Hey folks, every link I've googled for this has been dead... Soon to be replacing my opti (again), and the new part came with the vented cap... could someone link me to the parts and instructions on how to hook up a vent line to the new cap?

Thanks!

 

Factory hookup, from Shoebox:

http://shbox.com/1/opti_vacuum_harness.jpg

The factory Opti (95-97) has one vent connector on the body (line from intake elbow), and one on the cap (line to intake manifold vacuum). I'm assuming your new cap has two connections on the cap.


Line from the Opti to the intake manifold:

http://shbox.com/1/opti_vacuum_hose.jpg

Tee that into the EGR vacuum line nipple on the manifold.

http://shbox.com/1/opti_vacuum_conn.jpg


The line that runs from the blue elbow pushed into the intake elBow to the connection on the Opti is a plain hose, no fittings, filter, etc.

 

Thanks injuneer!

There's no inlet on the opti, it's just the regular spline drive one with a vented cap. I'll use those pics you provided to tee a hose (and check valve?) onto the egr line.

I thought I remembered a writeup that tapped the three holes in the bottom for fresh air, but I can't find it now. Might just hook up the vent line and hope that helps a bit at least.

Cheers!

 

The vent is the one that goes to the intake elbow. The vacuum side goes to the intake vacuum port. You don't want to put the vacuum side on without having the vent to the elbow or you will suck the cap in and destroy the cap and rotor. Yes, there was a guide before using the vent holes in the bottom of the opti (don't know where it can be found, now). My recommendation is to get an MSD cap and rotor kit that has provisions for both lines incorporated in it (and includes the hoses). https://documents.holley.com/8481.pdf

 

Now, hopefully, you understand why I said “I'm assuming your new cap has two connections”..... as Rob notes, it won’t work with only one connection. The “vent” only works because clean, filtered air that has passed through the MAF sensor flows into one connection, pulled through the Opti by vacuum from the other connection. The air flow sweeps the ozone, generated by the high voltage discharge in the cap, out of the Opti. The ozone causes rust.

If you apply only the vacuum, with no fresh air inlet, it won’t effectively remove the ozone, can create enough suction to deform the cap and hit the rotor, and can suck engine oil in through the seal on the drive mechanism.

 

Hi,

Here is the how to guide I followed a year and a half ago to vent my ‘94. Hope it helps. It shows how to vent an unvented cap. The one thing I did was used a tiny drill bit and worked up in bit size progressively to create the vent intake vacuum holes/connection that leads to the intake past the MAF sensor. It says that drilling the cap will probably crack it but if you start with a tiny bit and work your way up it will lessen the chances of cracking the cap
Opti-Spark Options

I’m sure this is posted elsewhere on the forum before now but i happened to come across it out there while searching for alternatives.