OptiSpark - Adding Vent Lines with Vented Cap
Anyone else done this?
Yes, I know this is a dead horse that I'm beating.

Does this still hold true as best case - http://www.superchevy.com/how-to/16758/
Last edited by Jazz-LT1; Nov 10, 2014 at 10:10 AM.
I bought an Cardone unit years ago and they replaced it under warranty. The base unit is brand new (rebuilt). The cap is a separately purchased vented unit.

So, a vented early opti on a budget... One change I may make however is to add an inline filter on the supply side to be sure that no dirt gets into the unit. A little added insurance??.
Last edited by Jazz-LT1; Nov 10, 2014 at 11:16 AM.
Early version Opti converted to a vented unit. New harness heat shrink connection. Silicon in the two remaining weep holes. The nipple shown pointing to 6 o'clock position is for the high vacuum side and the other from the cap to the low vacuum side. Also loctite was applied to the rotor screws.
Variation from the factory vented opti is that the fresh air inlet is located on the bottom of the unit rather than the top. I'm also considering adding a filter to the fresh air inlet side to further prevent any debris from entering the system and not plumbing this into the air inlet system. I will be adding a fitting ahead of the MAF sensor. This will prevent any change in the airflow at idle but hopefully produces enough vacuum to be effective.
This is my best attempt at an opti that will live for a while...
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I selected the location for the top fitting to emulate the location on the isolator that MSD uses for its cap in the 8481 kit. It doesn't interfere with the location of the water pump coupler or the opti harness. I switched to a single straight vacuum fitting on the cap (bottom). Less complicated than my original. I got the first vacuum harness from a Cadillac Fleetwood in the local boneyard for $2.00. I bought a new one for a pretty low price of $30.00for the car in my sig. For both, I trimmed the vacuum harness a little bit to get a better fit, since the top port on the isolator is a different location (shorter distance) from the location on factory vented setups from 95-on.
EDIT: I ditched the MSD vacuum harness because it split & rotted after only 2 years.





