opti spark help
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
GM added the vent system when they realized the ozone generated by the high voltage spark was causing corrosion and premature failure in the UNVENTED Optis. Why undo one of the more positive changes that GM made.
One line is a filtered/MAF measured air supply line, the other is a vacuum line, with a check valve and a filter.
One line is a filtered/MAF measured air supply line, the other is a vacuum line, with a check valve and a filter.
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Joined: Jun 2000
Posts: 857
From: Washington, Michigan USA
First off, (and as others have hinted at above), there are NOT two(2) vacuum lines on a vented Opti. The line from the die cast aluminum base of the vented Opti does indeed run to a vacuum source and, hence is a true vacuum line. 
The other line running to the Optispark cap is a vent line which supplies filtered fresh air to the cap side of the Opti.
If you want to ..... yes, technically, you can unplug and block off the one (1) true vacuum line on BOTH its Optispark and vacuum source ends, but ...... if you block off the vent line without also disconecting the vacuum line source ........ having the vacuum line still "pulling a vacuum" on the Opti WITHOUT a "vent source" ........ will cause the phenolic Optispark distributor cap to deform under normal atmospheric pressure, and cause the cap to hit the rotor underneath it.
Like everyone else asked, WHY would you even be thinking of doing this???
The other line running to the Optispark cap is a vent line which supplies filtered fresh air to the cap side of the Opti. If you want to ..... yes, technically, you can unplug and block off the one (1) true vacuum line on BOTH its Optispark and vacuum source ends, but ...... if you block off the vent line without also disconecting the vacuum line source ........ having the vacuum line still "pulling a vacuum" on the Opti WITHOUT a "vent source" ........ will cause the phenolic Optispark distributor cap to deform under normal atmospheric pressure, and cause the cap to hit the rotor underneath it.
Like everyone else asked, WHY would you even be thinking of doing this???
Last edited by 97 6SPEED Z; Feb 17, 2008 at 09:20 PM.
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Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
First off, (and as others have hinted at above), there are NOT two(2) vacuum lines on a vented Opti. The line from the die cast aluminum base of the vented Opti does indeed run to a vacuum source and, hence is a true vacuum line. The other line running to the Optispark cap is a vent line which supplies filtered fresh air to the cap side of the Opti.
...
The other line running to the Optispark cap is a vent line which supplies filtered fresh air to the cap side of the Opti. ...
Registered User
Joined: Jun 2000
Posts: 857
From: Washington, Michigan USA
I do not have my car handy to check it, and I absolutely believe that Shoebox is probably correct about the cap hose being the vacuum line and the base hose being the fresh air vent, but .............. the important thing we're trying to warn you about is NOT to block the fresh air feed while still "pulling a vacuum" on the Optispark!!! Doing this will cause the Optispark distributor cap to deform over time until it impinges upon the turning rotor beneath it. 
Got it?
Doing this will cause the Optispark distributor cap to deform over time until it impinges upon the turning rotor beneath it. Got it?
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