small that it will not even allow me to pass a very thin needle through it. I think it may be designed that way so the intake does not lose so much of its vacuum. So... if that hole is to restrict vacuum pull that much how can it begin to keep the Opti dry? Your vacuum check may help me reason out this problem. I WILL NOT LOSE A THIRD NEW OPTI IN 1 YEAR. My water pump had a slow leak. The Opti was not kept dry internally cause the vacuum hose that runs off the front of the manifold had a 90 degree kink in it and was allowing NO vacuum to help purge the moisture from the Opti. I would like to at least make sure that this fresh air system is working right this time.
Thanks a bunch for listening.
Ted
