Originally Posted by 96capricemgr

I understand that.
I am saying that MSD engineered a vent into the cap and rotor kit for the "unvented" opti.

Originally Posted by litch2004

Well there are two different adjustment screws on the MSD Pro Billet Distributor. There is one set screw that will move the optical sensor further away/further on the shutter wheel. The other set screw moves the optical sensor up and down on the shutter wheel. Like you said though it is just more of a source of trouble. but if it is adjusted here i would think the computer would readjust for changes made.

Now as far as the cap making it a vented system it only is one part of the vented system. you will still not have the vacuum line coming out of the actual distributor. There is also a vented line coming out of the distributor that is located directly above the optical sensor. this vacuum line is connected to the intake tubing. The one that is connected to the cap goes to the vacuum line that the EGR vacuum line is connected to.
The purpose of this is, when a vacuum is pulled from the vacuum line connected to the intake manifold fresh air is then pulled through the distributor via the vacuum line connected to the distributor then the fresh (after air filter) air from the intake/CAI.

Sorry to ramble on like this. Hope this helps out OP. the actual only true benefits to buying this product is the full vented opti for the 93&94 and a hardwired harness. The other benifit is only like 96capricemgr stated; if you are experinced with adjusting the timing using this type of adjustment and a way to prevent the ECM from counter acting the changes you had just made.

Originally Posted by 96capricemgr

I understand that.
I am saying that MSD engineered a vent into the cap and rotor kit for the "unvented" opti.

Originally Posted by WS Sick

But it is not like the factory vacuume vented system, its just a vent to poutside air in the cap alone. If I misunderstood you it appeared to me that you were saying that the MSD cap provided the factory like venting system.

If I misunderstood you I appologize

Originally Posted by WS Sick

Ozone or whatever, the factory system draws fresh air through the whole opti with vacuume, the msd cap alone on a 94 earlier system has no positive pressure pulling ozone and moisture out.

Originally Posted by ss.slp.ls1

Well when the time comes for a cam swap, might as well get a new vented opti a '95 timing cover, and get a cam with the longer dowel pin...problem solved.

Originally Posted by za355tx

I picked up my MSD opti for $250 so I thought I'd give it a shot. It's brand new. I've heard there's some issues for some people and other's say they love them. But like I said I got mine for less than the stock opti sells for so I thought I'd give it a try.

Originally Posted by 94Aquaformula

"WS Sick" Are you saying the msd opti doesnt pull fresh air through vacuum? Like the Factory opti? Its exactly the same. It does pull fresh air through the opti like the factory one.